X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/201f5254b5bbba620893cd607ea182bc25c123d2..dc8091e7b9eb80b77699ac59de3f39eedef65c04:/doc/doc-docbook/spec.xfpt?ds=sidebyside diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 9c2bf199f..fdb318b89 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -41,16 +41,19 @@ .book . ///////////////////////////////////////////////////////////////////////////// -. These definitions set some parameters and save some typing. Remember that -. the element must also be updated for each new edition. +. These definitions set some parameters and save some typing. +. Update the Copyright year (only) when changing content. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.75" -.set version "4.80" +.set previousversion "4.86" +.include ./local_params .set ACL "access control lists (ACLs)" .set I "    " +.macro copyyear +2015 +.endmacro . ///////////////////////////////////////////////////////////////////////////// . Additional xfpt markup used by this document, over and above the default @@ -170,15 +173,18 @@ Specification of the Exim Mail Transfer Agent The Exim MTA -17 May 2012 + +.fulldate + EximMaintainers EM - 4.80 - 17 May 2012 +.versiondatexml EM -2012University of Cambridge + +.copyyear + University of Cambridge .literal off @@ -367,7 +373,7 @@ contributors. .new .cindex "documentation" -This edition of the Exim specification applies to version &version; of Exim. +This edition of the Exim specification applies to version &version() of Exim. Substantive changes from the &previousversion; edition are marked in some renditions of the document; this paragraph is so marked if the rendition is capable of showing a change indicator. @@ -533,10 +539,25 @@ The &_.bz2_& file is usually a lot smaller than the &_.gz_& file. .cindex "distribution" "signing details" .cindex "distribution" "public key" .cindex "public key for signed distribution" -The distributions are currently signed with Nigel Metheringham's GPG key. The -corresponding public key is available from a number of keyservers, and there is -also a copy in the file &_nigel-pubkey.asc_&. The signatures for the tar bundles are -in: +The distributions will be PGP signed by an individual key of the Release +Coordinator. This key will have a uid containing an email address in the +&'exim.org'& domain and will have signatures from other people, including +other Exim maintainers. We expect that the key will be in the "strong set" of +PGP keys. There should be a trust path to that key from Nigel Metheringham's +PGP key, a version of which can be found in the release directory in the file +&_nigel-pubkey.asc_&. All keys used will be available in public keyserver pools, +such as &'pool.sks-keyservers.net'&. + +At time of last update, releases were being made by Phil Pennock and signed with +key &'0x403043153903637F'&, although that key is expected to be replaced in 2013. +A trust path from Nigel's key to Phil's can be observed at +&url(https://www.security.spodhuis.org/exim-trustpath). + +Releases have also been authorized to be performed by Todd Lyons who signs with +key &'0xC4F4F94804D29EBA'&. A direct trust path exists between previous RE Phil +Pennock and Todd Lyons through a common associate. + +The signatures for the tar bundles are in: .display &_exim-n.nn.tar.gz.asc_& &_exim-n.nn.tar.bz2.asc_& @@ -722,6 +743,7 @@ the Exim documentation, &"spool"& is always used in the first sense. .cindex "incorporated code" .cindex "regular expressions" "library" .cindex "PCRE" +.cindex "OpenDMARC" A number of pieces of external code are included in the Exim distribution. .ilist @@ -846,6 +868,14 @@ ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .endblockquote +.next +.cindex "opendmarc" "acknowledgment" +The DMARC implementation uses the OpenDMARC library which is Copyrighted by +The Trusted Domain Project. Portions of Exim source which use OpenDMARC +derived code are indicated in the respective source files. The full OpenDMARC +license is provided in the LICENSE.opendmarc file contained in the distributed +source code. + .next Many people have contributed code fragments, some large, some small, that were not covered by any specific licence requirements. It is assumed that the @@ -1348,6 +1378,7 @@ Setting the &%verify%& option actually sets two options, &%verify_sender%& and &%verify_recipient%&, which independently control the use of the router for sender and recipient verification. You can set these options directly if you want a router to be used for only one type of verification. +Note that cutthrough delivery is classed as a recipient verification for this purpose. .next If the &%address_test%& option is set false, the router is skipped when Exim is run with the &%-bt%& option to test an address routing. This can be helpful @@ -1357,6 +1388,7 @@ having to simulate the effect of the scanner. .next Routers can be designated for use only when verifying an address, as opposed to routing it for delivery. The &%verify_only%& option controls this. +Again, cutthrough delivery counts as a verification. .next Individual routers can be explicitly skipped when running the routers to check an address given in the SMTP EXPN command (see the &%expn%& option). @@ -1543,7 +1575,7 @@ If a host is unreachable for a period of time, a number of messages may be waiting for it by the time it recovers, and sending them in a single SMTP connection is clearly beneficial. Whenever a delivery to a remote host is deferred, -.cindex "hints database" +.cindex "hints database" "deferred deliveries" Exim makes a note in its hints database, and whenever a successful SMTP delivery has happened, it looks to see if any other messages are waiting for the same host. If any are found, they are sent over the same SMTP @@ -1602,7 +1634,7 @@ for only a short time (see &%timeout_frozen_after%& and .section "Unpacking" "SECID23" Exim is distributed as a gzipped or bzipped tar file which, when unpacked, creates a directory with the name of the current release (for example, -&_exim-&version;_&) into which the following files are placed: +&_exim-&version()_&) into which the following files are placed: .table2 140pt .irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments" @@ -1647,7 +1679,6 @@ architecture and operating system for itself, but the defaults can be overridden if necessary. -.new .section "PCRE library" "SECTpcre" .cindex "PCRE library" Exim no longer has an embedded PCRE library as the vast majority of @@ -1662,7 +1693,6 @@ If your operating system has no PCRE support then you will need to obtain and build the current PCRE from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/). More information on PCRE is available at &url(http://www.pcre.org/). -.wen .section "DBM libraries" "SECTdb" .cindex "DBM libraries" "discussion of" @@ -1830,7 +1860,7 @@ described RFC 2047. This makes it possible to transmit characters that are not in the ASCII character set, and to label them as being in a particular character set. When Exim is inspecting header lines by means of the &%$h_%& mechanism, it decodes them, and translates them into a specified character set -(default ISO-8859-1). The translation is possible only if the operating system +(default is set at build time). The translation is possible only if the operating system supports the &[iconv()]& function. However, some of the operating systems that supply &[iconv()]& do not support @@ -1873,14 +1903,12 @@ SUPPORT_TLS=yes TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto TLS_INCLUDE=-I/usr/local/openssl/include/ .endd -.new .cindex "pkg-config" "OpenSSL" If you have &'pkg-config'& available, then instead you can just use: .code SUPPORT_TLS=yes USE_OPENSSL_PC=openssl .endd -.wen .cindex "USE_GNUTLS" If GnuTLS is installed, you should set .code @@ -1896,7 +1924,6 @@ USE_GNUTLS=yes TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt TLS_INCLUDE=-I/usr/gnu/include .endd -.new .cindex "pkg-config" "GnuTLS" If you have &'pkg-config'& available, then instead you can just use: .code @@ -1904,7 +1931,6 @@ SUPPORT_TLS=yes USE_GNUTLS=yes USE_GNUTLS_PC=gnutls .endd -.wen You do not need to set TLS_INCLUDE if the relevant directory is already specified in INCLUDE. Details of how to configure Exim to make use of TLS are @@ -1942,7 +1968,7 @@ in your &_/etc/hosts.allow_& file allows connections from the local host, from the subnet 192.168.1.0/24, and from all hosts in &'friendly.domain.example'&. All other connections are denied. The daemon name used by &'tcpwrappers'& can be changed at build time by setting TCP_WRAPPERS_DAEMON_NAME in -in &_Local/Makefile_&, or by setting tcp_wrappers_daemon_name in the +&_Local/Makefile_&, or by setting tcp_wrappers_daemon_name in the configure file. Consult the &'tcpwrappers'& documentation for further details. @@ -1959,10 +1985,10 @@ Two different types of DNS record for handling IPv6 addresses have been defined. AAAA records (analogous to A records for IPv4) are in use, and are currently seen as the mainstream. Another record type called A6 was proposed as better than AAAA because it had more flexibility. However, it was felt to be -over-complex, and its status was reduced to &"experimental"&. It is not known -if anyone is actually using A6 records. Exim has support for A6 records, but -this is included only if you set &`SUPPORT_A6=YES`& in &_Local/Makefile_&. The -support has not been tested for some time. +over-complex, and its status was reduced to &"experimental"&. +Exim used to +have a compile option for including A6 record support but this has now been +withdrawn. @@ -2006,9 +2032,6 @@ For example, on a Sun system running Solaris 8, the directory .cindex "symbolic link" "to source files" Symbolic links to relevant source files are installed in the build directory. -&*Warning*&: The &%-j%& (parallel) flag must not be used with &'make'&; the -building process fails if it is set. - If this is the first time &'make'& has been run, it calls a script that builds a make file inside the build directory, using the configuration files from the &_Local_& directory. The new make file is then passed to another instance of @@ -2133,7 +2156,6 @@ files or libraries are required. When a lookup type is not included in the binary, attempts to configure Exim to use it cause run time configuration errors. -.new .cindex "pkg-config" "lookups" .cindex "pkg-config" "authenticators" Many systems now use a tool called &'pkg-config'& to encapsulate information @@ -2153,7 +2175,6 @@ AUTH_GSASL_PC=libgsasl AUTH_HEIMDAL_GSSAPI=yes AUTH_HEIMDAL_GSSAPI_PC=heimdal-gssapi .endd -.wen .cindex "Perl" "including support for" Exim can be linked with an embedded Perl interpreter, allowing Perl @@ -2306,7 +2327,7 @@ INFO_DIRECTORY, as described in section &<>& below. For the utility programs, old versions are renamed by adding the suffix &_.O_& to their names. The Exim binary itself, however, is handled differently. It is installed under a name that includes the version number and the compile number, -for example &_exim-&version;-1_&. The script then arranges for a symbolic link +for example &_exim-&version()-1_&. The script then arranges for a symbolic link called &_exim_& to point to the binary. If you are updating a previous version of Exim, the script takes care to ensure that the name &_exim_& is never absent from the directory (as seen by other processes). @@ -2686,6 +2707,13 @@ no arguments. This option is an alias for &%-bV%& and causes version information to be displayed. +.vitem &%-Ac%& &&& + &%-Am%& +.oindex "&%-Ac%&" +.oindex "&%-Am%&" +These options are used by Sendmail for selecting configuration files and are +ignored by Exim. + .vitem &%-B%&<&'type'&> .oindex "&%-B%&" .cindex "8-bit characters" @@ -2945,11 +2973,37 @@ use the &'exim_dbmbuild'& utility, or some other means, to rebuild alias files if this is required. If the &%bi_command%& option is not set, calling Exim with &%-bi%& is a no-op. +. // Keep :help first, then the rest in alphabetical order +.vitem &%-bI:help%& +.oindex "&%-bI:help%&" +.cindex "querying exim information" +We shall provide various options starting &`-bI:`& for querying Exim for +information. The output of many of these will be intended for machine +consumption. This one is not. The &%-bI:help%& option asks Exim for a +synopsis of supported options beginning &`-bI:`&. Use of any of these +options shall cause Exim to exit after producing the requested output. + +.vitem &%-bI:dscp%& +.oindex "&%-bI:dscp%&" +.cindex "DSCP" "values" +This option causes Exim to emit an alphabetically sorted list of all +recognised DSCP names. + +.vitem &%-bI:sieve%& +.oindex "&%-bI:sieve%&" +.cindex "Sieve filter" "capabilities" +This option causes Exim to emit an alphabetically sorted list of all supported +Sieve protocol extensions on stdout, one per line. This is anticipated to be +useful for ManageSieve (RFC 5804) implementations, in providing that protocol's +&`SIEVE`& capability response line. As the precise list may depend upon +compile-time build options, which this option will adapt to, this is the only +way to guarantee a correct response. + .vitem &%-bm%& .oindex "&%-bm%&" .cindex "local message reception" This option runs an Exim receiving process that accepts an incoming, -locally-generated message on the current input. The recipients are given as the +locally-generated message on the standard input. The recipients are given as the command arguments (except when &%-t%& is also present &-- see below). Each argument can be a comma-separated list of RFC 2822 addresses. This is the default option for selecting the overall action of an Exim call; it is assumed @@ -3053,11 +3107,19 @@ users, the output is as in this example: .code mysql_servers = .endd -If &%configure_file%& is given as an argument, the name of the run time -configuration file is output. +If &%config%& is given as an argument, the config is +output, as it was parsed, any include file resolved, any comment removed. + +If &%config_file%& is given as an argument, the name of the run time +configuration file is output. (&%configure_file%& works too, for +backward compatibility.) If a list of configuration files was supplied, the value that is output here is the name of the file that was actually used. +.cindex "options" "hiding name of" +If the &%-n%& flag is given, then for most modes of &%-bP%& operation the +name will not be output. + .cindex "daemon" "process id (pid)" .cindex "pid (process id)" "of daemon" If &%log_file_path%& or &%pid_file_path%& are given, the names of the @@ -3089,6 +3151,11 @@ using one of the words &%router_list%&, &%transport_list%&, or settings can be obtained by using &%routers%&, &%transports%&, or &%authenticators%&. +.cindex "environment" +If &%environment%& is given as an argument, the set of environment +variables is output, line by line. Using the &%-n%& flag suppresses the value of the +variables. + .cindex "options" "macro &-- extracting" If invoked by an admin user, then &%macro%&, &%macro_list%& and &%macros%& are available, similarly to the drivers. Because macros are sometimes used @@ -3490,6 +3557,9 @@ example: exim '-D ABC = something' ... .endd &%-D%& may be repeated up to 10 times on a command line. +.new +Only macro names up to 22 letters long can be set. +.wen .vitem &%-d%&<&'debug&~options'&> @@ -3660,8 +3730,17 @@ if &%-f%& is also present, it overrides &"From&~"&. .vitem &%-G%& .oindex "&%-G%&" -.cindex "Sendmail compatibility" "&%-G%& option ignored" -This is a Sendmail option which is ignored by Exim. +.cindex "submission fixups, suppressing (command-line)" +This option is equivalent to an ACL applying: +.code +control = suppress_local_fixups +.endd +for every message received. Note that Sendmail will complain about such +bad formatting, where Exim silently just does not fix it up. This may change +in future. + +As this affects audit information, the caller must be a trusted user to use +this option. .vitem &%-h%&&~<&'number'&> .oindex "&%-h%&" @@ -3679,6 +3758,17 @@ line by itself should not terminate an incoming, non-SMTP message. I can find no documentation for this option in Solaris 2.4 Sendmail, but the &'mailx'& command in Solaris 2.4 uses it. See also &%-ti%&. +.vitem &%-L%&&~<&'tag'&> +.oindex "&%-L%&" +.cindex "syslog" "process name; set with flag" +This option is equivalent to setting &%syslog_processname%& in the config +file and setting &%log_file_path%& to &`syslog`&. +Its use is restricted to administrators. The configuration file has to be +read and parsed, to determine access rights, before this is set and takes +effect, so early configuration file errors will not honour this flag. + +The tag should not be longer than 32 characters. + .vitem &%-M%&&~<&'message&~id'&>&~<&'message&~id'&>&~... .oindex "&%-M%&" .cindex "forcing delivery" @@ -3730,6 +3820,12 @@ This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the connection to the remote host has been authenticated. +.vitem &%-MCD%& +.oindex "&%-MCD%&" +This option is not intended for use by external callers. It is used internally +by Exim in conjunction with the &%-MC%& option. It signifies that the +remote host supports the ESMTP &_DSN_& extension. + .vitem &%-MCP%& .oindex "&%-MCP%&" This option is not intended for use by external callers. It is used internally @@ -3919,9 +4015,9 @@ for that message. .vitem &%-n%& .oindex "&%-n%&" -.cindex "Sendmail compatibility" "&%-n%& option ignored" -This option is interpreted by Sendmail to mean &"no aliasing"&. It is ignored -by Exim. +This option is interpreted by Sendmail to mean &"no aliasing"&. +For normal modes of operation, it is ignored by Exim. +When combined with &%-bP%& it suppresses the name of an option from being output. .vitem &%-O%&&~<&'data'&> .oindex "&%-O%&" @@ -4035,8 +4131,8 @@ message. Provided this error message is successfully sent, the Exim receiving process exits with a return code of zero. If not, the return code is 2 if the problem -is that the original message has no recipients, or 1 any other error. This is -the default &%-oe%&&'x'& option if Exim is called as &'rmail'&. +is that the original message has no recipients, or 1 for any other error. +This is the default &%-oe%&&'x'& option if Exim is called as &'rmail'&. .vitem &%-oem%& .oindex "&%-oem%&" @@ -4140,6 +4236,20 @@ option sets the IP interface address value. A port number may be included, using the same syntax as for &%-oMa%&. The interface address is placed in &$received_ip_address$& and the port number, if present, in &$received_port$&. +.vitem &%-oMm%&&~<&'message&~reference'&> +.oindex "&%-oMm%&" +.cindex "message reference" "message reference, specifying for local message" +See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMm%& +option sets the message reference, e.g. message-id, and is logged during +delivery. This is useful when some kind of audit trail is required to tie +messages together. The format of the message reference is checked and will +abort if the format is invalid. The option will only be accepted if exim is +running in trusted mode, not as any regular user. + +The best example of a message reference is when Exim sends a bounce message. +The message reference is the message-id of the original message for which Exim +is sending the bounce. + .vitem &%-oMr%&&~<&'protocol&~name'&> .oindex "&%-oMr%&" .cindex "protocol, specifying for local message" @@ -4249,7 +4359,7 @@ For compatibility with Sendmail, this option is equivalent to It sets the incoming protocol and host name (for trusted callers). The host name and its colon can be omitted when only the protocol is to be set. Note the Exim already has two private options, &%-pd%& and &%-ps%&, that refer -to embedded Perl. It is therefore impossible to set a protocol value of &`p`& +to embedded Perl. It is therefore impossible to set a protocol value of &`d`& or &`s`& using this option (but that does not seem a real limitation). .vitem &%-q%& @@ -4456,7 +4566,7 @@ has &'f'& or &'ff'& in its flags, the associated action is taken. .vitem &%-Tqt%&&~<&'times'&> .oindex "&%-Tqt%&" -This an option that is exclusively for use by the Exim testing suite. It is not +This is an option that is exclusively for use by the Exim testing suite. It is not recognized when Exim is run normally. It allows for the setting up of explicit &"queue times"& so that various warning/retry features can be tested. @@ -4540,6 +4650,18 @@ AIX uses &%-x%& for a private purpose (&"mail from a local mail program has National Language Support extended characters in the body of the mail item"&). It sets &%-x%& when calling the MTA from its &%mail%& command. Exim ignores this option. + +.vitem &%-X%&&~<&'logfile'&> +.oindex "&%-X%&" +This option is interpreted by Sendmail to cause debug information to be sent +to the named file. It is ignored by Exim. + +.vitem &%-z%&&~<&'log-line'&> +.oindex "&%-z%&" +This option writes its argument to Exim's logfile. +Use is restricted to administrators; the intent is for operational notes. +Quotes should be used to maintain a multi-word item as a single argument, +under most shells. .endlist .ecindex IIDclo1 @@ -4690,8 +4812,8 @@ help with this. See the comments in &_src/EDITME_& for details. Exim's configuration file is divided into a number of different parts. General option settings must always appear at the start of the file. The other parts are all optional, and may appear in any order. Each part other than the first -is introduced by the word &"begin"& followed by the name of the part. The -optional parts are: +is introduced by the word &"begin"& followed by at least one literal +space, and the name of the part. The optional parts are: .ilist &'ACL'&: Access control lists for controlling incoming SMTP mail (see chapter @@ -4896,7 +5018,8 @@ message_size_limit = 50M message_size_limit = 100M .endif .endd -sets a message size limit of 50M if the macro &`AAA`& is defined, and 100M +sets a message size limit of 50M if the macro &`AAA`& is defined +(or &`A`& or &`AA`&), and 100M otherwise. If there is more than one macro named on the line, the condition is true if any of them are defined. That is, it is an &"or"& condition. To obtain an &"and"& condition, you need to use nested &`.ifdef`&s. @@ -5118,7 +5241,7 @@ list items, it is not ignored when parsing the list. The space after the first colon in the example above is necessary. If it were not there, the list would be interpreted as the two items 127.0.0.1:: and 1. -.section "Changing list separators" "SECID53" +.section "Changing list separators" "SECTlistsepchange" .cindex "list separator" "changing" .cindex "IPv6" "addresses in lists" Doubling colons in IPv6 addresses is an unwelcome chore, so a mechanism was @@ -5303,7 +5426,7 @@ it is unset, Exim uses the &[uname()]& system function to obtain the host name. The first three non-comment configuration lines are as follows: .code -domainlist local_domains = @ +domainlist local_domains = @ domainlist relay_to_domains = hostlist relay_from_hosts = 127.0.0.1 .endd @@ -5458,15 +5581,20 @@ The next two lines are concerned with &'ident'& callbacks, as defined by RFC 1413 (hence their names): .code rfc1413_hosts = * -rfc1413_query_timeout = 5s +rfc1413_query_timeout = 0s +.endd +These settings cause Exim to avoid ident callbacks for all incoming SMTP calls. +Few hosts offer RFC1413 service these days; calls have to be +terminated by a timeout and this needlessly delays the startup +of an incoming SMTP connection. +If you have hosts for which you trust RFC1413 and need this +information, you can change this. + +This line enables an efficiency SMTP option. It is negotiated by clients +and not expected to cause problems but can be disabled if needed. +.code +prdr_enable = true .endd -These settings cause Exim to make ident callbacks for all incoming SMTP calls. -You can limit the hosts to which these calls are made, or change the timeout -that is used. If you set the timeout to zero, all ident calls are disabled. -Although they are cheap and can provide useful information for tracing problem -messages, some hosts and firewalls have problems with ident calls. This can -result in a timeout instead of an immediate refused connection, leading to -delays on starting up an incoming SMTP session. When Exim receives messages over SMTP connections, it expects all addresses to be fully qualified with a domain, as required by the SMTP definition. However, @@ -5479,6 +5607,13 @@ find that they send unqualified addresses. The two commented-out options: show how you can specify hosts that are permitted to send unqualified sender and recipient addresses, respectively. +The &%log_selector%& option is used to increase the detail of logging +over the default: +.code +log_selector = +smtp_protocol_error +smtp_syntax_error \ + +tls_certificate_verified +.endd + The &%percent_hack_domains%& option is also commented out: .code # percent_hack_domains = @@ -5645,7 +5780,7 @@ examples described in &<>&. This means that no client can in fact authenticate until you complete the authenticator definitions. .code require message = relay not permitted - domains = +local_domains : +relay_domains + domains = +local_domains : +relay_to_domains .endd This statement rejects the address if its domain is neither a local domain nor one of the domains for which this host is a relay. @@ -5902,9 +6037,14 @@ One remote transport and four local transports are defined. .code remote_smtp: driver = smtp + hosts_try_prdr = * .endd -This transport is used for delivering messages over SMTP connections. All its -options are defaulted. The list of remote hosts comes from the router. +This transport is used for delivering messages over SMTP connections. +The list of remote hosts comes from the router. +The &%hosts_try_prdr%& option enables an efficiency SMTP option. +It is negotiated between client and server +and not expected to cause problems but can be disabled if needed. +All other options are defaulted. .code local_delivery: driver = appendfile @@ -5932,8 +6072,8 @@ address_pipe: .endd This transport is used for handling deliveries to pipes that are generated by redirection (aliasing or users' &_.forward_& files). The &%return_output%& -option specifies that any output generated by the pipe is to be returned to the -sender. +option specifies that any output on stdout or stderr generated by the pipe is to +be returned to the sender. .code address_file: driver = appendfile @@ -6007,7 +6147,7 @@ The example PLAIN authenticator looks like this: # server_set_id = $auth2 # server_prompts = : # server_condition = Authentication is not yet configured -# server_advertise_condition = ${if def:tls_cipher } +# server_advertise_condition = ${if def:tls_in_cipher } .endd And the example LOGIN authenticator looks like this: .code @@ -6016,7 +6156,7 @@ And the example LOGIN authenticator looks like this: # server_set_id = $auth1 # server_prompts = <| Username: | Password: # server_condition = Authentication is not yet configured -# server_advertise_condition = ${if def:tls_cipher } +# server_advertise_condition = ${if def:tls_in_cipher } .endd The &%server_set_id%& option makes Exim remember the authenticated username @@ -6115,12 +6255,14 @@ cause parts of the string to be replaced by data that is obtained from the lookup. Lookups of this type are conditional expansion items. Different results can be defined for the cases of lookup success and failure. See chapter &<>&, where string expansions are described in detail. +The key for the lookup is specified as part of the string expansion. .next Lists of domains, hosts, and email addresses can contain lookup requests as a way of avoiding excessively long linear lists. In this case, the data that is returned by the lookup is often (but not always) discarded; whether the lookup succeeds or fails is what really counts. These kinds of list are described in chapter &<>&. +The key for the lookup is given by the context in which the list is expanded. .endlist String expansions, lists, and lookups interact with each other in such a way @@ -6245,7 +6387,6 @@ using Berkeley DB versions 3 or 4, it opens existing databases for reading with the DB_UNKNOWN option. This enables it to handle any of the types of database that the library supports, and can be useful for accessing DBM files created by other applications. (For earlier DB versions, DB_HASH is always used.) -.new .next .cindex "lookup" "dbmjz" .cindex "lookup" "dbm &-- embedded NULs" @@ -6257,7 +6398,6 @@ ASCII NUL characters to form the lookup key. An example usage would be to authenticate incoming SMTP calls using the passwords from Cyrus SASL's &_/etc/sasldb2_& file with the &(gsasl)& authenticator or Exim's own &(cram_md5)& authenticator. -.wen .next .cindex "lookup" "dbmnz" .cindex "lookup" "dbm &-- terminating zero" @@ -6489,6 +6629,14 @@ password value. For example: &(pgsql)&: The format of the query is an SQL statement that is passed to a PostgreSQL database. See section &<>&. +.next +.new +.cindex "Redis lookup type" +.cindex lookup Redis +&(redis)&: The format of the query is an SQL statement that is passed to a +Redis database. See section &<>&. +.wen + .next .cindex "sqlite lookup type" .cindex "lookup" "sqlite" @@ -6756,13 +6904,28 @@ is used on its own as the result. If the lookup does not succeed, the &`fail`& keyword causes a &'forced expansion failure'& &-- see section &<>& for an explanation of what this means. -.new -The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, and TXT, -and, when Exim is compiled with IPv6 support, AAAA (and A6 if that is also -configured). If no type is given, TXT is assumed. When the type is PTR, +The supported DNS record types are A, CNAME, MX, NS, PTR, SOA, SPF, SRV, TLSA +and TXT, and, when Exim is compiled with IPv6 support, AAAA. +If no type is given, TXT is assumed. + +For any record type, if multiple records are found, the data is returned as a +concatenation, with newline as the default separator. The order, of course, +depends on the DNS resolver. You can specify a different separator character +between multiple records by putting a right angle-bracket followed immediately +by the new separator at the start of the query. For example: +.code +${lookup dnsdb{>: a=host1.example}} +.endd +It is permitted to specify a space as the separator character. Further +white space is ignored. +For lookup types that return multiple fields per record, +an alternate field separator can be specified using a comma after the main +separator character, followed immediately by the field separator. + +.cindex "PTR record" "in &(dnsdb)& lookup" +When the type is PTR, the data can be an IP address, written as normal; inversion and the addition of &%in-addr.arpa%& or &%ip6.arpa%& happens automatically. For example: -.wen .code ${lookup dnsdb{ptr=192.168.4.5}{$value}fail} .endd @@ -6774,28 +6937,15 @@ altered and nothing is added. For an MX lookup, both the preference value and the host name are returned for each record, separated by a space. For an SRV lookup, the priority, weight, port, and host name are returned for each record, separated by spaces. - -For any record type, if multiple records are found (or, for A6 lookups, if a -single record leads to multiple addresses), the data is returned as a -concatenation, with newline as the default separator. The order, of course, -depends on the DNS resolver. You can specify a different separator character -between multiple records by putting a right angle-bracket followed immediately -by the new separator at the start of the query. For example: -.code -${lookup dnsdb{>: a=host1.example}} -.endd -It is permitted to specify a space as the separator character. Further -white space is ignored. +The field separator can be modified as above. .cindex "TXT record" "in &(dnsdb)& lookup" .cindex "SPF record" "in &(dnsdb)& lookup" -.new For TXT records with multiple items of data, only the first item is returned, -unless a separator for them is specified using a comma after the separator -character followed immediately by the TXT record item separator. To concatenate -items without a separator, use a semicolon instead. For SPF records the +unless a field separator is specified. +To concatenate items without a separator, use a semicolon instead. +For SPF records the default behaviour is to concatenate multiple items without using a separator. -.wen .code ${lookup dnsdb{>\n,: txt=a.b.example}} ${lookup dnsdb{>\n; txt=a.b.example}} @@ -6804,6 +6954,75 @@ ${lookup dnsdb{spf=example.org}} It is permitted to specify a space as the separator character. Further white space is ignored. +.cindex "SOA record" "in &(dnsdb)& lookup" +For an SOA lookup, while no result is obtained the lookup is redone with +successively more leading components dropped from the given domain. +Only the primary-nameserver field is returned unless a field separator is +specified. +.code +${lookup dnsdb{>:,; soa=a.b.example.com}} +.endd + +.section "Dnsdb lookup modifiers" "SECTdnsdb_mod" +.cindex "dnsdb modifiers" +.cindex "modifiers" "dnsdb" +.cindex "options" "dnsdb" +Modifiers for &(dnsdb)& lookups are given by optional keywords, +each followed by a comma, +that may appear before the record type. + +The &(dnsdb)& lookup fails only if all the DNS lookups fail. If there is a +temporary DNS error for any of them, the behaviour is controlled by +a defer-option modifier. +The possible keywords are +&"defer_strict"&, &"defer_never"&, and &"defer_lax"&. +With &"strict"& behaviour, any temporary DNS error causes the +whole lookup to defer. With &"never"& behaviour, a temporary DNS error is +ignored, and the behaviour is as if the DNS lookup failed to find anything. +With &"lax"& behaviour, all the queries are attempted, but a temporary DNS +error causes the whole lookup to defer only if none of the other lookups +succeed. The default is &"lax"&, so the following lookups are equivalent: +.code +${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}} +${lookup dnsdb{a=one.host.com:two.host.com}} +.endd +Thus, in the default case, as long as at least one of the DNS lookups +yields some data, the lookup succeeds. + +.cindex "DNSSEC" "dns lookup" +Use of &(DNSSEC)& is controlled by a dnssec modifier. +The possible keywords are +&"dnssec_strict"&, &"dnssec_lax"&, and &"dnssec_never"&. +With &"strict"& or &"lax"& DNSSEC information is requested +with the lookup. +With &"strict"& a response from the DNS resolver that +is not labelled as authenticated data +is treated as equivalent to a temporary DNS error. +The default is &"never"&. + +See also the &$lookup_dnssec_authenticated$& variable. + +.cindex timeout "dns lookup" +.cindex "DNS" timeout +Timeout for the dnsdb lookup can be controlled by a retrans modifier. +The form is &"retrans_VAL"& where VAL is an Exim time specification +(e.g. &"5s"&). +The default value is set by the main configuration option &%dns_retrans%&. + +Retries for the dnsdb lookup can be controlled by a retry modifier. +The form if &"retry_VAL"& where VAL is an integer. +The default count is set by the main configuration option &%dns_retry%&. + +.new +.cindex cacheing "of dns lookup" +.cindex TTL "of dns lookup" +.cindex DNS TTL +Dnsdb lookup results are cached within a single process (and its children). +The cache entry lifetime is limited to the smallest time-to-live (TTL) +value of the set of returned DNS records. +.wen + + .section "Pseudo dnsdb record types" "SECID66" .cindex "MX record" "in &(dnsdb)& lookup" By default, both the preference value and the host name are returned for @@ -6851,6 +7070,14 @@ has two space-separated fields: an authorization code and a target host name. The authorization code can be &"Y"& for yes, &"N"& for no, &"X"& for explicit authorization required but absent, or &"?"& for unknown. +.cindex "A+" "in &(dnsdb)& lookup" +The pseudo-type A+ performs an AAAA +and then an A lookup. All results are returned; defer processing +(see below) is handled separately for each lookup. Example: +.code +${lookup dnsdb {>; a+=$sender_helo_name}} +.endd + .section "Multiple dnsdb lookups" "SECID67" In the previous sections, &(dnsdb)& lookups for a single domain are described. @@ -6871,23 +7098,6 @@ The data from each lookup is concatenated, with newline separators by default, in the same way that multiple DNS records for a single item are handled. A different separator can be specified, as described above. -The &(dnsdb)& lookup fails only if all the DNS lookups fail. If there is a -temporary DNS error for any of them, the behaviour is controlled by -an optional keyword followed by a comma that may appear before the record -type. The possible keywords are &"defer_strict"&, &"defer_never"&, and -&"defer_lax"&. With &"strict"& behaviour, any temporary DNS error causes the -whole lookup to defer. With &"never"& behaviour, a temporary DNS error is -ignored, and the behaviour is as if the DNS lookup failed to find anything. -With &"lax"& behaviour, all the queries are attempted, but a temporary DNS -error causes the whole lookup to defer only if none of the other lookups -succeed. The default is &"lax"&, so the following lookups are equivalent: -.code -${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}} -${lookup dnsdb{a=one.host.com:two.host.com}} -.endd -Thus, in the default case, as long as at least one of the DNS lookups -yields some data, the lookup succeeds. - @@ -6952,6 +7162,16 @@ With sufficiently modern LDAP libraries, Exim supports forcing TLS over regular LDAP connections, rather than the SSL-on-connect &`ldaps`&. See the &%ldap_start_tls%& option. +Starting with Exim 4.83, the initialization of LDAP with TLS is more tightly +controlled. Every part of the TLS configuration can be configured by settings in +&_exim.conf_&. Depending on the version of the client libraries installed on +your system, some of the initialization may have required setting options in +&_/etc/ldap.conf_& or &_~/.ldaprc_& to get TLS working with self-signed +certificates. This revealed a nuance where the current UID that exim was +running as could affect which config files it read. With Exim 4.83, these +methods become optional, only taking effect if not specifically set in +&_exim.conf_&. + .section "LDAP quoting" "SECID68" .cindex "LDAP" "quoting" @@ -7098,6 +7318,7 @@ them. The following names are recognized: &`USER `& set the DN, for authenticating the LDAP bind &`PASS `& set the password, likewise &`REFERRALS `& set the referrals parameter +&`SERVERS `& set alternate server list for this query only &`SIZE `& set the limit for the number of entries returned &`TIME `& set the maximum waiting time for a query .endd @@ -7106,6 +7327,8 @@ The value of the DEREFERENCE parameter must be one of the words &"never"&, must be &"follow"& (the default) or &"nofollow"&. The latter stops the LDAP library from trying to follow referrals issued by the LDAP server. +.cindex LDAP timeout +.cindex timeout "LDAP lookup" The name CONNECT is an obsolete name for NETTIME, retained for backwards compatibility. This timeout (specified as a number of seconds) is enforced from the client end for operations that can be carried out over a @@ -7119,6 +7342,13 @@ Netscape SDK; for OpenLDAP no action is taken. The TIME parameter (also a number of seconds) is passed to the server to set a server-side limit on the time taken to complete a search. +The SERVERS parameter allows you to specify an alternate list of ldap servers +to use for an individual lookup. The global &%ldap_default_servers%& option provides a +default list of ldap servers, and a single lookup can specify a single ldap +server to use. But when you need to do a lookup with a list of servers that is +different than the default list (maybe different order, maybe a completely +different set of servers), the SERVERS parameter allows you to specify this +alternate list (colon-separated). Here is an example of an LDAP query in an Exim lookup that uses some of these values. This is a single line, folded to fit on the page: @@ -7173,7 +7403,7 @@ SMTP authentication. See the &%ldapauth%& expansion string condition in chapter The &(ldapdn)& lookup type returns the Distinguished Name from a single entry as a sequence of values, for example .code -cn=manager, o=University of Cambridge, c=UK +cn=manager,o=University of Cambridge,c=UK .endd The &(ldap)& lookup type generates an error if more than one entry matches the search filter, whereas &(ldapm)& permits this case, and inserts a newline in @@ -7184,36 +7414,50 @@ directory. In the common case where you specify a single attribute in your LDAP query, the result is not quoted, and does not contain the attribute name. If the attribute -has multiple values, they are separated by commas. +has multiple values, they are separated by commas. Any comma that is +part of an attribute's value is doubled. If you specify multiple attributes, the result contains space-separated, quoted strings, each preceded by the attribute name and an equals sign. Within the quotes, the quote character, backslash, and newline are escaped with backslashes, and commas are used to separate multiple values for the attribute. +Any commas in attribute values are doubled +(permitting treatment of the values as a comma-separated list). Apart from the escaping, the string within quotes takes the same form as the output when a single attribute is requested. Specifying no attributes is the same as specifying all of an entry's attributes. Here are some examples of the output format. The first line of each pair is an LDAP query, and the second is the data that is returned. The attribute called -&%attr1%& has two values, whereas &%attr2%& has only one value: +&%attr1%& has two values, one of them with an embedded comma, whereas +&%attr2%& has only one value. Both attributes are derived from &%attr%& +(they have SUP &%attr%& in their schema definitions). + .code ldap:///o=base?attr1?sub?(uid=fred) -value1.1, value1.2 +value1.1,value1,,2 ldap:///o=base?attr2?sub?(uid=fred) value two +ldap:///o=base?attr?sub?(uid=fred) +value1.1,value1,,2,value two + ldap:///o=base?attr1,attr2?sub?(uid=fred) -attr1="value1.1, value1.2" attr2="value two" +attr1="value1.1,value1,,2" attr2="value two" ldap:///o=base??sub?(uid=fred) -objectClass="top" attr1="value1.1, value1.2" attr2="value two" +objectClass="top" attr1="value1.1,value1,,2" attr2="value two" .endd -The &%extract%& operator in string expansions can be used to pick out -individual fields from data that consists of &'key'&=&'value'& pairs. You can +You can make use of Exim's &%-be%& option to run expansion tests and thereby check the results of LDAP lookups. +The &%extract%& operator in string expansions can be used to pick out +individual fields from data that consists of &'key'&=&'value'& pairs. +The &%listextract%& operator should be used to pick out individual values +of attributes, even when only a single value is expected. +The doubling of embedded commas allows you to use the returned data as a +comma separated list (using the "<," syntax for changing the input list separator). @@ -7258,7 +7502,10 @@ operator is to double any quote characters within the text. .cindex "lookup" "Oracle" .cindex "InterBase lookup type" .cindex "lookup" "InterBase" -Exim can support lookups in InterBase, MySQL, Oracle, PostgreSQL, and SQLite +.cindex "Redis lookup type" +.cindex lookup Redis +Exim can support lookups in InterBase, MySQL, Oracle, PostgreSQL, Redis, +and SQLite databases. Queries for these databases contain SQL statements, so an example might be .code @@ -7285,7 +7532,7 @@ If the result of the query yields more than one row, it is all concatenated, with a newline between the data for each row. -.section "More about MySQL, PostgreSQL, Oracle, and InterBase" "SECID72" +.section "More about MySQL, PostgreSQL, Oracle, InterBase, and Redis" "SECID72" .cindex "MySQL" "lookup type" .cindex "PostgreSQL lookup type" .cindex "lookup" "MySQL" @@ -7294,13 +7541,18 @@ with a newline between the data for each row. .cindex "lookup" "Oracle" .cindex "InterBase lookup type" .cindex "lookup" "InterBase" -If any MySQL, PostgreSQL, Oracle, or InterBase lookups are used, the -&%mysql_servers%&, &%pgsql_servers%&, &%oracle_servers%&, or &%ibase_servers%& +.cindex "Redis lookup type" +.cindex lookup Redis +If any MySQL, PostgreSQL, Oracle, InterBase or Redis lookups are used, the +&%mysql_servers%&, &%pgsql_servers%&, &%oracle_servers%&, &%ibase_servers%&, +or &%redis_servers%& option (as appropriate) must be set to a colon-separated list of server information. -(For MySQL and PostgreSQL only, the global option need not be set if all +(For MySQL and PostgreSQL, the global option need not be set if all queries contain their own server information &-- see section -&<>&.) Each item in the list is a slash-separated list of four +&<>&.) +For all but Redis +each item in the list is a slash-separated list of four items: host name, database name, user name, and password. In the case of Oracle, the host name field is used for the &"service name"&, and the database name field is not used and should be empty. For example: @@ -7321,16 +7573,36 @@ a query is successfully processed. The result of a query may be that no data is found, but that is still a successful query. In other words, the list of servers provides a backup facility, not a list of different places to look. +.new +For Redis the global option need not be specified if all queries contain their +own server information &-- see section &<>&. +If specified, the option must be set to a colon-separated list of server +information. +Each item in the list is a slash-separated list of three items: +host, database number, and password. +.olist +The host is required and may be either an IPv4 address and optional +port number (separated by a colon, which needs doubling due to the +higher-level list), or a Unix socket pathname enclosed in parentheses +.next +The database number is optional; if present that number is selected in the backend +.next +The password is optional; if present it is used to authenticate to the backend +.endlist +.wen + +.new The &%quote_mysql%&, &%quote_pgsql%&, and &%quote_oracle%& expansion operators convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b respectively, and the characters single-quote, double-quote, and backslash -itself are escaped with backslashes. The &%quote_pgsql%& expansion operator, in -addition, escapes the percent and underscore characters. This cannot be done -for MySQL because these escapes are not recognized in contexts where these -characters are not special. +itself are escaped with backslashes. + +The &%quote_redis%& expansion operator +escapes whitespace and backslash characters with a backslash. +.wen .section "Specifying the server in the query" "SECTspeserque" -For MySQL and PostgreSQL lookups (but not currently for Oracle and InterBase), +For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase), it is possible to specify a list of servers with an individual query. This is done by starting the query with .display @@ -7373,13 +7645,17 @@ ${lookup pgsql{servers=master/db/name/pw; UPDATE ...} } .section "Special MySQL features" "SECID73" For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%& causes a connection to the server on the local host by means of a Unix domain -socket. An alternate socket can be specified in parentheses. The full syntax of -each item in &%mysql_servers%& is: +socket. An alternate socket can be specified in parentheses. +.new +An option group name for MySQL option files can be specified in square brackets; +the default value is &"exim"&. +.wen +The full syntax of each item in &%mysql_servers%& is: .display -<&'hostname'&>::<&'port'&>(<&'socket name'&>)/<&'database'&>/&&& - <&'user'&>/<&'password'&> +<&'hostname'&>::<&'port'&>(<&'socket name'&>)[<&'option group'&>]/&&& + <&'database'&>/<&'user'&>/<&'password'&> .endd -Any of the three sub-parts of the first field can be omitted. For normal use on +Any of the four sub-parts of the first field can be omitted. For normal use on the local host it can be left blank or set to just &"localhost"&. No database need be supplied &-- but if it is absent here, it must be given in @@ -7425,12 +7701,14 @@ ${lookup sqlite {/some/thing/sqlitedb \ .endd In a list, the syntax is similar. For example: .code -domainlist relay_domains = sqlite;/some/thing/sqlitedb \ +domainlist relay_to_domains = sqlite;/some/thing/sqlitedb \ select * from relays where ip='$sender_host_address'; .endd The only character affected by the &%quote_sqlite%& operator is a single quote, which it doubles. +.cindex timeout SQLite +.cindex sqlite "lookup timeout" The SQLite library handles multiple simultaneous accesses to the database internally. Multiple readers are permitted, but only one process can update at once. Attempts to access the database while it is being updated @@ -7460,9 +7738,13 @@ host, email address, or local part, respectively. In the sections below, the different types of pattern for each case are described, but first we cover some general facilities that apply to all four kinds of list. +Note that other parts of Exim use a &'string list'& which does not +support all the complexity available in +domain, host, address and local part lists. + -.section "Expansion of lists" "SECID75" +.section "Expansion of lists" "SECTlistexpand" .cindex "expansion" "of lists" Each list is expanded as a single string before it is used. The result of expansion must be a list, possibly containing empty items, which is split up @@ -7507,13 +7789,13 @@ subject is not in the set. If the end of the list is reached without the subject having matched any of the patterns, it is in the set if the last item was a negative one, but not if it was a positive one. For example, the list in .code -domainlist relay_domains = !a.b.c : *.b.c +domainlist relay_to_domains = !a.b.c : *.b.c .endd matches any domain ending in &'.b.c'& except for &'a.b.c'&. Domains that match neither &'a.b.c'& nor &'*.b.c'& do not match, because the last item in the list is positive. However, if the setting were .code -domainlist relay_domains = !a.b.c +domainlist relay_to_domains = !a.b.c .endd then all domains other than &'a.b.c'& would match because the last item in the list is negative. In other words, a list that ends with a negative item behaves @@ -7617,7 +7899,7 @@ the words &%domainlist%&, &%hostlist%&, &%addresslist%&, or &%localpartlist%&, respectively. Then there follows the name that you are defining, followed by an equals sign and the list itself. For example: .code -hostlist relay_hosts = 192.168.23.0/24 : my.friend.example +hostlist relay_from_hosts = 192.168.23.0/24 : my.friend.example addresslist bad_senders = cdb;/etc/badsenders .endd A named list may refer to other named lists: @@ -8084,7 +8366,7 @@ case the IP address is used on its own. There are several types of pattern that require Exim to know the name of the remote host. These are either wildcard patterns or lookups by name. (If a complete hostname is given without any wildcarding, it is used to find an IP -address to match against, as described in the section &<>& +address to match against, as described in section &<>& above.) If the remote host name is not already known when Exim encounters one of these @@ -8164,10 +8446,13 @@ apply to temporary DNS errors, whose handling is described in the next section. .cindex "&`+include_unknown`&" .cindex "&`+ignore_unknown`&" -By default, Exim behaves as if the host does not match the list. This may not -always be what you want to happen. To change Exim's behaviour, the special -items &`+include_unknown`& or &`+ignore_unknown`& may appear in the list (at -top level &-- they are not recognized in an indirected file). +Exim parses a host list from left to right. If it encounters a permanent +lookup failure in any item in the host list before it has found a match, +Exim treats it as a failure and the default behavior is as if the host +does not match the list. This may not always be what you want to happen. +To change Exim's behaviour, the special items &`+include_unknown`& or +&`+ignore_unknown`& may appear in the list (at top level &-- they are +not recognized in an indirected file). .ilist If any item that follows &`+include_unknown`& requires information that @@ -8195,6 +8480,42 @@ Both &`+include_unknown`& and &`+ignore_unknown`& may appear in the same list. The effect of each one lasts until the next, or until the end of the list. +.section "Mixing wildcarded host names and addresses in host lists" &&& + "SECTmixwilhos" +.cindex "host list" "mixing names and addresses in" + +This section explains the host/ip processing logic with the same concepts +as the previous section, but specifically addresses what happens when a +wildcarded hostname is one of the items in the hostlist. + +.ilist +If you have name lookups or wildcarded host names and +IP addresses in the same host list, you should normally put the IP +addresses first. For example, in an ACL you could have: +.code +accept hosts = 10.9.8.7 : *.friend.example +.endd +The reason you normally would order it this way lies in the +left-to-right way that Exim processes lists. It can test IP addresses +without doing any DNS lookups, but when it reaches an item that requires +a host name, it fails if it cannot find a host name to compare with the +pattern. If the above list is given in the opposite order, the +&%accept%& statement fails for a host whose name cannot be found, even +if its IP address is 10.9.8.7. + +.next +If you really do want to do the name check first, and still recognize the IP +address, you can rewrite the ACL like this: +.code +accept hosts = *.friend.example +accept hosts = 10.9.8.7 +.endd +If the first &%accept%& fails, Exim goes on to try the second one. See chapter +&<>& for details of ACLs. Alternatively, you can use +&`+ignore_unknown`&, which was discussed in depth in the first example in +this section. +.endlist + .section "Temporary DNS errors when looking up host information" &&& "SECTtemdnserr" @@ -8203,7 +8524,7 @@ list. .cindex "&`+ignore_defer`&" A temporary DNS lookup failure normally causes a defer action (except when &%dns_again_means_nonexist%& converts it into a permanent error). However, -host lists can include &`+ignore_defer`& and &`+include_defer`&, analagous to +host lists can include &`+ignore_defer`& and &`+include_defer`&, analogous to &`+ignore_unknown`& and &`+include_unknown`&, as described in the previous section. These options should be used with care, probably only in non-critical host lists such as whitelists. @@ -8253,7 +8574,7 @@ use masked IP addresses in database queries, you can use the &%mask%& expansion operator. If the query contains a reference to &$sender_host_name$&, Exim automatically -looks up the host name if has not already done so. (See section +looks up the host name if it has not already done so. (See section &<>& for comments on finding host names.) Historical note: prior to release 4.30, Exim would always attempt to find a @@ -8265,33 +8586,6 @@ See section &<>&.) -.section "Mixing wildcarded host names and addresses in host lists" &&& - "SECTmixwilhos" -.cindex "host list" "mixing names and addresses in" -If you have name lookups or wildcarded host names and IP addresses in the same -host list, you should normally put the IP addresses first. For example, in an -ACL you could have: -.code -accept hosts = 10.9.8.7 : *.friend.example -.endd -The reason for this lies in the left-to-right way that Exim processes lists. -It can test IP addresses without doing any DNS lookups, but when it reaches an -item that requires a host name, it fails if it cannot find a host name to -compare with the pattern. If the above list is given in the opposite order, the -&%accept%& statement fails for a host whose name cannot be found, even if its -IP address is 10.9.8.7. - -If you really do want to do the name check first, and still recognize the IP -address, you can rewrite the ACL like this: -.code -accept hosts = *.friend.example -accept hosts = 10.9.8.7 -.endd -If the first &%accept%& fails, Exim goes on to try the second one. See chapter -&<>& for details of ACLs. - - - .section "Address lists" "SECTaddresslist" @@ -8453,7 +8747,7 @@ but the separating colon must still be included at line breaks. White space surrounding the colons is ignored. For example: .code aol.com: spammer1 : spammer2 : ^[0-9]+$ : -spammer3 : spammer4 + spammer3 : spammer4 .endd As in all colon-separated lists in Exim, a colon can be included in an item by doubling. @@ -8698,6 +8992,88 @@ string easier to understand. This item inserts &"basic"& header lines. It is described with the &%header%& expansion item below. + +.vitem "&*${acl{*&<&'name'&>&*}{*&<&'arg'&>&*}...}*&" +.cindex "expansion" "calling an acl" +.cindex "&%acl%&" "call from expansion" +The name and zero to nine argument strings are first expanded separately. The expanded +arguments are assigned to the variables &$acl_arg1$& to &$acl_arg9$& in order. +Any unused are made empty. The variable &$acl_narg$& is set to the number of +arguments. The named ACL (see chapter &<>&) is called +and may use the variables; if another acl expansion is used the values +are restored after it returns. If the ACL sets +a value using a "message =" modifier and returns accept or deny, the value becomes +the result of the expansion. +If no message is set and the ACL returns accept or deny +the expansion result is an empty string. +If the ACL returns defer the result is a forced-fail. Otherwise the expansion fails. + + +.vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&& + {*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&" +.cindex "expansion" "extracting cerificate fields" +.cindex "&%certextract%&" "certificate fields" +.cindex "certificate" "extracting fields" +The <&'certificate'&> must be a variable of type certificate. +The field name is expanded and used to retrieve the relevant field from +the certificate. Supported fields are: +.display +&`version `& +&`serial_number `& +&`subject `& RFC4514 DN +&`issuer `& RFC4514 DN +&`notbefore `& time +&`notafter `& time +&`sig_algorithm `& +&`signature `& +&`subj_altname `& tagged list +&`ocsp_uri `& list +&`crl_uri `& list +.endd +If the field is found, +<&'string2'&> is expanded, and replaces the whole item; +otherwise <&'string3'&> is used. During the expansion of <&'string2'&> the +variable &$value$& contains the value that has been extracted. Afterwards, it +is restored to any previous value it might have had. + +If {<&'string3'&>} is omitted, the item is replaced by an empty string if the +key is not found. If {<&'string2'&>} is also omitted, the value that was +extracted is used. + +Some field names take optional modifiers, appended and separated by commas. + +The field selectors marked as "RFC4514" above +output a Distinguished Name string which is +not quite +parseable by Exim as a comma-separated tagged list +(the exceptions being elements containing commas). +RDN elements of a single type may be selected by +a modifier of the type label; if so the expansion +result is a list (newline-separated by default). +The separator may be changed by another modifier of +a right angle-bracket followed immediately by the new separator. +Recognised RDN type labels include "CN", "O", "OU" and "DC". + +The field selectors marked as "time" above +take an optional modifier of "int" +for which the result is the number of seconds since epoch. +Otherwise the result is a human-readable string +in the timezone selected by the main "timezone" option. + +The field selectors marked as "list" above return a list, +newline-separated by default, +(embedded separator characters in elements are doubled). +The separator may be changed by a modifier of +a right angle-bracket followed immediately by the new separator. + +The field selectors marked as "tagged" above +prefix each list element with a type string and an equals sign. +Elements of only one type may be selected by a modifier +which is one of "dns", "uri" or "mail"; +if so the element tags are omitted. + +If not otherwise noted field values are presented in human-readable form. + .vitem "&*${dlfunc{*&<&'file'&>&*}{*&<&'function'&>&*}{*&<&'arg'&>&*}&&& {*&<&'arg'&>&*}...}*&" .cindex &%dlfunc%& @@ -8736,6 +9112,30 @@ When compiling a function that is to be used in this way with gcc, you need to add &%-shared%& to the gcc command. Also, in the Exim build-time configuration, you must add &%-export-dynamic%& to EXTRALIBS. + +.vitem "&*${env{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&" +.cindex "expansion" "extracting value from environment" +.cindex "environment" "value from" +The key is first expanded separately, and leading and trailing white space +removed. +This is then searched for as a name in the environment. +If a variable is found then its value is placed in &$value$& +and <&'string1'&> is expanded, otherwise <&'string2'&> is expanded. + +Instead of {<&'string2'&>} the word &"fail"& (not in curly brackets) can +appear, for example: +.code +${env{USER}{$value} fail } +.endd +This forces an expansion failure (see section &<>&); +{<&'string1'&>} must be present for &"fail"& to be recognized. + +If {<&'string2'&>} is omitted an empty string is substituted on +search failure. +If {<&'string1'&>} is omitted the search result is substituted on +search success. + + .vitem "&*${extract{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}&&& {*&<&'string3'&>&*}}*&" .cindex "expansion" "extracting substrings by key" @@ -8935,10 +9335,11 @@ by earlier ACLs are visible. Upper case and lower case letters are synonymous in header names. If the following character is white space, the terminating colon may be omitted, but this is not recommended, because you may then forget it when it is needed. When -white space terminates the header name, it is included in the expanded string. -If the message does not contain the given header, the expansion item is -replaced by an empty string. (See the &%def%& condition in section -&<>& for a means of testing for the existence of a header.) +white space terminates the header name, this white space is included in the +expanded string. If the message does not contain the given header, the +expansion item is replaced by an empty string. (See the &%def%& condition in +section &<>& for a means of testing for the existence of a +header.) If there is more than one header with the same name, they are all concatenated to form the substitution string, up to a maximum length of 64K. Unless @@ -9014,6 +9415,19 @@ you can use condition = ${if >{$acl_m4}{3}} .endd + + +.new +.vitem &*${imapfolder{*&<&'foldername'&>&*}}*& +.cindex expansion "imap folder" +.cindex "&%imapfolder%& expansion item" +This item converts a (possibly multilevel, or with non-ASCII characters) +folder specification to a Maildir name for filesystem use. +For information on internationalisation support see &<>&. +.wen + + + .vitem &*${length{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*& .cindex "expansion" "string truncation" .cindex "&%length%& expansion item" @@ -9030,6 +9444,44 @@ of <&'string2'&>, whichever is the shorter. Do not confuse &%length%& with &%strlen%&, which gives the length of a string. +.vitem "&*${listextract{*&<&'number'&>&*}&&& + {*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&" +.cindex "expansion" "extracting list elements by number" +.cindex "&%listextract%&" "extract list elements by number" +.cindex "list" "extracting elements by number" +The <&'number'&> argument must consist entirely of decimal digits, +apart from an optional leading minus, +and leading and trailing white space (which is ignored). + +After expansion, <&'string1'&> is interpreted as a list, colon-separated by +default, but the separator can be changed in the usual way. + +The first field of the list is numbered one. +If the number is negative, the fields are +counted from the end of the list, with the rightmost one numbered -1. +The numbered element of the list is extracted and placed in &$value$&, +then <&'string2'&> is expanded as the result. + +If the modulus of the +number is zero or greater than the number of fields in the string, +the result is the expansion of <&'string3'&>. + +For example: +.code +${listextract{2}{x:42:99}} +.endd +yields &"42"&, and +.code +${listextract{-3}{<, x,42,99,& Mailer,,/bin/bash}{result: $value}} +.endd +yields &"result: 42"&. + +If {<&'string3'&>} is omitted, an empty string is used for string3. +If {<&'string2'&>} is also omitted, the value that was +extracted is used. +You can use &`fail`& instead of {<&'string3'&>} as in a string extract. + + .vitem "&*${lookup{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&& {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" This is the first of one of two different types of lookup item, which are both @@ -9211,7 +9663,7 @@ locks out the use of this expansion item in filter files. .cindex "expansion" "inserting from a socket" .cindex "socket, use of in expansion" .cindex "&%readsocket%& expansion item" -This item inserts data from a Unix domain or Internet socket into the expanded +This item inserts data from a Unix domain or TCP socket into the expanded string. The minimal way of using it uses just two arguments, as in these examples: .code @@ -9230,7 +9682,8 @@ ${readsocket{inet:[::1]:1234}{request string}} Only a single host name may be given, but if looking it up yields more than one IP address, they are each tried in turn until a connection is made. For both kinds of socket, Exim makes a connection, writes the request string -(unless it is an empty string) and reads from the socket until an end-of-file +unless it is an empty string; and no terminating NUL is ever sent) +and reads from the socket until an end-of-file is read. A timeout of 5 seconds is applied. Additional, optional arguments extend what can be done. Firstly, you can vary the timeout. For example: .code @@ -9307,11 +9760,23 @@ expansion item above. {*&<&'string2'&>&*}}*&" .cindex "expansion" "running a command" .cindex "&%run%& expansion item" -The command and its arguments are first expanded separately, and then the -command is run in a separate process, but under the same uid and gid. As in -other command executions from Exim, a shell is not used by default. If you want +The command and its arguments are first expanded as one string. The string is +split apart into individual arguments by spaces, and then the command is run +in a separate process, but under the same uid and gid. As in other command +executions from Exim, a shell is not used by default. If the command requires a shell, you must explicitly code it. +Since the arguments are split by spaces, when there is a variable expansion +which has an empty result, it will cause the situation that the argument will +simply be omitted when the program is actually executed by Exim. If the +script/program requires a specific number of arguments and the expanded +variable could possibly result in this empty expansion, the variable must be +quoted. This is more difficult if the expanded variable itself could result +in a string containing quotes, because it would interfere with the quotes +around the command arguments. A possible guard against this is to wrap the +variable in the &%sg%& operator to change any quote marks to some other +character. + The standard input for the command exists, but is empty. The standard output and standard error are set to the same file descriptor. .cindex "return code" "from &%run%& expansion" @@ -9328,6 +9793,20 @@ can be the word &"fail"& (not in braces) to force expansion failure if the command does not succeed. If both strings are omitted, the result is contents of the standard output/error on success, and nothing on failure. +.vindex "&$run_in_acl$&" +The standard output/error of the command is put in the variable &$value$&. +In this ACL example, the output of a command is logged for the admin to +troubleshoot: +.code +warn condition = ${run{/usr/bin/id}{yes}{no}} + log_message = Output of id: $value +.endd +If the command requires shell idioms, such as the > redirect operator, the +shell must be invoked directly, such as with: +.code +${run{/bin/bash -c "/usr/bin/id >/tmp/id"}{yes}{yes}} +.endd + .vindex "&$runrc$&" The return code from the command is put in the variable &$runrc$&, and this remains set afterwards, so in a filter file you can do things like this: @@ -9376,6 +9855,36 @@ the regular expression from string expansion. +.vitem &*${sort{*&<&'string'&>&*}{*&<&'comparator'&>&*}{*&<&'extractor'&>&*}}*& +.cindex sorting "a list" +.cindex list sorting +.cindex expansion "list sorting" +After expansion, <&'string'&> is interpreted as a list, colon-separated by +default, but the separator can be changed in the usual way. +The <&'comparator'&> argument is interpreted as the operator +of a two-argument expansion condition. +The numeric operators plus ge, gt, le, lt (and ~i variants) are supported. +The comparison should return true when applied to two values +if the first value should sort before the second value. +The <&'extractor'&> expansion is applied repeatedly to elements of the list, +the element being placed in &$item$&, +to give values for comparison. + +The item result is a sorted list, +with the original list separator, +of the list elements (in full) of the original. + +Examples: +.code +${sort{3:2:1:4}{<}{$item}} +.endd +sorts a list of numbers, and +.code +${sort {${lookup dnsdb{>:,,mx=example.com}}} {<} {${listextract{1}{<,$item}}}} +.endd +will sort an MX lookup into priority order. + + .vitem &*${substr{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*& .cindex "&%substr%& expansion item" .cindex "substring extraction" @@ -9488,6 +9997,29 @@ expansion item, which extracts the working address from a single RFC2822 address. See the &*filter*&, &*map*&, and &*reduce*& items for ways of processing lists. +To clarify "list of addresses in RFC 2822 format" mentioned above, Exim follows +a strict interpretation of header line formatting. Exim parses the bare, +unquoted portion of an email address and if it finds a comma, treats it as an +email address separator. For the example header line: +.code +From: =?iso-8859-2?Q?Last=2C_First?= +.endd +The first example below demonstrates that Q-encoded email addresses are parsed +properly if it is given the raw header (in this example, &`$rheader_from:`&). +It does not see the comma because it's still encoded as "=2C". The second +example below is passed the contents of &`$header_from:`&, meaning it gets +de-mimed. Exim sees the decoded "," so it treats it as &*two*& email addresses. +The third example shows that the presence of a comma is skipped when it is +quoted. +.code +# exim -be '${addresses:From: \ +=?iso-8859-2?Q?Last=2C_First?= }' +user@example.com +# exim -be '${addresses:From: Last, First }' +Last:user@example.com +# exim -be '${addresses:From: "Last, First" }' +user@example.com +.endd .vitem &*${base62:*&<&'digits'&>&*}*& .cindex "&%base62%& expansion item" @@ -9507,6 +10039,26 @@ environments where Exim uses base 36 instead of base 62 for its message identifiers, base-36 digits. The number is converted to decimal and output as a string. +.new +.vitem &*${base64:*&<&'string'&>&*}*& +.cindex "expansion" "base64 encoding" +.cindex "base64 encoding" "in string expansion" +.cindex "&%base64%& expansion item" +.cindex certificate "base64 of DER" +This operator converts a string into one that is base64 encoded. + +If the string is a single variable of type certificate, +returns the base64 encoding of the DER form of the certificate. + + +.vitem &*${base64d:*&<&'string'&>&*}*& +.cindex "expansion" "base64 decoding" +.cindex "base64 decoding" "in string expansion" +.cindex "&%base64d%& expansion item" +This operator converts a base64-encoded string into the un-coded form. +.wen + + .vitem &*${domain:*&<&'string'&>&*}*& .cindex "domain" "extraction" .cindex "expansion" "domain extraction" @@ -9641,6 +10193,37 @@ This operator converts a hex string into one that is base64 encoded. This can be useful for processing the output of the MD5 and SHA-1 hashing functions. + +.vitem &*${hexquote:*&<&'string'&>&*}*& +.cindex "quoting" "hex-encoded unprintable characters" +.cindex "&%hexquote%& expansion item" +This operator converts non-printable characters in a string into a hex +escape form. Byte values between 33 (!) and 126 (~) inclusive are left +as is, and other byte values are converted to &`\xNN`&, for example a +byte value 127 is converted to &`\x7f`&. + + +.new +.vitem &*${ipv6denorm:*&<&'string'&>&*}*& +.cindex "&%ipv6denorm%& expansion item" +.cindex "IP address" normalisation +This expands an IPv6 address to a full eight-element colon-separated set +of hex digits including leading zeroes. +A trailing ipv4-style dotted-decimal set is converted to hex. +Pure IPv4 addresses are converted to IPv4-mapped IPv6. + +.vitem &*${ipv6norm:*&<&'string'&>&*}*& +.cindex "&%ipv6norm%& expansion item" +.cindex "IP address" normalisation +.cindex "IP address" "canonical form" +This converts an IPv6 address to canonical form. +Leading zeroes of groups are omitted, and the longest +set of zero-valued groups is replaced with a double colon. +A trailing ipv4-style dotted-decimal set is converted to hex. +Pure IPv4 addresses are converted to IPv4-mapped IPv6. +.wen + + .vitem &*${lc:*&<&'string'&>&*}*& .cindex "case forcing in strings" .cindex "string" "case forcing" @@ -9666,6 +10249,25 @@ See the description of the general &%length%& item above for details. Note that when &%length%& is used as an operator. +.vitem &*${listcount:*&<&'string'&>&*}*& +.cindex "expansion" "list item count" +.cindex "list" "item count" +.cindex "list" "count of items" +.cindex "&%listcount%& expansion item" +The string is interpreted as a list and the number of items is returned. + + +.vitem &*${listnamed:*&<&'name'&>&*}*&&~and&~&*${listnamed_*&<&'type'&>&*:*&<&'name'&>&*}*& +.cindex "expansion" "named list" +.cindex "&%listnamed%& expansion item" +The name is interpreted as a named list and the content of the list is returned, +expanding any referenced lists, re-quoting as needed for colon-separation. +If the optional type is given it must be one of "a", "d", "h" or "l" +and selects address-, domain-, host- or localpart- lists to search among respectively. +Otherwise all types are searched in an undefined order and the first +matching list is returned. + + .vitem &*${local_part:*&<&'string'&>&*}*& .cindex "expansion" "local part extraction" .cindex "&%local_part%& expansion item" @@ -9705,10 +10307,14 @@ Letters in IPv6 addresses are always output in lower case. .vitem &*${md5:*&<&'string'&>&*}*& .cindex "MD5 hash" .cindex "expansion" "MD5 hash" +.cindex certificate fingerprint .cindex "&%md5%& expansion item" The &%md5%& operator computes the MD5 hash value of the string, and returns it as a 32-digit hexadecimal number, in which any letters are in lower case. +If the string is a single variable of type certificate, +returns the MD5 hash fingerprint of the certificate. + .vitem &*${nhash_*&<&'n'&>&*_*&<&'m'&>&*:*&<&'string'&>&*}*& .cindex "expansion" "numeric hash" @@ -9773,10 +10379,8 @@ This operator returns a somewhat random number which is less than the supplied number and is at least 0. The quality of this randomness depends on how Exim was built; the values are not suitable for keying material. If Exim is linked against OpenSSL then RAND_pseudo_bytes() is used. -.new If Exim is linked against GnuTLS then gnutls_rnd(GNUTLS_RND_NONCE) is used, for versions of GnuTLS with that function. -.wen Otherwise, the implementation may be arc4random(), random() seeded by srandomdev() or srandom(), or a custom implementation even weaker than random(). @@ -9785,17 +10389,17 @@ random(). .vitem &*${reverse_ip:*&<&'ipaddr'&>&*}*& .cindex "expansion" "IP address" This operator reverses an IP address; for IPv4 addresses, the result is in -dotted-quad decimal form, while for IPv6 addreses the result is in +dotted-quad decimal form, while for IPv6 addresses the result is in dotted-nibble hexadecimal form. In both cases, this is the "natural" form for DNS. For example, .code ${reverse_ip:192.0.2.4} -${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3} +${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.127} .endd returns .code 4.2.0.192 -3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2 +f.7.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2 .endd @@ -9806,7 +10410,7 @@ returns This operator encodes text according to the rules of RFC 2047. This is an encoding that is used in header lines to encode non-ASCII characters. It is assumed that the input string is in the encoding specified by the -&%headers_charset%& option, which defaults to ISO-8859-1. If the string +&%headers_charset%& option, which gets its default at build time. If the string contains only characters in the range 33&--126, and no instances of the characters .code @@ -9844,10 +10448,26 @@ variables or headers inside regular expressions. .vitem &*${sha1:*&<&'string'&>&*}*& .cindex "SHA-1 hash" .cindex "expansion" "SHA-1 hashing" +.cindex certificate fingerprint .cindex "&%sha2%& expansion item" The &%sha1%& operator computes the SHA-1 hash value of the string, and returns it as a 40-digit hexadecimal number, in which any letters are in upper case. +If the string is a single variable of type certificate, +returns the SHA-1 hash fingerprint of the certificate. + + +.vitem &*${sha256:*&<&'certificate'&>&*}*& +.cindex "SHA-256 hash" +.cindex certificate fingerprint +.cindex "expansion" "SHA-256 hashing" +.cindex "&%sha256%& expansion item" +The &%sha256%& operator computes the SHA-256 hash fingerprint of the +certificate, +and returns +it as a 64-digit hexadecimal number, in which any letters are in upper case. +Only arguments which are a single variable of certificate type are supported. + .vitem &*${stat:*&<&'string'&>&*}*& .cindex "expansion" "statting a file" @@ -9868,10 +10488,10 @@ the system administrator. &*Warning*&: The file size may be incorrect on 32-bit systems for files larger than 2GB. .vitem &*${str2b64:*&<&'string'&>&*}*& -.cindex "expansion" "base64 encoding" -.cindex "base64 encoding" "in string expansion" .cindex "&%str2b64%& expansion item" -This operator converts a string into one that is base64 encoded. +.new +Now deprecated, a synonym for the &%base64%& expansion operator. +.wen @@ -9917,6 +10537,31 @@ number of larger units and output in Exim's normal time format, for example, .cindex "expansion" "case forcing" .cindex "&%uc%& expansion item" This forces the letters in the string into upper-case. + +.vitem &*${utf8clean:*&<&'string'&>&*}*& +.cindex "correction of invalid utf-8 sequences in strings" +.cindex "utf-8" "utf-8 sequences" +.cindex "incorrect utf-8" +.cindex "expansion" "utf-8 forcing" +.cindex "&%utf8clean%& expansion item" +This replaces any invalid utf-8 sequence in the string by the character &`?`&. + +.new +.vitem "&*${utf8_domain_to_alabel:*&<&'string'&>&*}*&" &&& + "&*${utf8_domain_from_alabel:*&<&'string'&>&*}*&" &&& + "&*${utf8_localpart_to_alabel:*&<&'string'&>&*}*&" &&& + "&*${utf8_localpart_from_alabel:*&<&'string'&>&*}*&" +.cindex expansion UTF-8 +.cindex UTF-8 expansion +.cindex EAI +.cindex internationalisation +.cindex "&%utf8_domain_to_alabel%& expansion item" +.cindex "&%utf8_domain_from_alabel%& expansion item" +.cindex "&%utf8_localpart_to_alabel%& expansion item" +.cindex "&%utf8_localpart_from_alabel%& expansion item" +These convert EAI mail name components between UTF-8 and a-label forms. +For information on internationalisation support see &<>&. +.wen .endlist @@ -9955,8 +10600,8 @@ ${if >{$message_size}{10M} ... .endd Note that the general negation operator provides for inequality testing. The two strings must take the form of optionally signed decimal integers, -optionally followed by one of the letters &"K"& or &"M"& (in either upper or -lower case), signifying multiplication by 1024 or 1024*1024, respectively. +optionally followed by one of the letters &"K"&, &"M"& or &"G"& (in either upper or +lower case), signifying multiplication by 1024, 1024*1024 or 1024*1024*1024, respectively. As a special case, the numerical value of an empty string is taken as zero. @@ -9965,12 +10610,27 @@ In all cases, a relative comparator OP is testing if <&'string1'&> OP 10M, not if 10M is larger than &$message_size$&. +.vitem &*acl&~{{*&<&'name'&>&*}{*&<&'arg1'&>&*}&&& + {*&<&'arg2'&>&*}...}*& +.cindex "expansion" "calling an acl" +.cindex "&%acl%&" "expansion condition" +The name and zero to nine argument strings are first expanded separately. The expanded +arguments are assigned to the variables &$acl_arg1$& to &$acl_arg9$& in order. +Any unused are made empty. The variable &$acl_narg$& is set to the number of +arguments. The named ACL (see chapter &<>&) is called +and may use the variables; if another acl expansion is used the values +are restored after it returns. If the ACL sets +a value using a "message =" modifier the variable $value becomes +the result of the expansion, otherwise it is empty. +If the ACL returns accept the condition is true; if deny, false. +If the ACL returns defer the result is a forced-fail. + .vitem &*bool&~{*&<&'string'&>&*}*& .cindex "expansion" "boolean parsing" .cindex "&%bool%& expansion condition" This condition turns a string holding a true or false representation into a boolean state. It parses &"true"&, &"false"&, &"yes"& and &"no"& -(case-insensitively); also positive integer numbers map to true if non-zero, +(case-insensitively); also integer numbers map to true if non-zero, false if zero. An empty string is treated as false. Leading and trailing whitespace is ignored; @@ -10159,6 +10819,8 @@ ${if forany{<, $recipients}{match{$item}{^user3@}}{yes}{no}} The value of &$item$& is saved and restored while &*forany*& or &*forall*& is being processed, to enable these expansion items to be nested. +To scan a named list, expand it with the &*listnamed*& operator. + .vitem &*ge&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&& &*gei&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& @@ -10182,7 +10844,6 @@ string is lexically greater than the second string. For &%gt%& the comparison includes the case of letters, whereas for &%gti%& the comparison is case-independent. -.new .vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&& &*inlisti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& .cindex "string" "comparison" @@ -10199,7 +10860,6 @@ ${if inlist{needle}{foo:needle:bar}} ${if inlisti{Needle}{fOo:NeeDLE:bAr}} ${if forany{fOo:NeeDLE:bAr}{eqi{$item}{Needle}}} .endd -.wen .vitem &*isip&~{*&<&'string'&>&*}*& &&& &*isip4&~{*&<&'string'&>&*}*& &&& @@ -10311,12 +10971,10 @@ See &*match_local_part*&. .vitem &*match_ip&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& .cindex "&%match_ip%& expansion condition" -.new This condition matches an IP address to a list of IP address patterns. It must be followed by two argument strings. The first (after expansion) must be an IP address or an empty string. The second (not expanded) is a restricted host list that can match only an IP address, not a host name. For example: -.wen .code ${if match_ip{$sender_host_address}{1.2.3.4:5.6.7.8}{...}{...}} .endd @@ -10362,10 +11020,8 @@ just as easy to use the fact that a lookup is itself a condition, and write: .endd .endlist ilist -.new Note that <&'string2'&> is not itself subject to string expansion, unless Exim was built with the EXPAND_LISTMATCH_RHS option. -.wen Consult section &<>& for further details of these patterns. @@ -10394,10 +11050,8 @@ item can be used, as in all address lists, to cause subsequent items to have their local parts matched casefully. Domains are always matched caselessly. -.new Note that <&'string2'&> is not itself subject to string expansion, unless Exim was built with the EXPAND_LISTMATCH_RHS option. -.wen &*Note*&: Host lists are &'not'& supported in this way. This is because hosts have two identities: a name and an IP address, and it is not clear @@ -10604,13 +11258,19 @@ support for TLS or the content scanning extension. When a &%match%& expansion condition succeeds, these variables contain the captured substrings identified by the regular expression during subsequent processing of the success string of the containing &%if%& expansion item. -However, they do not retain their values afterwards; in fact, their previous +In the expansion condition case +they do not retain their values afterwards; in fact, their previous values are restored at the end of processing an &%if%& item. The numerical variables may also be set externally by some other matching process which precedes the expansion of the string. For example, the commands available in Exim filter files include an &%if%& command with its own regular expression matching condition. +.vitem "&$acl_arg1$&, &$acl_arg2$&, etc" +Within an acl condition, expansion condition or expansion item +any arguments are copied to these variables, +any unused variables being made empty. + .vitem "&$acl_c...$&" Values can be placed in these variables by the &%set%& modifier in an ACL. They can be given any name that starts with &$acl_c$& and is at least six characters @@ -10632,6 +11292,10 @@ message is received, the values of these variables are saved with the message, and can be accessed by filters, routers, and transports during subsequent delivery. +.vitem &$acl_narg$& +Within an acl condition, expansion condition or expansion item +this variable has the number of arguments. + .vitem &$acl_verify_message$& .vindex "&$acl_verify_message$&" After an address verification has failed, this variable contains the failure @@ -10694,7 +11358,7 @@ this variable holds the pipe command when the transport is running. .vitem "&$auth1$& &-- &$auth3$&" .vindex "&$auth1$&, &$auth2$&, etc" These variables are used in SMTP authenticators (see chapters -&<>&&--&<>&). Elsewhere, they are empty. +&<>&&--&<>&). Elsewhere, they are empty. .vitem &$authenticated_id$& .cindex "authentication" "id" @@ -10710,7 +11374,16 @@ the value of &$authenticated_id$& is normally the login name of the calling process. However, a trusted user can override this by means of the &%-oMai%& command line option. - +.vitem &$authenticated_fail_id$& +.cindex "authentication" "fail" "id" +.vindex "&$authenticated_fail_id$&" +When an authentication attempt fails, the variable &$authenticated_fail_id$& +will contain the failed authentication id. If more than one authentication +id is attempted, it will contain only the last one. The variable is +available for processing in the ACL's, generally the quit or notquit ACL. +A message to a local recipient could still be accepted without requiring +authentication, which means this variable could also be visible in all of +the ACL's as well. .vitem &$authenticated_sender$& @@ -10744,14 +11417,12 @@ is empty and &$authentication_failed$& is set to &"1"&). Failure includes any negative response to an AUTH command, including (for example) an attempt to use an undefined mechanism. -.new .vitem &$av_failed$& .cindex "content scanning" "AV scanner failure" This variable is available when Exim is compiled with the content-scanning extension. It is set to &"0"& by default, but will be set to &"1"& if any problem occurs with the virus scanner (specified by &%av_scanner%&) during the ACL malware condition. -.wen .vitem &$body_linecount$& .cindex "message body" "line count" @@ -10796,9 +11467,10 @@ not the same as the user id of the originator of a message (see &$originator_uid$&). If Exim re-execs itself, this variable in the new incarnation normally contains the Exim uid. -.vitem &$compile_date$& -.vindex "&$compile_date$&" -The date on which the Exim binary was compiled. +.vitem &$callout_address$& +.vindex "&$callout_address$&" +After a callout for verification, spamd or malware daemon service, the +address that was connected to. .vitem &$compile_number$& .vindex "&$compile_number$&" @@ -10806,6 +11478,17 @@ The building process for Exim keeps a count of the number of times it has been compiled. This serves to distinguish different compilations of the same version of the program. +.vitem &$config_dir$& +.vindex "&$config_dir$&" +The directory name of the main configuration file. That is, the content of +&$config_file$& with the last component stripped. The value does not +contain the trailing slash. If &$config_file$& does not contain a slash, +&$config_dir$& is ".". + +.vitem &$config_file$& +.vindex "&$config_file$&" +The name of the main configuration file Exim is using. + .vitem &$demime_errorlevel$& .vindex "&$demime_errorlevel$&" This variable is available when Exim is compiled with @@ -10818,6 +11501,35 @@ This variable is available when Exim is compiled with the content-scanning extension and the obsolete &%demime%& condition. For details, see section &<>&. +.vitem &$dkim_cur_signer$& &&& + &$dkim_verify_status$& &&& + &$dkim_verify_reason$& &&& + &$dkim_domain$& &&& + &$dkim_identity$& &&& + &$dkim_selector$& &&& + &$dkim_algo$& &&& + &$dkim_canon_body$& &&& + &$dkim_canon_headers$& &&& + &$dkim_copiedheaders$& &&& + &$dkim_bodylength$& &&& + &$dkim_created$& &&& + &$dkim_expires$& &&& + &$dkim_headernames$& &&& + &$dkim_key_testing$& &&& + &$dkim_key_nosubdomains$& &&& + &$dkim_key_srvtype$& &&& + &$dkim_key_granularity$& &&& + &$dkim_key_notes$& &&& + &$dkim_key_length$& +These variables are only available within the DKIM ACL. +For details see chapter &<>&. + +.vitem &$dkim_signers$& +.vindex &$dkim_signers$& +When a message has been received this variable contains +a colon-separated list of signer domains and identities for the message. +For details see chapter &<>&. + .vitem &$dnslist_domain$& &&& &$dnslist_matched$& &&& &$dnslist_text$& &&& @@ -10913,6 +11625,13 @@ This variable contains the path to the Exim binary. .vindex "&$exim_uid$&" This variable contains the numerical value of the Exim user id. +.vitem &$exim_version$& +.vindex "&$exim_version$&" +This variable contains the version string of the Exim build. +The first character is a major version number, currently 4. +Then after a dot, the next group of digits is a minor version number. +There may be other characters following the minor version. + .vitem &$found_extension$& .vindex "&$found_extension$&" This variable is available when Exim is compiled with the @@ -10925,6 +11644,12 @@ inserting the message header line with the given name. Note that the name must be terminated by colon or white space, because it may contain a wide variety of characters. Note also that braces must &'not'& be used. +.vitem &$headers_added$& +.vindex "&$headers_added$&" +Within an ACL this variable contains the headers added so far by +the ACL modifier add_header (section &<>&). +The headers are a newline-separated list. + .vitem &$home$& .vindex "&$home$&" When the &%check_local_user%& option is set for a router, the user's home @@ -11005,6 +11730,11 @@ the result, the name is not accepted, and &$host_lookup_deferred$& is set to .vindex "&$host_lookup_failed$&" See &$host_lookup_deferred$&. +.vitem &$host_port$& +.vindex "&$host_port$&" +This variable is set to the remote host's TCP port whenever &$host$& is set +for an outbound connection. + .vitem &$inode$& .vindex "&$inode$&" @@ -11157,6 +11887,18 @@ ability to find the amount of free space (only true for experimental systems), the space value is -1. See also the &%check_log_space%& option. +.vitem &$lookup_dnssec_authenticated$& +.vindex "&$lookup_dnssec_authenticated$&" +This variable is set after a DNS lookup done by +a dnsdb lookup expansion, dnslookup router or smtp transport. +.cindex "DNS" "DNSSEC" +It will be empty if &(DNSSEC)& was not requested, +&"no"& if the result was not labelled as authenticated data +and &"yes"& if it was. +Results that are labelled as authoritative answer that match +the &%dns_trust_aa%& configuration variable count also +as authenticated data. + .vitem &$mailstore_basename$& .vindex "&$mailstore_basename$&" This variable is set only when doing deliveries in &"mailstore"& format in the @@ -11243,7 +11985,7 @@ This variable is like &$message_headers$& except that no processing of the contents of header lines is done. .vitem &$message_id$& -This is an old name for &$message_exim_id$&, which is now deprecated. +This is an old name for &$message_exim_id$&. It is now deprecated. .vitem &$message_linecount$& .vindex "&$message_linecount$&" @@ -11388,6 +12130,24 @@ a single-component name, Exim calls &[gethostbyname()]& (or qualified host name. See also &$smtp_active_hostname$&. +.new +.vitem &$proxy_host_address$& &&& + &$proxy_host_port$& &&& + &$proxy_target_address$& &&& + &$proxy_target_port$& &&& + &$proxy_session$& +These variables are only available when built with Proxy Protocol +or Socks5 support +For details see chapter &<>&. +.wen + +.new +.vitem &$prdr_requested$& +.cindex "PRDR" "variable for" +This variable is set to &"yes"& if PRDR was requested by the client for the +current message, otherwise &"no"&. +.wen + .vitem &$prvscheck_address$& This variable is used in conjunction with the &%prvscheck%& expansion item, which is described in sections &<>& and @@ -11460,10 +12220,7 @@ on which interface and/or port is being used for the incoming connection. The values of &$received_ip_address$& and &$received_port$& are saved with any messages that are received, thus making these variables available at delivery time. - -&*Note:*& There are no equivalent variables for outgoing connections, because -the values are unknown (unless they are explicitly set by options of the -&(smtp)& transport). +For outbound connections see &$sending_ip_address$&. .vitem &$received_port$& .vindex "&$received_port$&" @@ -11569,6 +12326,12 @@ increases for each accepted recipient. It can be referenced in an ACL. This variable is set to contain the matching regular expression after a &%regex%& ACL condition has matched (see section &<>&). +.vitem "&$regex1$&, &$regex2$&, etc" +.cindex "regex submatch variables (&$1regex$& &$2regex$& etc)" +When a &%regex%& or &%mime_regex%& ACL condition succeeds, +these variables contain the +captured substrings identified by the regular expression. + .vitem &$reply_address$& .vindex "&$reply_address$&" @@ -11595,6 +12358,12 @@ envelope sender. .vindex "&$return_size_limit$&" This is an obsolete name for &$bounce_return_size_limit$&. +.vitem &$router_name$& +.cindex "router" "name" +.cindex "name" "of router" +.vindex "&$router_name$&" +During the running of a router this variable contains its name. + .vitem &$runrc$& .cindex "return code" "from &%run%& expansion" .vindex "&$runrc$&" @@ -11667,6 +12436,12 @@ verification either failed or was not requested. A host name in parentheses is the argument of a HELO or EHLO command. This is omitted if it is identical to the verified host name or to the host's IP address in square brackets. +.vitem &$sender_helo_dnssec$& +.vindex "&$sender_helo_dnssec$&" +This boolean variable is true if a successful HELO verification was +.cindex "DNS" "DNSSEC" +done using DNS information the resolver library stated was authenticated data. + .vitem &$sender_helo_name$& .vindex "&$sender_helo_name$&" When a message is received from a remote host that has issued a HELO or EHLO @@ -11676,8 +12451,9 @@ the &%-bs%& or &%-bS%& options. .vitem &$sender_host_address$& .vindex "&$sender_host_address$&" -When a message is received from a remote host, this variable contains that -host's IP address. For locally submitted messages, it is empty. +When a message is received from a remote host using SMTP, +this variable contains that +host's IP address. For locally non-SMTP submitted messages, it is empty. .vitem &$sender_host_authenticated$& .vindex "&$sender_host_authenticated$&" @@ -11686,6 +12462,29 @@ driver that successfully authenticated the client from which the message was received. It is empty if there was no successful authentication. See also &$authenticated_id$&. +.vitem &$sender_host_dnssec$& +.vindex "&$sender_host_dnssec$&" +If an attempt to populate &$sender_host_name$& has been made +(by reference, &%hosts_lookup%& or +otherwise) then this boolean will have been set true if, and only if, the +resolver library states that both +the reverse and forward DNS were authenticated data. At all +other times, this variable is false. + +.cindex "DNS" "DNSSEC" +It is likely that you will need to coerce DNSSEC support on in the resolver +library, by setting: +.code +dns_dnssec_ok = 1 +.endd + +Exim does not perform DNSSEC validation itself, instead leaving that to a +validating resolver (e.g. unbound, or bind with suitable configuration). + +If you have changed &%host_lookup_order%& so that &`bydns`& is not the first +mechanism in the list, then this variable will be false. + + .vitem &$sender_host_name$& .vindex "&$sender_host_name$&" When a message is received from a remote host, this variable contains the @@ -11884,22 +12683,78 @@ command in a filter file. Its use is explained in the description of that command, which can be found in the separate document entitled &'Exim's interfaces to mail filtering'&. -.new -.vitem &$tls_bits$& -.vindex "&$tls_bits$&" -Contains an approximation of the TLS cipher's bit-strength; the meaning of +.vitem &$tls_in_bits$& +.vindex "&$tls_in_bits$&" +Contains an approximation of the TLS cipher's bit-strength +on the inbound connection; the meaning of this depends upon the TLS implementation used. If TLS has not been negotiated, the value will be 0. The value of this is automatically fed into the Cyrus SASL authenticator when acting as a server, to specify the "external SSF" (a SASL term). -.wen -.vitem &$tls_certificate_verified$& -.vindex "&$tls_certificate_verified$&" +The deprecated &$tls_bits$& variable refers to the inbound side +except when used in the context of an outbound SMTP delivery, when it refers to +the outbound. + +.vitem &$tls_out_bits$& +.vindex "&$tls_out_bits$&" +Contains an approximation of the TLS cipher's bit-strength +on an outbound SMTP connection; the meaning of +this depends upon the TLS implementation used. +If TLS has not been negotiated, the value will be 0. + +.vitem &$tls_in_ourcert$& +.vindex "&$tls_in_ourcert$&" +.cindex certificate veriables +This variable refers to the certificate presented to the peer of an +inbound connection when the message was received. +It is only useful as the argument of a +&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator, +or a &%def%& condition. + +.vitem &$tls_in_peercert$& +.vindex "&$tls_in_peercert$&" +This variable refers to the certificate presented by the peer of an +inbound connection when the message was received. +It is only useful as the argument of a +&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator, +or a &%def%& condition. +If certificate verification fails it may refer to a failing chain element +which is not the leaf. + +.vitem &$tls_out_ourcert$& +.vindex "&$tls_out_ourcert$&" +This variable refers to the certificate presented to the peer of an +outbound connection. It is only useful as the argument of a +&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator, +or a &%def%& condition. + +.vitem &$tls_out_peercert$& +.vindex "&$tls_out_peercert$&" +This variable refers to the certificate presented by the peer of an +outbound connection. It is only useful as the argument of a +&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator, +or a &%def%& condition. +If certificate verification fails it may refer to a failing chain element +which is not the leaf. + +.vitem &$tls_in_certificate_verified$& +.vindex "&$tls_in_certificate_verified$&" This variable is set to &"1"& if a TLS certificate was verified when the message was received, and &"0"& otherwise. -.vitem &$tls_cipher$& +The deprecated &$tls_certificate_verified$& variable refers to the inbound side +except when used in the context of an outbound SMTP delivery, when it refers to +the outbound. + +.vitem &$tls_out_certificate_verified$& +.vindex "&$tls_out_certificate_verified$&" +This variable is set to &"1"& if a TLS certificate was verified when an +outbound SMTP connection was made, +and &"0"& otherwise. + +.vitem &$tls_in_cipher$& +.vindex "&$tls_in_cipher$&" .vindex "&$tls_cipher$&" When a message is received from a remote host over an encrypted SMTP connection, this variable is set to the cipher suite that was negotiated, for @@ -11908,24 +12763,62 @@ received over unencrypted connections, the variable is empty. Testing &$tls_cipher$& for emptiness is one way of distinguishing between encrypted and non-encrypted connections during ACL processing. -The &$tls_cipher$& variable retains its value during message delivery, except -when an outward SMTP delivery takes place via the &(smtp)& transport. In this -case, &$tls_cipher$& is cleared before any outgoing SMTP connection is made, +The deprecated &$tls_cipher$& variable is the same as &$tls_in_cipher$& during message reception, +but in the context of an outward SMTP delivery taking place via the &(smtp)& transport +becomes the same as &$tls_out_cipher$&. + +.vitem &$tls_out_cipher$& +.vindex "&$tls_out_cipher$&" +This variable is +cleared before any outgoing SMTP connection is made, and then set to the outgoing cipher suite if one is negotiated. See chapter &<>& for details of TLS support and chapter &<>& for details of the &(smtp)& transport. -.vitem &$tls_peerdn$& +.vitem &$tls_in_ocsp$& +.vindex "&$tls_in_ocsp$&" +When a message is received from a remote client connection +the result of any OCSP request from the client is encoded in this variable: +.code +0 OCSP proof was not requested (default value) +1 No response to request +2 Response not verified +3 Verification failed +4 Verification succeeded +.endd + +.vitem &$tls_out_ocsp$& +.vindex "&$tls_out_ocsp$&" +When a message is sent to a remote host connection +the result of any OCSP request made is encoded in this variable. +See &$tls_in_ocsp$& for values. + +.vitem &$tls_in_peerdn$& +.vindex "&$tls_in_peerdn$&" .vindex "&$tls_peerdn$&" +.cindex certificate "extracting fields" When a message is received from a remote host over an encrypted SMTP connection, and Exim is configured to request a certificate from the client, the value of the Distinguished Name of the certificate is made available in the -&$tls_peerdn$& during subsequent processing. Like &$tls_cipher$&, the -value is retained during message delivery, except during outbound SMTP -deliveries. +&$tls_in_peerdn$& during subsequent processing. +If certificate verification fails it may refer to a failing chain element +which is not the leaf. + +The deprecated &$tls_peerdn$& variable refers to the inbound side +except when used in the context of an outbound SMTP delivery, when it refers to +the outbound. + +.vitem &$tls_out_peerdn$& +.vindex "&$tls_out_peerdn$&" +When a message is being delivered to a remote host over an encrypted SMTP +connection, and Exim is configured to request a certificate from the server, +the value of the Distinguished Name of the certificate is made available in the +&$tls_out_peerdn$& during subsequent processing. +If certificate verification fails it may refer to a failing chain element +which is not the leaf. -.new -.vitem &$tls_sni$& +.vitem &$tls_in_sni$& +.vindex "&$tls_in_sni$&" .vindex "&$tls_sni$&" .cindex "TLS" "Server Name Indication" When a TLS session is being established, if the client sends the Server @@ -11936,10 +12829,16 @@ will be re-expanded early in the TLS session, to permit a different certificate to be presented (and optionally a different key to be used) to the client, based upon the value of the SNI extension. -The value will be retained for the lifetime of the message. During outbound -SMTP deliveries, it reflects the value of the &%tls_sni%& option on +The deprecated &$tls_sni$& variable refers to the inbound side +except when used in the context of an outbound SMTP delivery, when it refers to +the outbound. + +.vitem &$tls_out_sni$& +.vindex "&$tls_out_sni$&" +.cindex "TLS" "Server Name Indication" +During outbound +SMTP deliveries, this variable reflects the value of the &%tls_sni%& option on the transport. -.wen .vitem &$tod_bsdinbox$& .vindex "&$tod_bsdinbox$&" @@ -11982,12 +12881,25 @@ This variable contains the numerical value of the local timezone, for example: This variable contains the UTC date and time in &"Zulu"& format, as specified by ISO 8601, for example: 20030221154023Z. +.vitem &$transport_name$& +.cindex "transport" "name" +.cindex "name" "of transport" +.vindex "&$transport_name$&" +During the running of a transport, this variable contains its name. + .vitem &$value$& .vindex "&$value$&" This variable contains the result of an expansion lookup, extraction operation, or external command, as described above. It is also used during a &*reduce*& expansion. +.vitem &$verify_mode$& +.vindex "&$verify_mode$&" +While a router or transport is being run in verify mode +or for cutthrough delivery, +contains "S" for sender-verification or "R" for recipient-verification. +Otherwise, empty. + .vitem &$version_number$& .vindex "&$version_number$&" The version number of Exim. @@ -12199,8 +13111,9 @@ option), the interfaces and ports on which it listens are controlled by the following options: .ilist -&%daemon_smtp_ports%& contains a list of default ports. (For backward -compatibility, this option can also be specified in the singular.) +&%daemon_smtp_ports%& contains a list of default ports +or service names. +(For backward compatibility, this option can also be specified in the singular.) .next &%local_interfaces%& contains list of interface IP addresses on which to listen. Each item may optionally also specify a port. @@ -12301,7 +13214,8 @@ value of &%daemon_smtp_ports%& is no longer relevant in this example.) Exim supports the obsolete SSMTP protocol (also known as SMTPS) that was used before the STARTTLS command was standardized for SMTP. Some legacy clients still use this protocol. If the &%tls_on_connect_ports%& option is set to a -list of port numbers, connections to those ports must use SSMTP. The most +list of port numbers or service names, +connections to those ports must use SSMTP. The most common use of this option is expected to be .code tls_on_connect_ports = 465 @@ -12393,7 +13307,7 @@ local_interfaces = 0.0.0.0 : 127.0.0.1.26 .endd To specify listening on the default port on specific interfaces only: .code -local_interfaces = 192.168.34.67 : 192.168.34.67 +local_interfaces = 10.0.0.67 : 192.168.34.67 .endd &*Warning*&: Such a setting excludes listening on the loopback interfaces. @@ -12525,6 +13439,7 @@ listed in more than one group. .section "Logging" "SECID99" .table2 +.row &%event_action%& "custom logging" .row &%hosts_connection_nolog%& "exemption from connect logging" .row &%log_file_path%& "override compiled-in value" .row &%log_selector%& "set/unset optional logging" @@ -12532,6 +13447,7 @@ listed in more than one group. .row &%message_logs%& "create per-message logs" .row &%preserve_message_logs%& "after message completion" .row &%process_log_path%& "for SIGUSR1 and &'exiwhat'&" +.row &%slow_lookup_log%& "control logging of slow DNS lookups" .row &%syslog_duplication%& "controls duplicate log lines on syslog" .row &%syslog_facility%& "set syslog &""facility""& field" .row &%syslog_processname%& "set syslog &""ident""& field" @@ -12637,6 +13553,7 @@ listed in more than one group. .row &%acl_smtp_auth%& "ACL for AUTH" .row &%acl_smtp_connect%& "ACL for connection" .row &%acl_smtp_data%& "ACL for DATA" +.row &%acl_smtp_data_prdr%& "ACL for DATA, per-recipient" .row &%acl_smtp_dkim%& "ACL for DKIM verification" .row &%acl_smtp_etrn%& "ACL for ETRN" .row &%acl_smtp_expn%& "ACL for EXPN" @@ -12644,6 +13561,7 @@ listed in more than one group. .row &%acl_smtp_mail%& "ACL for MAIL" .row &%acl_smtp_mailauth%& "ACL for AUTH on MAIL command" .row &%acl_smtp_mime%& "ACL for MIME parts" +.row &%acl_smtp_notquit%& "ACL for non-QUIT terminations" .row &%acl_smtp_predata%& "ACL for start of data" .row &%acl_smtp_quit%& "ACL for QUIT" .row &%acl_smtp_rcpt%& "ACL for RCPT" @@ -12663,6 +13581,7 @@ listed in more than one group. .row &%helo_verify_hosts%& "HELO hard-checked for these hosts" .row &%host_lookup%& "host name looked up for these hosts" .row &%host_lookup_order%& "order of DNS and local name lookups" +.row &%hosts_proxy%& "use proxy protocol for these hosts" .row &%host_reject_connection%& "reject connection from these hosts" .row &%hosts_treat_as_local%& "useful in some cluster configurations" .row &%local_scan_timeout%& "timeout for &[local_scan()]&" @@ -12690,12 +13609,15 @@ listed in more than one group. .section "TLS" "SECID108" .table2 .row &%gnutls_compat_mode%& "use GnuTLS compatibility mode" +.row &%gnutls_allow_auto_pkcs11%& "allow GnuTLS to autoload PKCS11 modules" .row &%openssl_options%& "adjust OpenSSL compatibility options" .row &%tls_advertise_hosts%& "advertise TLS to these hosts" .row &%tls_certificate%& "location of server certificate" .row &%tls_crl%& "certificate revocation list" .row &%tls_dh_max_bits%& "clamp D-H bit count suggestion" .row &%tls_dhparam%& "DH parameters for server" +.row &%tls_eccurve%& "EC curve selection for server" +.row &%tls_ocsp_file%& "location of server certificate status proof" .row &%tls_on_connect_ports%& "specify SSMTP (SMTPS) ports" .row &%tls_privatekey%& "location of server private key" .row &%tls_remember_esmtp%& "don't reset after starting TLS" @@ -12749,6 +13671,7 @@ listed in more than one group. See also the &'Policy controls'& section above. .table2 +.row &%dkim_verify_signers%& "DKIM domain for which DKIM ACL is run" .row &%host_lookup%& "host name looked up for these hosts" .row &%host_lookup_order%& "order of DNS and local name lookups" .row &%recipient_unqualified_hosts%& "may send unqualified recipients" @@ -12788,9 +13711,12 @@ See also the &'Policy controls'& section above. .table2 .row &%accept_8bitmime%& "advertise 8BITMIME" .row &%auth_advertise_hosts%& "advertise AUTH to these hosts" +.row &%dsn_advertise_hosts%& "advertise DSN extensions to these hosts" .row &%ignore_fromline_hosts%& "allow &""From ""& from these hosts" .row &%ignore_fromline_local%& "allow &""From ""& from local SMTP" .row &%pipelining_advertise_hosts%& "advertise pipelining to these hosts" +.row &%prdr_enable%& "advertise PRDR to all hosts" +.row &%smtputf8_advertise_hosts%& "advertise SMTPUTF8 to these hosts" .row &%tls_advertise_hosts%& "advertise TLS to these hosts" .endtable @@ -12836,9 +13762,11 @@ See also the &'Policy controls'& section above. .row &%disable_ipv6%& "do no IPv6 processing" .row &%dns_again_means_nonexist%& "for broken domains" .row &%dns_check_names_pattern%& "pre-DNS syntax check" +.row &%dns_dnssec_ok%& "parameter for resolver" .row &%dns_ipv4_lookup%& "only v4 lookup for these domains" .row &%dns_retrans%& "parameter for resolver" .row &%dns_retry%& "parameter for resolver" +.row &%dns_trust_aa%& "DNS zones trusted as authentic" .row &%dns_use_edns0%& "parameter for resolver" .row &%hold_domains%& "hold delivery for these domains" .row &%local_interfaces%& "for routing checks" @@ -12864,6 +13792,7 @@ See also the &'Policy controls'& section above. .row &%bounce_message_file%& "content of bounce" .row &%bounce_message_text%& "content of bounce" .row &%bounce_return_body%& "include body if returning message" +.row &%bounce_return_linesize_limit%& "limit on returned message line length" .row &%bounce_return_message%& "include original message in bounce" .row &%bounce_return_size_limit%& "limit on returned message" .row &%bounce_sender_authentication%& "send authenticated sender with bounce" @@ -12883,10 +13812,11 @@ See also the &'Policy controls'& section above. Those options that undergo string expansion before use are marked with †. -.new .option accept_8bitmime main boolean true .cindex "8BITMIME" .cindex "8-bit characters" +.cindex "log" "selectors" +.cindex "log" "8BITMIME" This option causes Exim to send 8BITMIME in its response to an SMTP EHLO command, and to accept the BODY= parameter on MAIL commands. However, though Exim is 8-bit clean, it is not a protocol converter, and it @@ -12899,7 +13829,11 @@ A more detailed analysis of the issues is provided by Dan Bernstein: .display &url(http://cr.yp.to/smtp/8bitmime.html) .endd -.wen + +To log received 8BITMIME status use +.code +log_selector = +8bitmime +.endd .option acl_not_smtp main string&!! unset .cindex "&ACL;" "for non-SMTP messages" @@ -12936,6 +13870,23 @@ This option defines the ACL that is run after an SMTP DATA command has been processed and the message itself has been received, but before the final acknowledgment is sent. See chapter &<>& for further details. +.option acl_smtp_data_prdr main string&!! accept +.cindex "PRDR" "ACL for" +.cindex "DATA" "PRDR ACL for" +.cindex "&ACL;" "PRDR-related" +.cindex "&ACL;" "per-user data processing" +This option defines the ACL that, +if the PRDR feature has been negotiated, +is run for each recipient after an SMTP DATA command has been +processed and the message itself has been received, but before the +acknowledgment is sent. See chapter &<>& for further details. + +.option acl_smtp_dkim main string&!! unset +.cindex DKIM "ACL for" +This option defines the ACL that is run for each DKIM signature +of a received message. +See chapter &<>& for further details. + .option acl_smtp_etrn main string&!! unset .cindex "ETRN" "ACL for" This option defines the ACL that is run when an SMTP ETRN command is @@ -12970,6 +13921,12 @@ This option is available when Exim is built with the content-scanning extension. It defines the ACL that is run for each MIME part in a message. See section &<>& for details. +.option acl_smtp_notquit main string&!! unset +.cindex "not-QUIT, ACL for" +This option defines the ACL that is run when an SMTP session +ends without a QUIT command being received. +See chapter &<>& for further details. + .option acl_smtp_predata main string&!! unset This option defines the ACL that is run when an SMTP DATA command is received, before the message itself is received. See chapter &<>& for @@ -12995,6 +13952,14 @@ received. See chapter &<>& for further details. This option defines the ACL that is run when an SMTP VRFY command is received. See chapter &<>& for further details. +.new +.option add_environment main "string list" empty +.cindex "environment" "inherited" +This option allows to set individual environment variables that the +currently linked libraries and programs in child processes use. The +default list is empty, +.wen + .option admin_groups main "string list&!!" unset .cindex "admin user" This option is expanded just once, at the start of Exim's processing. If the @@ -13026,7 +13991,7 @@ the local host's IP addresses. It appears that more and more DNS zone administrators are breaking the rules and putting domain names that look like IP addresses on the right hand side of MX records. Exim follows the rules and rejects this, giving an error message -that explains the mis-configuration. However, some other MTAs support this +that explains the misconfiguration. However, some other MTAs support this practice, so to avoid &"Why can't Exim do this?"& complaints, &%allow_mx_to_ip%& exists, in order to enable this heinous activity. It is not recommended, except when you have no other choice. @@ -13080,10 +14045,10 @@ If you want to advertise the availability of AUTH only when the connection is encrypted using TLS, you can make use of the fact that the value of this option is expanded, with a setting like this: .code -auth_advertise_hosts = ${if eq{$tls_cipher}{}{}{*}} +auth_advertise_hosts = ${if eq{$tls_in_cipher}{}{}{*}} .endd -.vindex "&$tls_cipher$&" -If &$tls_cipher$& is empty, the session is not encrypted, and the result of +.vindex "&$tls_in_cipher$&" +If &$tls_in_cipher$& is empty, the session is not encrypted, and the result of the expansion is empty, thus matching no hosts. Otherwise, the result of the expansion is *, which matches all hosts. @@ -13144,6 +14109,24 @@ error that is detected during reception, only those header lines preceding the point at which the error was detected are returned. .cindex "bounce message" "including original" +.option bounce_return_linesize_limit main integer 998 +.cindex "size" "of bounce lines, limit" +.cindex "bounce message" "line length limit" +.cindex "limit" "bounce message line length" +This option sets a limit in bytes on the line length of messages +that are returned to senders due to delivery problems, +when &%bounce_return_message%& is true. +The default value corresponds to RFC limits. +If the message being returned has lines longer than this value it is +treated as if the &%bounce_return_size_limit%& (below) restriction was exceeded. + +The option also applies to bounces returned when an error is detected +during reception of a messsage. +In this case lines from the original are truncated. + +The option does not apply to messages generated by an &(autoreply)& transport. + + .option bounce_return_message main boolean true If this option is set false, none of the original message is included in bounce messages generated by Exim. See also &%bounce_return_size_limit%& and @@ -13330,6 +14313,9 @@ a very large time at the end of the list. For example: .code delay_warning = 2h:12h:99d .endd +Note that the option is only evaluated at the time a delivery attempt fails, +which depends on retry and queue-runner configuration. +Typically retries will be configured more frequently than warning messages. .option delay_warning_condition main string&!! "see below" .vindex "&$domain$&" @@ -13402,6 +14388,14 @@ etc. are ignored. If IP literals are enabled, the &(ipliteral)& router declines to handle IPv6 literal addresses. +.option dkim_verify_signers main "domain list&!!" $dkim_signers +.cindex DKIM "controlling calls to the ACL" +This option gives a list of DKIM domains for which the DKIM ACL is run. +It is expanded after the message is received; by default it runs +the ACL once for each signature in the message. +See chapter &<>&. + + .option dns_again_means_nonexist main "domain list&!!" unset .cindex "DNS" "&""try again""& response; overriding" DNS lookups give a &"try again"& response for the DNS errors @@ -13451,6 +14445,17 @@ This option controls whether or not an IP address, given as a CSA domain, is reversed and looked up in the reverse DNS, as described in more detail in section &<>&. + +.option dns_dnssec_ok main integer -1 +.cindex "DNS" "resolver options" +.cindex "DNS" "DNSSEC" +If this option is set to a non-negative number then Exim will initialise the +DNS resolver library to either use or not use DNSSEC, overriding the system +default. A value of 0 coerces DNSSEC off, a value of 1 coerces DNSSEC on. + +If the resolver library does not support DNSSEC then this option has no effect. + + .option dns_ipv4_lookup main "domain list&!!" unset .cindex "IPv6" "DNS lookup for AAAA records" .cindex "DNS" "IPv6 lookup for AAAA records" @@ -13466,6 +14471,8 @@ servers have all been upgraded, there should be no need for this option. .option dns_retrans main time 0s .cindex "DNS" "resolver options" +.cindex timeout "dns lookup" +.cindex "DNS" timeout The options &%dns_retrans%& and &%dns_retry%& can be used to set the retransmission and retry parameters for DNS lookups. Values of zero (the defaults) leave the system default settings unchanged. The first value is the @@ -13475,13 +14482,39 @@ take. I haven't found any documentation about timeouts on DNS lookups; these parameter values are available in the external resolver interface structure, but nowhere does it seem to describe how they are used or what you might want to set in them. +See also the &%slow_lookup_log%& option. .option dns_retry main integer 0 See &%dns_retrans%& above. -.new +.option dns_trust_aa main "domain list&!!" unset +.cindex "DNS" "resolver options" +.cindex "DNS" "DNSSEC" +If this option is set then lookup results marked with the AA bit +(Authoritative Answer) are trusted the same way as if they were +DNSSEC-verified. The authority section's name of the answer must +match with this expanded domain list. + +Use this option only if you talk directly to a resolver that is +authoritative for some zones and does not set the AD (Authentic Data) +bit in the answer. Some DNS servers may have an configuration option to +mark the answers from their own zones as verified (they set the AD bit). +Others do not have this option. It is considered as poor practice using +a resolver that is an authoritative server for some zones. + +Use this option only if you really have to (e.g. if you want +to use DANE for remote delivery to a server that is listed in the DNS +zones that your resolver is authoritative for). + +If the DNS answer packet has the AA bit set and contains resource record +in the answer section, the name of the first NS record appearing in the +authority section is compared against the list. If the answer packet is +authoritative but the answer section is empty, the name of the first SOA +record in the authoritative section is used instead. + +.cindex "DNS" "resolver options" .option dns_use_edns0 main integer -1 .cindex "DNS" "resolver options" .cindex "DNS" "EDNS0" @@ -13491,7 +14524,6 @@ the system default. A value of 0 coerces EDNS0 off, a value of 1 coerces EDNS0 on. If the resolver library does not support EDNS0 then this option has no effect. -.wen .option drop_cr main boolean false @@ -13499,6 +14531,18 @@ This is an obsolete option that is now a no-op. It used to affect the way Exim handled CR and LF characters in incoming messages. What happens now is described in section &<>&. +.option dsn_advertise_hosts main "host list&!!" unset +.cindex "bounce messages" "success" +.cindex "DSN" "success" +.cindex "Delivery Status Notification" "success" +DSN extensions (RFC3461) will be advertised in the EHLO message to, +and accepted from, these hosts. +Hosts may use the NOTIFY and ENVID options on RCPT TO commands, +and RET and ORCPT options on MAIL FROM commands. +A NOTIFY=SUCCESS option requests success-DSN messages. +A NOTIFY= option with no argument requests that no delay or failure DSNs +are sent. + .option dsn_from main "string&!!" "see below" .cindex "&'From:'& header line" "in bounces" .cindex "bounce messages" "&'From:'& line, specifying" @@ -13516,7 +14560,7 @@ panic is logged, and the default value is used. Exim's transports have an option for adding an &'Envelope-to:'& header to a message when it is delivered, in exactly the same way as &'Return-path:'& is handled. &'Envelope-to:'& records the original recipient address from the -messages's envelope that caused the delivery to happen. Such headers should not +message's envelope that caused the delivery to happen. Such headers should not be present in incoming messages, and this option causes them to be removed at the time the message is received, to avoid any problems that might occur when a delivered message is subsequently sent on to some other recipient. @@ -13576,6 +14620,14 @@ own &'Reply-To:'& header line, the value of the &%errors_reply_to%& option is not used. +.new +.option event_action main string&!! unset +.cindex events +This option declares a string to be expanded for Exim's events mechanism. +For details see &<>&. +.wen + + .option exim_group main string "compile-time configured" .cindex "gid (group id)" "Exim's own" .cindex "Exim group" @@ -13623,7 +14675,7 @@ routing, but which are not used for listening by the daemon. See section . Allow this long option name to split; give it unsplit as a fifth argument . for the automatic .oindex that is generated by .option. -.option "extract_addresses_remove_ &~&~arguments" main boolean true &&& +.option "extract_addresses_remove_arguments" main boolean true &&& extract_addresses_remove_arguments .oindex "&%-t%&" .cindex "command line" "addresses with &%-t%&" @@ -13707,6 +14759,17 @@ This option controls whether GnuTLS is used in compatibility mode in an Exim server. This reduces security slightly, but improves interworking with older implementations of TLS. + +option gnutls_allow_auto_pkcs11 main boolean unset +This option will let GnuTLS (2.12.0 or later) autoload PKCS11 modules with +the p11-kit configuration files in &_/etc/pkcs11/modules/_&. + +See +&url(http://www.gnutls.org/manual/gnutls.html#Smart-cards-and-HSMs) +for documentation. + + + .option headers_charset main string "see below" This option sets a default character set for translating from encoded MIME &"words"& in header lines, when referenced by an &$h_xxx$& expansion item. The @@ -13796,14 +14859,17 @@ is an IP literal matching the calling address of the host, or matches the host name that Exim obtains by doing a reverse lookup of the calling host address, or .next -when looked up using &[gethostbyname()]& (or &[getipnodebyname()]& when -available) yields the calling host address. +when looked up in DNS yields the calling host address. .endlist However, the EHLO or HELO command is not rejected if any of the checks fail. Processing continues, but the result of the check is remembered, and can be detected later in an ACL by the &`verify = helo`& condition. +If DNS was used for successful verification, the variable +.cindex "DNS" "DNSSEC" +&$helo_verify_dnssec$& records the DNSSEC status of the lookups. + .option helo_verify_hosts main "host list&!!" unset .cindex "HELO verifying" "mandatory" .cindex "EHLO" "verifying, mandatory" @@ -13907,6 +14973,14 @@ If the &%smtp_connection%& log selector is not set, this option has no effect. +.new +.option hosts_proxy main "host list&!!" unset +.cindex proxy "proxy protocol" +This option enables use of Proxy Protocol proxies for incoming +connections. For details see &<>&. +.wen + + .option hosts_treat_as_local main "domain list&!!" unset .cindex "local host" "domains treated as" .cindex "host" "treated as local" @@ -13973,6 +15047,30 @@ process rather than a remote host, and is using &%-bs%& to inject the messages, .option ignore_fromline_local main boolean false See &%ignore_fromline_hosts%& above. +.new +.option keep_environment main "string list" unset +.cindex "environment" "inherited" +This option contains a string list of environment variables to keep. +You have to trust these variables or you have to be sure that +these variables do not impose any security risk. Keep in mind that +during the startup phase Exim is running with an effective UID 0 in most +installations. As the default value is an empty list, the default +environment for using libraries, running embedded Perl code, or running +external binaries is empty, and does not not even contain PATH or HOME. + +Actually the list is interpreted as a list of patterns +(&<>&), except that it is not expanded first. + +WARNING: Macro substitution is still done first, so having a macro +FOO and having FOO_HOME in your &%keep_environment%& option may have +unexpected results. You may work around this using a regular expression +that does not match the macro name: ^[F]OO_HOME$. + +Current versions of Exim issue a warning during startupif you do not mention +&%keep_environment%& or &%add_environment%& in your runtime configuration +file. +.wen + .option keep_malformed main time 4d This option specifies the length of time to keep messages whose spool files @@ -13983,6 +15081,7 @@ logged. .option ldap_ca_cert_dir main string unset .cindex "LDAP", "TLS CA certificate directory" +.cindex certificate "directory for LDAP" This option indicates which directory contains CA certificates for verifying a TLS certificate presented by an LDAP server. While Exim does not provide a default value, your SSL library may. @@ -13992,6 +15091,7 @@ and constrained to be a directory. .option ldap_ca_cert_file main string unset .cindex "LDAP", "TLS CA certificate file" +.cindex certificate "file for LDAP" This option indicates which file contains CA certificates for verifying a TLS certificate presented by an LDAP server. While Exim does not provide a default value, your SSL library may. @@ -14001,6 +15101,7 @@ and constrained to be a file. .option ldap_cert_file main string unset .cindex "LDAP" "TLS client certificate file" +.cindex certificate "file for LDAP" This option indicates which file contains an TLS client certificate which Exim should present to the LDAP server during TLS negotiation. Should be used together with &%ldap_cert_key%&. @@ -14008,6 +15109,7 @@ Should be used together with &%ldap_cert_key%&. .option ldap_cert_key main string unset .cindex "LDAP" "TLS client key file" +.cindex certificate "key for LDAP" This option indicates which file contains the secret/private key to use to prove identity to the LDAP server during TLS negotiation. Should be used together with &%ldap_cert_file%&, which contains the @@ -14177,8 +15279,9 @@ section &<>&. This option sets the path which is used to determine the names of Exim's log files, or indicates that logging is to be to syslog, or both. It is expanded when Exim is entered, so it can, for example, contain a reference to the host -name. If no specific path is set for the log files at compile or run time, they -are written in a sub-directory called &_log_& in Exim's spool directory. +name. If no specific path is set for the log files at compile or run time, +or if the option is unset at run time (i.e. &`log_file_path = `&) +they are written in a sub-directory called &_log_& in Exim's spool directory. Chapter &<>& contains further details about Exim's logging, and section &<>& describes how the contents of &%log_file_path%& are used. If this string is fixed at your installation (contains no expansion @@ -14325,7 +15428,7 @@ If you use a virus-scanner and set this option to to a value larger than the maximum size that your virus-scanner is configured to support, you may get failures triggered by large mails. The right size to configure for the virus-scanner depends upon what data is passed and the options in use but it's -probably safest to just set it to a little larger than this value. Eg, with a +probably safest to just set it to a little larger than this value. E.g., with a default Exim message size of 50M and a default ClamAV StreamMaxLength of 10M, some problems may result. @@ -14385,7 +15488,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. -.option openssl_options main "string list" unset +.option openssl_options main "string list" "+no_sslv2 +single_dh_use" .cindex "OpenSSL "compatibility options" This option allows an administrator to adjust the SSL options applied by OpenSSL to connections. It is given as a space-separated list of items, @@ -14405,18 +15508,21 @@ yourself in the foot in various unpleasant ways. This option should not be adjusted lightly. An unrecognised item will be detected at startup, by invoking Exim with the &%-bV%& flag. -.new +The option affects Exim operating both as a server and as a client. + Historical note: prior to release 4.80, Exim defaulted this value to "+dont_insert_empty_fragments", which may still be needed for compatibility with some clients, but which lowers security by increasing exposure to some now infamous attacks. -.wen -An example: +Examples: .code # Make both old MS and old Eudora happy: openssl_options = -all +microsoft_big_sslv3_buffer \ +dont_insert_empty_fragments + +# Disable older protocol versions: +openssl_options = +no_sslv2 +no_sslv3 .endd Possible options may include: @@ -14459,6 +15565,8 @@ Possible options may include: .next &`no_tlsv1_2`& .next +&`safari_ecdhe_ecdsa_bug`& +.next &`single_dh_use`& .next &`single_ecdh_use`& @@ -14474,6 +15582,13 @@ Possible options may include: &`tls_rollback_bug`& .endlist +As an aside, the &`safari_ecdhe_ecdsa_bug`& item is a misnomer and affects +all clients connecting using the MacOS SecureTransport TLS facility prior +to MacOS 10.8.4, including email clients. If you see old MacOS clients failing +to negotiate TLS then this option value might help, provided that your OpenSSL +release is new enough to contain this work-around. This may be a situation +where you have to upgrade OpenSSL to get buggy clients working. + .option oracle_servers main "string list" unset .cindex "Oracle" "server list" @@ -14548,6 +15663,15 @@ that clients will use it; &"out of order"& commands that are &"expected"& do not count as protocol errors (see &%smtp_max_synprot_errors%&). +.option prdr_enable main boolean false +.cindex "PRDR" "enabling on server" +This option can be used to enable the Per-Recipient Data Response extension +to SMTP, defined by Eric Hall. +If the option is set, PRDR is advertised by Exim when operating as a server. +If the client requests PRDR, and more than one recipient, for a message +an additional ACL is called for each recipient after the message content +is received. See section &<>&. + .option preserve_message_logs main boolean false .cindex "message logs" "preserving" If this option is set, message log files are not deleted when messages are @@ -14800,7 +15924,7 @@ received_header_text = Received: \ ${if def:sender_helo_name {(helo=$sender_helo_name)\n\t}}}}\ by $primary_hostname \ ${if def:received_protocol {with $received_protocol}} \ - ${if def:tls_cipher {($tls_cipher)\n\t}}\ + ${if def:tls_in_cipher {($tls_in_cipher)\n\t}}\ (Exim $version_number)\n\t\ ${if def:sender_address \ {(envelope-from <$sender_address>)\n\t}}\ @@ -14959,13 +16083,15 @@ the time of delivery. They are normally used only for final local deliveries. This option is an obsolete synonym for &%bounce_return_size_limit%&. -.option rfc1413_hosts main "host list&!!" * +.option rfc1413_hosts main "host list&!!" @[] .cindex "RFC 1413" .cindex "host" "for RFC 1413 calls" -RFC 1413 identification calls are made to any client host which matches an item -in the list. +RFC 1413 identification calls are made to any client host which matches +an item in the list. +The default value specifies just this host, being any local interface +for the system. -.option rfc1413_query_timeout main time 5s +.option rfc1413_query_timeout main time 0s .cindex "RFC 1413" "query timeout" .cindex "timeout" "for RFC 1413 call" This sets the timeout on RFC 1413 identification calls. If it is set to zero, @@ -14983,6 +16109,22 @@ it qualifies them only if the message came from a host that matches &%sender_unqualified_hosts%&, or if the message was submitted locally (not using TCP/IP), and the &%-bnq%& option was not set. +.option set_environment main "string list" empty +.cindex "environment" +This option allows to set individual environment variables that the +currently linked libraries and programs in child processes use. The +default list is empty, + + +.option slow_lookup_log main integer 0 +.cindex "logging" "slow lookups" +.cindex "dns" "logging slow lookups" +This option controls logging of slow lookups. +If the value is nonzero it is taken as a number of milliseconds +and lookups taking longer than this are logged. +Currently this applies only to DNS lookups. + + .option smtp_accept_keepalive main boolean true .cindex "keepalive" "on incoming connection" @@ -15043,8 +16185,15 @@ live with. . Allow this long option name to split; give it unsplit as a fifth argument . for the automatic .oindex that is generated by .option. - -.option "smtp_accept_max_per_ &~&~connection" main integer 1000 &&& +. We insert " &~&~" which is both pretty nasty visually and results in +. non-searchable text. HowItWorks.txt mentions an option for inserting +. zero-width-space, which would be nicer visually and results in (at least) +. html that Firefox will split on when it's forced to reflow (rather than +. inserting a horizontal scrollbar). However, the text is still not +. searchable. NM changed this occurrence for bug 1197 to no longer allow +. the option name to split. + +.option "smtp_accept_max_per_connection" main integer 1000 &&& smtp_accept_max_per_connection .cindex "SMTP" "limiting incoming message count" .cindex "limit" "messages per SMTP connection" @@ -15094,10 +16243,9 @@ also &%queue_only%&, &%queue_only_load%&, &%queue_smtp_domains%&, and the various &%-od%&&'x'& command line options. -. Allow this long option name to split; give it unsplit as a fifth argument -. for the automatic .oindex that is generated by .option. +. See the comment on smtp_accept_max_per_connection -.option "smtp_accept_queue_per_ &~&~connection" main integer 10 &&& +.option "smtp_accept_queue_per_connection" main integer 10 &&& smtp_accept_queue_per_connection .cindex "queueing incoming messages" .cindex "message" "queueing by message count" @@ -15353,7 +16501,7 @@ See &%smtp_ratelimit_hosts%& above. See &%smtp_ratelimit_hosts%& above. -.option smtp_receive_timeout main time 5m +.option smtp_receive_timeout main time&!! 5m .cindex "timeout" "for SMTP input" .cindex "SMTP" "input timeout" This sets a timeout value for SMTP reception. It applies to all forms of SMTP @@ -15368,6 +16516,10 @@ SMTP data timeout on connection from... The former means that Exim was expecting to read an SMTP command; the latter means that it was in the DATA phase, reading the contents of a message. +If the first character of the option is a &"$"& the option is +expanded before use and may depend on +&$sender_host_name$&, &$sender_host_address$& and &$sender_host_port$&. + .oindex "&%-os%&" The value set by this option can be overridden by the @@ -15397,6 +16549,17 @@ example, instead of &"Administrative prohibition"&, it might give: 550 failing address in "From" header is: >& for details of Exim's support for internationalisation. +.wen + + .option spamd_address main string "see below" This option is available when Exim is compiled with the content-scanning extension. It specifies how Exim connects to SpamAssassin's &%spamd%& daemon. @@ -15640,7 +16803,9 @@ runs. This is appropriate behaviour for obtaining wall-clock time on some, but unfortunately not all, operating systems. -.option tls_advertise_hosts main "host list&!!" unset +.new +.option tls_advertise_hosts main "host list&!!" * +.wen .cindex "TLS" "advertising" .cindex "encryption" "on SMTP connection" .cindex "SMTP" "encrypted connection" @@ -15648,6 +16813,11 @@ When Exim is built with support for TLS encrypted connections, the availability of the STARTTLS command to set up an encrypted session is advertised in response to EHLO only to those client hosts that match this option. See chapter &<>& for details of Exim's support for TLS. +.new +Note that the default value requires that a certificate be supplied +using the &%tls_certificate%& option. If no certificate is available then +the &%tls_advertise_hosts%& option should be set empty. +.wen .option tls_certificate main string&!! unset @@ -15663,12 +16833,10 @@ receiving incoming messages as a server. If you want to supply certificates for use when sending messages as a client, you must set the &%tls_certificate%& option in the relevant &(smtp)& transport. -.new -If the option contains &$tls_sni$& and Exim is built against OpenSSL, then +If the option contains &$tls_out_sni$& and Exim is built against OpenSSL, then if the OpenSSL build supports TLS extensions and the TLS client sends the Server Name Indication extension, then this option and others documented in &<>& will be re-expanded. -.wen .option tls_crl main string&!! unset .cindex "TLS" "server certificate revocation list" @@ -15676,12 +16844,9 @@ Server Name Indication extension, then this option and others documented in This option specifies a certificate revocation list. The expanded value must be the name of a file that contains a CRL in PEM format. -.new See &<>& for discussion of when this option might be re-expanded. -.wen -.new .option tls_dh_max_bits main integer 2236 .cindex "TLS" "D-H bit count" The number of bits used for Diffie-Hellman key-exchange may be suggested by @@ -15701,23 +16866,92 @@ number. Note that the value passed to GnuTLS for *generating* a new prime may be a little less than this figure, because GnuTLS is inexact and may produce a larger prime than requested. -.wen .option tls_dhparam main string&!! unset .cindex "TLS" "D-H parameters for server" -The value of this option is expanded, and must then be the absolute path to -a file which contains the server's DH parameter values. -This is used only for OpenSSL. When Exim is linked with GnuTLS, this option is -ignored. See section &<>& for further details. +The value of this option is expanded and indicates the source of DH parameters +to be used by Exim. + +If it is a filename starting with a &`/`&, then it names a file from which DH +parameters should be loaded. If the file exists, it should hold a PEM-encoded +PKCS#3 representation of the DH prime. If the file does not exist, for +OpenSSL it is an error. For GnuTLS, Exim will attempt to create the file and +fill it with a generated DH prime. For OpenSSL, if the DH bit-count from +loading the file is greater than &%tls_dh_max_bits%& then it will be ignored, +and treated as though the &%tls_dhparam%& were set to "none". + +If this option expands to the string "none", then no DH parameters will be +loaded by Exim. + +If this option expands to the string "historic" and Exim is using GnuTLS, then +Exim will attempt to load a file from inside the spool directory. If the file +does not exist, Exim will attempt to create it. +See section &<>& for further details. + +If Exim is using OpenSSL and this option is empty or unset, then Exim will load +a default DH prime; the default is the 2048 bit prime described in section +2.2 of RFC 5114, "2048-bit MODP Group with 224-bit Prime Order Subgroup", which +in IKE is assigned number 23. + +Otherwise, the option must expand to the name used by Exim for any of a number +of DH primes specified in RFC 2409, RFC 3526 and RFC 5114. As names, Exim uses +"ike" followed by the number used by IKE, of "default" which corresponds to +"ike23". + +The available primes are: +&`ike1`&, &`ike2`&, &`ike5`&, +&`ike14`&, &`ike15`&, &`ike16`&, &`ike17`&, &`ike18`&, +&`ike22`&, &`ike23`& (aka &`default`&) and &`ike24`&. + +Some of these will be too small to be accepted by clients. +Some may be too large to be accepted by clients. + +The TLS protocol does not negotiate an acceptable size for this; clients tend +to hard-drop connections if what is offered by the server is unacceptable, +whether too large or too small, and there's no provision for the client to +tell the server what these constraints are. Thus, as a server operator, you +need to make an educated guess as to what is most likely to work for your +userbase. + +Some known size constraints suggest that a bit-size in the range 2048 to 2236 +is most likely to maximise interoperability. The upper bound comes from +applications using the Mozilla Network Security Services (NSS) library, which +used to set its &`DH_MAX_P_BITS`& upper-bound to 2236. This affects many +mail user agents (MUAs). The lower bound comes from Debian installs of Exim4 +prior to the 4.80 release, as Debian used to patch Exim to raise the minimum +acceptable bound from 1024 to 2048. + + +.option tls_eccurve main string&!! prime256v1 +.cindex TLS "EC cryptography" +If built with a recent-enough version of OpenSSL, +this option selects a EC curve for use by Exim. + +Curve names of the form &'prime256v1'& are accepted. +For even more-recent library versions, names of the form &'P-512'& +are also accepted, plus the special value &'auto'& +which tells the library to choose. + +If the option is set to an empty string, no EC curves will be enabled. + + +.option tls_ocsp_file main string&!! unset +.cindex TLS "certificate status" +.cindex TLS "OCSP proof file" +This option +must if set expand to the absolute path to a file which contains a current +status proof for the server's certificate, as obtained from the +Certificate Authority. .new -If the DH bit-count from loading the file is greater than &%tls_dh_max_bits$& -then it will be ignored. +Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later). .wen .option tls_on_connect_ports main "string list" unset +.cindex SSMTP +.cindex SMTPS This option specifies a list of incoming SSMTP (aka SMTPS) ports that should operate the obsolete SSMTP (SMTPS) protocol, where a TLS session is immediately set up without waiting for the client to issue a STARTTLS command. For @@ -15733,9 +16967,7 @@ the expansion is forced to fail, or the result is an empty string, the private key is assumed to be in the same file as the server's certificates. See chapter &<>& for further details. -.new See &<>& for discussion of when this option might be re-expanded. -.wen .option tls_remember_esmtp main boolean false @@ -15766,26 +16998,40 @@ preference order of the available ciphers. Details are given in sections See &%tls_verify_hosts%& below. -.option tls_verify_certificates main string&!! unset +.option tls_verify_certificates main string&!! system .cindex "TLS" "client certificate verification" .cindex "certificate" "verification of client" -The value of this option is expanded, and must then be the absolute path to -a file containing permitted certificates for clients that -match &%tls_verify_hosts%& or &%tls_try_verify_hosts%&. Alternatively, if you -are using OpenSSL, you can set &%tls_verify_certificates%& to the name of a -directory containing certificate files. This does not work with GnuTLS; the -option must be set to the name of a single file if you are using GnuTLS. +The value of this option is expanded, and must then be either the +word "system" +or the absolute path to +a file or directory containing permitted certificates for clients that +match &%tls_verify_hosts%& or &%tls_try_verify_hosts%&. + +The "system" value for the option will use a +system default location compiled into the SSL library. +This is not available for GnuTLS versions preceding 3.0.20, +and will be taken as empty; an explicit location +must be specified. + +The use of a directory for the option value is not available for GnuTLS versions +preceding 3.3.6 and a single file must be used. + +With OpenSSL the certificates specified +explicitly +either by file or directory +are added to those given by the system default location. These certificates should be for the certificate authorities trusted, rather than the public cert of individual clients. With both OpenSSL and GnuTLS, if the value is a file then the certificates are sent by Exim as a server to connecting clients, defining the list of accepted certificate authorities. Thus the values defined should be considered public data. To avoid this, -use OpenSSL with a directory. +use the explicit directory version. -.new See &<>& for discussion of when this option might be re-expanded. -.wen + +A forced expansion failure or setting to an empty string is equivalent to +being unset. .option tls_verify_hosts main "host list&!!" unset @@ -16124,7 +17370,7 @@ router is skipped, and the address is offered to the next one. If the result is any other value, the router is run (as this is the last precondition to be evaluated, all the other preconditions must be true). -This option is unique in that multiple &%condition%& options may be present. +This option is unusual in that multiple &%condition%& options may be present. All &%condition%& options must succeed. The &%condition%& option provides a means of applying custom conditions to the @@ -16149,11 +17395,52 @@ If the expansion fails (other than forced failure) delivery is deferred. Some of the other precondition options are common special cases that could in fact be specified using &%condition%&. +Historical note: We have &%condition%& on ACLs and on Routers. Routers +are far older, and use one set of semantics. ACLs are newer and when +they were created, the ACL &%condition%& process was given far stricter +parse semantics. The &%bool{}%& expansion condition uses the same rules as +ACLs. The &%bool_lax{}%& expansion condition uses the same rules as +Routers. More pointedly, the &%bool_lax{}%& was written to match the existing +Router rules processing behavior. + +This is best illustrated in an example: +.code +# If used in an ACL condition will fail with a syntax error, but +# in a router condition any extra characters are treated as a string + +$ exim -be '${if eq {${lc:GOOGLE.com}} {google.com}} {yes} {no}}' +true {yes} {no}} + +$ exim -be '${if eq {${lc:WHOIS.com}} {google.com}} {yes} {no}}' + {yes} {no}} +.endd +In each example above, the &%if%& statement actually ends after +&"{google.com}}"&. Since no true or false braces were defined, the +default &%if%& behavior is to return a boolean true or a null answer +(which evaluates to false). The rest of the line is then treated as a +string. So the first example resulted in the boolean answer &"true"& +with the string &" {yes} {no}}"& appended to it. The second example +resulted in the null output (indicating false) with the string +&" {yes} {no}}"& appended to it. + +In fact you can put excess forward braces in too. In the router +&%condition%&, Exim's parser only looks for &"{"& symbols when they +mean something, like after a &"$"& or when required as part of a +conditional. But otherwise &"{"& and &"}"& are treated as ordinary +string characters. + +Thus, in a Router, the above expansion strings will both always evaluate +true, as the result of expansion is a non-empty string which doesn't +match an explicit false value. This can be tricky to debug. By +contrast, in an ACL either of those strings will always result in an +expansion error because the result doesn't look sufficiently boolean. + .option debug_print routers string&!! unset .cindex "testing" "variables in drivers" If this option is set and debugging is enabled (see the &%-d%& command line -option), the string is expanded and included in the debugging output. +option) or in address-testing mode (see the &%-bt%& command line option), +the string is expanded and included in the debugging output. If expansion of the string fails, the error message is written to the debugging output, and Exim carries on processing. This option is provided to help with checking out the values of variables and @@ -16162,6 +17449,7 @@ option appears not to be working, &%debug_print%& can be used to output the variables it references. The output happens after checks for &%domains%&, &%local_parts%&, and &%check_local_user%& but before any other preconditions are tested. A newline is added to the text if it does not end with one. +The variable &$router_name$& contains the name of the router. @@ -16171,6 +17459,25 @@ or for any deliveries caused by this router. You should not set this option unless you really, really know what you are doing. See also the generic transport option of the same name. +.option dnssec_request_domains routers "domain list&!!" unset +.cindex "MX record" "security" +.cindex "DNSSEC" "MX lookup" +.cindex "security" "MX lookup" +.cindex "DNS" "DNSSEC" +DNS lookups for domains matching &%dnssec_request_domains%& will be done with +the dnssec request bit set. +This applies to all of the SRV, MX, AAAA, A lookup sequence. + +.option dnssec_require_domains routers "domain list&!!" unset +.cindex "MX record" "security" +.cindex "DNSSEC" "MX lookup" +.cindex "security" "MX lookup" +.cindex "DNS" "DNSSEC" +DNS lookups for domains matching &%dnssec_request_domains%& will be done with +the dnssec request bit set. Any returns not having the Authenticated Data bit +(AD bit) set will be ignored and logged as a host-lookup failure. +This applies to all of the SRV, MX, AAAA, A lookup sequence. + .option domains routers&!? "domain list&!!" unset .cindex "router" "restricting to specific domains" @@ -16188,6 +17495,15 @@ This option must always be set. It specifies which of the available routers is to be used. +.option dsn_lasthop routers boolean false +.cindex "DSN" "success" +.cindex "Delivery Status Notification" "success" +If this option is set true, and extended DSN (RFC3461) processing is in effect, +Exim will not pass on DSN requests to downstream DSN-aware hosts but will +instead send a success DSN as if the next hop does not support DSN. +Not effective on redirect routers. + + .option errors_to routers string&!! unset .cindex "envelope sender" @@ -16306,11 +17622,13 @@ and the discussion in chapter &<>&. -.option headers_add routers string&!! unset +.option headers_add routers list&!! unset .cindex "header lines" "adding" .cindex "router" "adding header lines" -This option specifies a string of text that is expanded at routing time, and -associated with any addresses that are accepted by the router. However, this +This option specifies a list of text headers, +newline-separated (by default, changeable in the usual way), +that is associated with any addresses that are accepted by the router. +Each item is separately expanded, at routing time. However, this option has no effect when an address is just being verified. The way in which the text is used to add header lines at transport time is described in section &<>&. New header lines are not actually added until the @@ -16319,10 +17637,13 @@ header lines in string expansions in the transport's configuration do not &"see"& the added header lines. The &%headers_add%& option is expanded after &%errors_to%&, but before -&%headers_remove%& and &%transport%&. If the expanded string is empty, or if -the expansion is forced to fail, the option has no effect. Other expansion +&%headers_remove%& and &%transport%&. If an item is empty, or if +an item expansion is forced to fail, the item has no effect. Other expansion failures are treated as configuration errors. +Unlike most options, &%headers_add%& can be specified multiple times +for a router; all listed headers are added. + &*Warning 1*&: The &%headers_add%& option cannot be used for a &(redirect)& router that has the &%one_time%& option set. @@ -16339,11 +17660,13 @@ avoided. The &%repeat_use%& option of the &%redirect%& router may be of help. -.option headers_remove routers string&!! unset +.option headers_remove routers list&!! unset .cindex "header lines" "removing" .cindex "router" "removing header lines" -This option specifies a string of text that is expanded at routing time, and -associated with any addresses that are accepted by the router. However, this +This option specifies a list of text headers, +colon-separated (by default, changeable in the usual way), +that is associated with any addresses that are accepted by the router. +Each item is separately expanded, at routing time. However, this option has no effect when an address is just being verified. The way in which the text is used to remove header lines at transport time is described in section &<>&. Header lines are not actually removed until @@ -16352,10 +17675,13 @@ to header lines in string expansions in the transport's configuration still &"see"& the original header lines. The &%headers_remove%& option is expanded after &%errors_to%& and -&%headers_add%&, but before &%transport%&. If the expansion is forced to fail, -the option has no effect. Other expansion failures are treated as configuration +&%headers_add%&, but before &%transport%&. If an item expansion is forced to fail, +the item has no effect. Other expansion failures are treated as configuration errors. +Unlike most options, &%headers_remove%& can be specified multiple times +for a router; all listed headers are removed. + &*Warning 1*&: The &%headers_remove%& option cannot be used for a &(redirect)& router that has the &%one_time%& option set. @@ -16364,6 +17690,11 @@ removal requests are deleted when the address is passed on to subsequent routers, and this can lead to problems with duplicates -- see the similar warning for &%headers_add%& above. +&*Warning 3*&: Because of the separate expansion of the list items, +items that contain a list separator must have it doubled. +To avoid this, change the list separator (&<>&). + + .option ignore_target_hosts routers "host list&!!" unset .cindex "IP address" "discarding" @@ -16992,7 +18323,8 @@ Setting this option has the effect of setting &%verify_sender%& and .cindex "EXPN" "with &%verify_only%&" .oindex "&%-bv%&" .cindex "router" "used only when verifying" -If this option is set, the router is used only when verifying an address or +If this option is set, the router is used only when verifying an address, +delivering in cutthrough mode or testing with the &%-bv%& option, not when actually doing a delivery, testing with the &%-bt%& option, or running the SMTP EXPN command. It can be further restricted to verifying only senders or recipients by means of @@ -17006,10 +18338,12 @@ user or group. .option verify_recipient routers&!? boolean true If this option is false, the router is skipped when verifying recipient -addresses +addresses, +delivering in cutthrough mode or testing recipient verification using &%-bv%&. See section &<>& for a list of the order in which preconditions are evaluated. +See also the &$verify_mode$& variable. .option verify_sender routers&!? boolean true @@ -17017,6 +18351,7 @@ If this option is false, the router is skipped when verifying sender addresses or testing sender verification using &%-bvs%&. See section &<>& for a list of the order in which preconditions are evaluated. +See also the &$verify_mode$& variable. .ecindex IIDgenoprou1 .ecindex IIDgenoprou2 @@ -17091,7 +18426,7 @@ happens is controlled by the generic &%self%& option. .section "Problems with DNS lookups" "SECTprowitdnsloo" There have been problems with DNS servers when SRV records are looked up. -Some mis-behaving servers return a DNS error or timeout when a non-existent +Some misbehaving servers return a DNS error or timeout when a non-existent SRV record is sought. Similar problems have in the past been reported for MX records. The global &%dns_again_means_nonexist%& option can help with this problem, but it is heavy-handed because it is a global option. @@ -17107,13 +18442,15 @@ look for A or AAAA records, unless the domain matches &%mx_domains%&, in which case routing fails. -.new .section "Declining addresses by dnslookup" "SECTdnslookupdecline" .cindex "&(dnslookup)& router" "declines" There are a few cases where a &(dnslookup)& router will decline to accept an address; if such a router is expected to handle "all remaining non-local domains", then it is important to set &%no_more%&. +The router will defer rather than decline if the domain +is found in the &%fail_defer_domains%& router option. + Reasons for a &(dnslookup)& router to decline currently include: .ilist The domain does not exist in DNS @@ -17138,7 +18475,6 @@ The domain is not syntactically valid (see also &%allow_utf8_domains%& and &%check_secondary_mx%& is set on this router but the local host can not be found in the MX records (see below) .endlist -.wen @@ -17193,6 +18529,18 @@ when there is a DNS lookup error. + +.option fail_defer_domains dnslookup "domain list&!!" unset +.cindex "MX record" "not found" +DNS lookups for domains matching &%fail_defer_domains%& +which find no matching record will cause the router to defer +rather than the default behaviour of decline. +This maybe be useful for queueing messages for a newly created +domain while the DNS configuration is not ready. +However, it will result in any message with mistyped domains +also being queued. + + .option mx_domains dnslookup "domain list&!!" unset .cindex "MX record" "required to exist" .cindex "SRV record" "required to exist" @@ -18161,6 +19509,11 @@ However, there are some private options which define transports for delivery to files and pipes, and for generating autoreplies. See the &%file_transport%&, &%pipe_transport%& and &%reply_transport%& descriptions below. +If success DSNs have been requested +.cindex "DSN" "success" +.cindex "Delivery Status Notification" "success" +redirection triggers one and the DSN options are not passed any further. + .section "Redirection data" "SECID124" @@ -18364,6 +19717,16 @@ quote just the command. An item such as .endd is interpreted as a pipe with a rather strange command name, and no arguments. +Note that the above example assumes that the text comes from a lookup source +of some sort, so that the quotes are part of the data. If composing a +redirect router with a &%data%& option directly specifying this command, the +quotes will be used by the configuration parser to define the extent of one +string, but will not be passed down into the redirect router itself. There +are two main approaches to get around this: escape quotes to be part of the +data itself, or avoid using this mechanism and instead create a custom +transport with the &%command%& option set and reference that transport from +an &%accept%& router. + .next .cindex "file" "in redirection list" .cindex "address redirection" "to file" @@ -18417,7 +19780,7 @@ the router to decline. Instead, the alias item .cindex "black hole" .cindex "abandoning mail" &':blackhole:'& can be used. It does what its name implies. No delivery is -done, and no error message is generated. This has the same effect as specifing +done, and no error message is generated. This has the same effect as specifying &_/dev/null_& as a destination, but it can be independently disabled. &*Warning*&: If &':blackhole:'& appears anywhere in a redirection list, no @@ -19304,7 +20667,8 @@ so on when debugging driver configurations. For example, if a &%headers_add%& option is not working properly, &%debug_print%& could be used to output the variables it references. A newline is added to the text if it does not end with one. - +The variables &$transport_name$& and &$router_name$& contain the name of the +transport and the router that called it. .option delivery_date_add transports boolean false .cindex "&'Delivery-date:'& header line" @@ -19332,6 +20696,13 @@ its removal from incoming messages, so that delivered messages can safely be resent to other recipients. +.option event_action transports string&!! unset +.cindex events +This option declares a string to be expanded for Exim's events mechanism. +For details see &<>&. +.wen + + .option group transports string&!! "Exim group" .cindex "transport" "group; specifying" This option specifies a gid for running the transport process, overriding any @@ -19339,16 +20710,20 @@ value that the router supplies, and also overriding any value associated with &%user%& (see below). -.option headers_add transports string&!! unset +.option headers_add transports list&!! unset .cindex "header lines" "adding in transport" .cindex "transport" "header lines; adding" -This option specifies a string of text that is expanded and added to the header +This option specifies a list of text headers, +newline-separated (by default, changeable in the usual way), +which are (separately) expanded and added to the header portion of a message as it is transported, as described in section &<>&. Additional header lines can also be specified by routers. If the result of the expansion is an empty string, or if the expansion is forced to fail, no action is taken. Other expansion failures are treated as errors and cause the delivery to be deferred. +Unlike most options, &%headers_add%& can be specified multiple times +for a transport; all listed headers are added. .option headers_only transports boolean false @@ -19361,16 +20736,26 @@ transports, the settings of &%message_prefix%& and &%message_suffix%& should be checked, since this option does not automatically suppress them. -.option headers_remove transports string&!! unset +.option headers_remove transports list&!! unset .cindex "header lines" "removing" .cindex "transport" "header lines; removing" -This option specifies a string that is expanded into a list of header names; +This option specifies a list of header names, +colon-separated (by default, changeable in the usual way); these headers are omitted from the message as it is transported, as described in section &<>&. Header removal can also be specified by -routers. If the result of the expansion is an empty string, or if the expansion +routers. +Each list item is separately expanded. +If the result of the expansion is an empty string, or if the expansion is forced to fail, no action is taken. Other expansion failures are treated as errors and cause the delivery to be deferred. +Unlike most options, &%headers_remove%& can be specified multiple times +for a router; all listed headers are removed. + +&*Warning*&: Because of the separate expansion of the list items, +items that contain a list separator must have it doubled. +To avoid this, change the list separator (&<>&). + .option headers_rewrite transports string unset @@ -19419,6 +20804,32 @@ transport, the &[initgroups()]& function is called when running the transport to ensure that any additional groups associated with the uid are set up. +.new +.option max_parallel transports integer&!! unset +.cindex limit "transport parallelism" +.cindex transport "parallel processes" +.cindex transport "concurrency limit" +.cindex "delivery" "parallelism for transport" +If this option is set and expands to an integer greater than zero +it limits the number of concurrent runs of the transport. +The control does not apply to shadow transports. + +.cindex "hints database" "transport concurrency control" +Exim implements this control by means of a hints database in which a record is +incremented whenever a transport process is beaing created. The record +is decremented and possibly removed when the process terminates. +Obviously there is scope for +records to get left lying around if there is a system or program crash. To +guard against this, Exim ignores any records that are more than six hours old. + +If you use this option, you should also arrange to delete the +relevant hints database whenever your system reboots. The names of the files +start with &_misc_& and they are kept in the &_spool/db_& directory. There +may be one or two files, depending on the type of DBM in use. The same files +are used for ETRN and smtp transport serialization. +.wen + + .option message_size_limit transports string&!! 0 .cindex "limit" "message size per transport" .cindex "size" "of message, limit" @@ -19565,6 +20976,9 @@ headers that some sites insist on. This option sets up a filtering (in the Unix shell sense) process for messages at transport time. It should not be confused with mail filtering as set up by individual users or via a system filter. +.new +If unset, or expanding to an empty string, no filtering is done. +.wen When the message is about to be written out, the command specified by &%transport_filter%& is started up in a separate, parallel process, and @@ -19675,7 +21089,7 @@ message, which happens if the &%return_message%& option is set. .option transport_filter_timeout transports time 5m .cindex "transport" "filter, timeout" -When Exim is reading the output of a transport filter, it a applies a timeout +When Exim is reading the output of a transport filter, it applies a timeout that can be set by this option. Exceeding the timeout is normally treated as a temporary delivery failure. However, if a transport filter is used with a &(pipe)& transport, a timeout in the transport filter is treated in the same @@ -20259,7 +21673,6 @@ This option applies only to deliveries in maildir format, and is described in section &<>& below. -.new .option maildir_use_size_file appendfile&!! boolean false .cindex "maildir format" "&_maildirsize_& file" The result of string expansion for this option must be a valid boolean value. @@ -20268,7 +21681,6 @@ creates a &_maildirsize_& file in a maildir if one does not exist, taking the quota from the &%quota%& option of the transport. If &%quota%& is unset, the value is zero. See &%maildir_quota_directory_regex%& above and section &<>& below for further details. -.wen .option maildirfolder_create_regex appendfile string unset .cindex "maildir format" "&_maildirfolder_& file" @@ -21293,10 +22705,10 @@ that are routed to the transport. .vindex "&$address_pipe$&" A router redirects an address directly to a pipe command (for example, from an alias or forward file). In this case, &$address_pipe$& contains the text of the -pipe command, and the &%command%& option on the transport is ignored. If only -one address is being transported (&%batch_max%& is not greater than one, or -only one address was redirected to this pipe command), &$local_part$& contains -the local part that was redirected. +pipe command, and the &%command%& option on the transport is ignored unless +&%force_command%& is set. If only one address is being transported +(&%batch_max%& is not greater than one, or only one address was redirected to +this pipe command), &$local_part$& contains the local part that was redirected. .endlist @@ -21318,6 +22730,10 @@ If two messages arrive at almost the same time, and both are routed to a pipe delivery, the two pipe transports may be run concurrently. You must ensure that any pipe commands you set up are robust against this happening. If the commands write to a file, the &%exim_lock%& utility might be of use. +.new +Alternatively the &%max_parallel%& option could be used with a value +of "1" to enforce serialization. +.wen @@ -21404,6 +22820,15 @@ inserted in the argument list at that point &'as a separate argument'&. This avoids any problems with spaces or shell metacharacters, and is of use when a &(pipe)& transport is handling groups of addresses in a batch. +If &%force_command%& is enabled on the transport, Special handling takes place +for an argument that consists of precisely the text &`$address_pipe`&. It +is handled similarly to &$pipe_addresses$& above. It is expanded and each +argument is inserted in the argument list at that point +&'as a separate argument'&. The &`$address_pipe`& item does not need to be +the only item in the argument; in fact, if it were then &%force_command%& +should behave as a no-op. Rather, it should be used to adjust the command +run while preserving the argument vector separation. + After splitting up into arguments and expansion, the resulting command is run in a subprocess directly from the transport, &'not'& under a shell. The message that is being delivered is supplied on the standard input, and the @@ -21556,6 +22981,24 @@ a bounce message is sent. If &%freeze_signal%& is set, the message will be frozen in Exim's queue instead. +.option force_command pipe boolean false +.cindex "force command" +.cindex "&(pipe)& transport", "force command" +Normally when a router redirects an address directly to a pipe command +the &%command%& option on the transport is ignored. If &%force_command%& +is set, the &%command%& option will used. This is especially +useful for forcing a wrapper or additional argument to be added to the +command. For example: +.code +command = /usr/bin/remote_exec myhost -- $address_pipe +force_command +.endd + +Note that &$address_pipe$& is handled specially in &%command%& when +&%force_command%& is set, expanding out to the original argument vector as +separate items, similarly to a Unix shell &`"$@"`& construct. + + .option ignore_status pipe boolean false If this option is true, the status returned by the subprocess that is set up to run the command is ignored, and Exim behaves as if zero had been returned. @@ -21566,27 +23009,29 @@ from the transport unless the status value is one of those listed in &*Note*&: This option does not apply to timeouts, which do not return a status. See the &%timeout_defer%& option for how timeouts are handled. + .option log_defer_output pipe boolean false .cindex "&(pipe)& transport" "logging output" If this option is set, and the status returned by the command is one of the codes listed in &%temp_errors%& (that is, delivery was deferred), -and any output was produced, the first line of it is written to the main log. +and any output was produced on stdout or stderr, the first line of it is +written to the main log. .option log_fail_output pipe boolean false -If this option is set, and the command returns any output, and also ends with a -return code that is neither zero nor one of the return codes listed in -&%temp_errors%& (that is, the delivery failed), the first line of output is -written to the main log. This option and &%log_output%& are mutually exclusive. -Only one of them may be set. - +If this option is set, and the command returns any output on stdout or +stderr, and also ends with a return code that is neither zero nor one of +the return codes listed in &%temp_errors%& (that is, the delivery +failed), the first line of output is written to the main log. This +option and &%log_output%& are mutually exclusive. Only one of them may +be set. .option log_output pipe boolean false -If this option is set and the command returns any output, the first line of -output is written to the main log, whatever the return code. This option and -&%log_fail_output%& are mutually exclusive. Only one of them may be set. - +If this option is set and the command returns any output on stdout or +stderr, the first line of output is written to the main log, whatever +the return code. This option and &%log_fail_output%& are mutually +exclusive. Only one of them may be set. .option max_output pipe integer 20K @@ -21917,6 +23362,9 @@ appropriate values for the outgoing connection, and these are the values that are in force when any authenticators are run and when the &%authenticated_sender%& option is expanded. +These variables are deprecated in favour of &$tls_in_cipher$& et. al. +and will be removed in a future release. + .section "Private options for smtp" "SECID146" .cindex "options" "&(smtp)& transport" @@ -21954,7 +23402,7 @@ ignored. The expansion happens after the outgoing connection has been made and TLS started, if required. This means that the &$host$&, &$host_address$&, -&$tls_cipher$&, and &$tls_peerdn$& variables are set according to the +&$tls_out_cipher$&, and &$tls_out_peerdn$& variables are set according to the particular connection. If the SMTP session is not authenticated, the expansion of @@ -22013,6 +23461,15 @@ the message. As a result, the overall timeout for a message depends on the size of the message. Its value must not be zero. See also &%final_timeout%&. +.option dkim_domain smtp string&!! unset +.option dkim_selector smtp string&!! unset +.option dkim_private_key smtp string&!! unset +.option dkim_canon smtp string&!! unset +.option dkim_strict smtp string&!! unset +.option dkim_sign_headers smtp string&!! unset +DKIM signing options. For details see &<>&. + + .option delay_after_cutoff smtp boolean true This option controls what happens when all remote IP addresses for a given domain have been inaccessible for so long that they have passed their retry @@ -22050,6 +23507,43 @@ See the &%search_parents%& option in chapter &<>& for more details. +.option dnssec_request_domains smtp "domain list&!!" unset +.cindex "MX record" "security" +.cindex "DNSSEC" "MX lookup" +.cindex "security" "MX lookup" +.cindex "DNS" "DNSSEC" +DNS lookups for domains matching &%dnssec_request_domains%& will be done with +the dnssec request bit set. +This applies to all of the SRV, MX, AAAA, A lookup sequence. + + + +.option dnssec_require_domains smtp "domain list&!!" unset +.cindex "MX record" "security" +.cindex "DNSSEC" "MX lookup" +.cindex "security" "MX lookup" +.cindex "DNS" "DNSSEC" +DNS lookups for domains matching &%dnssec_request_domains%& will be done with +the dnssec request bit set. Any returns not having the Authenticated Data bit +(AD bit) set will be ignored and logged as a host-lookup failure. +This applies to all of the SRV, MX, AAAA, A lookup sequence. + + + +.option dscp smtp string&!! unset +.cindex "DCSP" "outbound" +This option causes the DSCP value associated with a socket to be set to one +of a number of fixed strings or to numeric value. +The &%-bI:dscp%& option may be used to ask Exim which names it knows of. +Common values include &`throughput`&, &`mincost`&, and on newer systems +&`ef`&, &`af41`&, etc. Numeric values may be in the range 0 to 0x3F. + +The outbound packets from Exim will be marked with this value in the header +(for IPv4, the TOS field; for IPv6, the TCLASS field); there is no guarantee +that these values will have any effect, not be stripped by networking +equipment, or do much of anything without cooperation with your Network +Engineer and those of all network operators between the source and destination. + .option fallback_hosts smtp "string list" unset .cindex "fallback" "hosts specified on transport" @@ -22183,6 +23677,12 @@ that matches this list, even if the server host advertises PIPELINING support. Exim will not try to start a TLS session when delivering to any host that matches this list. See chapter &<>& for details of TLS. +.option hosts_verify_avoid_tls smtp "host list&!!" unset +.cindex "TLS" "avoiding for certain hosts" +Exim will not try to start a TLS session for a verify callout, +or when delivering in cutthrough mode, +to any host that matches this list. + .option hosts_max_try smtp integer 5 .cindex "host" "maximum number to try" @@ -22251,6 +23751,18 @@ hard failure if required. See also &%hosts_try_auth%&, and chapter &<>& for details of authentication. +.option hosts_request_ocsp smtp "host list&!!" * +.cindex "TLS" "requiring for certain servers" +Exim will request a Certificate Status on a +TLS session for any host that matches this list. +&%tls_verify_certificates%& should also be set for the transport. + +.option hosts_require_ocsp smtp "host list&!!" unset +.cindex "TLS" "requiring for certain servers" +Exim will request, and check for a valid Certificate Status being given, on a +TLS session for any host that matches this list. +&%tls_verify_certificates%& should also be set for the transport. + .option hosts_require_tls smtp "host list&!!" unset .cindex "TLS" "requiring for certain servers" Exim will insist on using a TLS session when delivering to any host that @@ -22266,6 +23778,13 @@ connects. If authentication fails, Exim will try to transfer the message unauthenticated. See also &%hosts_require_auth%&, and chapter &<>& for details of authentication. +.option hosts_try_prdr smtp "host list&!!" * +.cindex "PRDR" "enabling, optional in client" +This option provides a list of servers to which, provided they announce +PRDR support, Exim will attempt to negotiate PRDR +for multi-recipient messages. +The option can usually be left as default. + .option interface smtp "string list&!!" unset .cindex "bind IP address" .cindex "IP address" "binding" @@ -22322,7 +23841,7 @@ so can cause parallel connections to the same host if &%remote_max_parallel%& permits this. -.option multi_domain smtp boolean true +.option multi_domain smtp boolean&!! true .vindex "&$domain$&" When this option is set, the &(smtp)& transport can handle a number of addresses containing a mixture of different domains provided they all resolve @@ -22331,6 +23850,9 @@ handling only one domain at a time. This is useful if you want to use &$domain$& in an expansion for the transport, because it is set only when there is a single domain involved in a remote delivery. +It is expanded per-address and can depend on any of +&$address_data$&, &$domain_data$&, &$local_part_data$&, +&$host$&, &$host_address$& and &$host_port$&. .option port smtp string&!! "see below" .cindex "port" "sending TCP/IP" @@ -22360,15 +23882,13 @@ protocol (RFC 2033) instead of SMTP. This protocol is sometimes used for local deliveries into closed message stores. Exim also has support for running LMTP over a pipe to a local process &-- see chapter &<>&. -.new -If this option is set to &"smtps"&, the default vaule for the &%port%& option +If this option is set to &"smtps"&, the default value for the &%port%& option changes to &"smtps"&, and the transport initiates TLS immediately after connecting, as an outbound SSL-on-connect, instead of using STARTTLS to upgrade. The Internet standards bodies strongly discourage use of this mode. -.wen -.option retry_include_ip_address smtp boolean true +.option retry_include_ip_address smtp boolean&!! true Exim normally includes both the host name and the IP address in the key it constructs for indexing retry data after a temporary delivery failure. This means that when one of several IP addresses for a host is failing, it gets @@ -22378,9 +23898,8 @@ addresses is not affected. However, in some dialup environments hosts are assigned a different IP address each time they connect. In this situation the use of the IP address as part of the retry key leads to undesirable behaviour. Setting this option false causes -Exim to use only the host name. This should normally be done on a separate -instance of the &(smtp)& transport, set up specially to handle the dialup -hosts. +Exim to use only the host name. +Since it is expanded it can be made to depend on the host or domain. .option serialize_hosts smtp "host list&!!" unset @@ -22406,6 +23925,10 @@ start with &_misc_& and they are kept in the &_spool/db_& directory. There may be one or two files, depending on the type of DBM in use. The same files are used for ETRN serialization. +.new +See also the &%max_parallel%& generic transport option. +.wen + .option size_addition smtp integer 1024 .cindex "SMTP" "SIZE" @@ -22424,6 +23947,14 @@ Alternatively, if the value of &%size_addition%& is set negative, it disables the use of the SIZE option altogether. +.new +.option socks_proxy smtp string&!! unset +.cindex proxy SOCKS +This option enables use of SOCKS proxies for connections made by the +transport. For details see &<>&. +.wen + + .option tls_certificate smtp string&!! unset .cindex "TLS" "client certificate, location of" .cindex "certificate" "client, location of" @@ -22449,6 +23980,17 @@ This option specifies a certificate revocation list. The expanded value must be the name of a file that contains a CRL in PEM format. +.option tls_dh_min_bits smtp integer 1024 +.cindex "TLS" "Diffie-Hellman minimum acceptable size" +When establishing a TLS session, if a ciphersuite which uses Diffie-Hellman +key agreement is negotiated, the server will provide a large prime number +for use. This option establishes the minimum acceptable size of that number. +If the parameter offered by the server is too small, then the TLS handshake +will fail. + +Only supported when using GnuTLS. + + .option tls_privatekey smtp string&!! unset .cindex "TLS" "client private key, location of" .vindex "&$host$&" @@ -22478,19 +24020,19 @@ ciphers is a preference order. -.new .option tls_sni smtp string&!! unset .cindex "TLS" "Server Name Indication" .vindex "&$tls_sni$&" -If this option is set then it sets the $tls_sni variable and causes any +If this option is set then it sets the $tls_out_sni variable and causes any TLS session to pass this value as the Server Name Indication extension to the remote side, which can be used by the remote side to select an appropriate certificate and private key for the session. See &<>& for more information. -OpenSSL only, also requiring a build of OpenSSL that supports TLS extensions. -.wen +Note that for OpenSSL, this feature requires a build of OpenSSL that supports +TLS extensions. + @@ -22507,20 +24049,75 @@ unknown state), opens a new one to the same host, and then tries the delivery in clear. -.option tls_verify_certificates smtp string&!! unset +.option tls_try_verify_hosts smtp "host list&!!" * +.cindex "TLS" "server certificate verification" +.cindex "certificate" "verification of server" +This option gives a list of hosts for which, on encrypted connections, +certificate verification will be tried but need not succeed. +The &%tls_verify_certificates%& option must also be set. +Note that unless the host is in this list +TLS connections will be denied to hosts using self-signed certificates +when &%tls_verify_certificates%& is matched. +The &$tls_out_certificate_verified$& variable is set when +certificate verification succeeds. + + +.option tls_verify_cert_hostnames smtp "host list&!!" * +.cindex "TLS" "server certificate hostname verification" +.cindex "certificate" "verification of server" +This option give a list of hosts for which, +while verifying the server certificate, +checks will be included on the host name +(note that this will generally be the result of a DNS MX lookup) +versus Subject and Subject-Alternate-Name fields. Wildcard names are permitted +limited to being the initial component of a 3-or-more component FQDN. + +There is no equivalent checking on client certificates. + + +.option tls_verify_certificates smtp string&!! system .cindex "TLS" "server certificate verification" .cindex "certificate" "verification of server" .vindex "&$host$&" .vindex "&$host_address$&" -The value of this option must be the absolute path to a file containing -permitted server certificates, for use when setting up an encrypted connection. -Alternatively, if you are using OpenSSL, you can set -&%tls_verify_certificates%& to the name of a directory containing certificate -files. This does not work with GnuTLS; the option must be set to the name of a -single file if you are using GnuTLS. The values of &$host$& and +The value of this option must be either the +word "system" +or the absolute path to +a file or directory containing permitted certificates for servers, +for use when setting up an encrypted connection. + +The "system" value for the option will use a location compiled into the SSL library. +This is not available for GnuTLS versions preceding 3.0.20; a value of "system" +is taken as empty and an explicit location +must be specified. + +The use of a directory for the option value is not available for GnuTLS versions +preceding 3.3.6 and a single file must be used. + +With OpenSSL the certificates specified +explicitly +either by file or directory +are added to those given by the system default location. + +The values of &$host$& and &$host_address$& are set to the name and address of the server during the expansion of this option. See chapter &<>& for details of TLS. +For back-compatibility, +if neither tls_verify_hosts nor tls_try_verify_hosts are set +(a single-colon empty list counts as being set) +and certificate verification fails the TLS connection is closed. + + +.option tls_verify_hosts smtp "host list&!!" unset +.cindex "TLS" "server certificate verification" +.cindex "certificate" "verification of server" +This option gives a list of hosts for which, on encrypted connections, +certificate verification must succeed. +The &%tls_verify_certificates%& option must also be set. +If both this option and &%tls_try_verify_hosts%& are unset +operation is as if this option selected all hosts. + @@ -22991,7 +24588,7 @@ replaced, not just the working part. The replacement must be a complete RFC 2822 address, including the angle brackets if necessary. If text outside angle brackets contains a character whose value is greater than 126 or less than 32 (except for tab), the text is encoded according to RFC 2047. The character set -is taken from &%headers_charset%&, which defaults to ISO-8859-1. +is taken from &%headers_charset%&, which gets its default at build time. When the &"w"& flag is set on a rule that causes an envelope address to be rewritten, all but the working part of the replacement address is discarded. @@ -23147,7 +24744,7 @@ In practice, almost all rules start with a domain name pattern without a local part. .cindex "regular expressions" "in retry rules" -&*Warning*&: If you use a regular expression in a routing rule pattern, it +&*Warning*&: If you use a regular expression in a retry rule pattern, it must match a complete address, not just a domain, because that is how regular expressions work in address lists. .display @@ -23263,6 +24860,13 @@ A server unexpectedly closed the SMTP connection. There may, of course, legitimate reasons for this (host died, network died), but if it repeats a lot for the same host, it indicates something odd. +.vitem &%lookup%& +A DNS lookup for a host failed. +Note that a &%dnslookup%& router will need to have matched +its &%fail_defer_domains%& option for this retry type to be usable. +Also note that a &%manualroute%& router will probably need +its &%host_find_failed%& option set to &%defer%&. + .vitem &%refused_MX%& A connection to a host obtained from an MX record was refused. @@ -23669,18 +25273,16 @@ included by setting .code AUTH_CRAM_MD5=yes AUTH_CYRUS_SASL=yes -.new AUTH_DOVECOT=yes AUTH_GSASL=yes AUTH_HEIMDAL_GSSAPI=yes -.wen AUTH_PLAINTEXT=yes AUTH_SPA=yes +AUTH_TLS=yes .endd in &_Local/Makefile_&, respectively. The first of these supports the CRAM-MD5 authentication mechanism (RFC 2195), and the second provides an interface to the Cyrus SASL authentication library. -.new The third is an interface to Dovecot's authentication system, delegating the work via a socket interface. The fourth provides an interface to the GNU SASL authentication library, which @@ -23691,7 +25293,8 @@ The sixth can be configured to support the PLAIN authentication mechanism (RFC 2595) or the LOGIN mechanism, which is not formally documented, but used by several MUAs. The seventh authenticator supports Microsoft's &'Secure Password Authentication'& mechanism. -.wen +The eighth is an Exim authenticator but not an SMTP one; +instead it can use information from a TLS negotiation. The authenticators are configured using the same syntax as other drivers (see section &<>&). If no authenticators are required, no @@ -23723,7 +25326,6 @@ The remainder of this chapter covers the generic options for the authenticators, followed by general discussion of the way authentication works in Exim. -.new &*Beware:*& the meaning of &$auth1$&, &$auth2$&, ... varies on a per-driver and per-mechanism basis. Please read carefully to determine which variables hold account labels such as usercodes and which hold passwords or other @@ -23745,7 +25347,6 @@ A &'realm'& is a text string, typically a domain name, presented by a server to a client to help it select an account and credentials to use. In some mechanisms, the client and server provably agree on the realm, but clients typically can not treat the realm as secure data to be blindly trusted. -.wen @@ -23759,11 +25360,14 @@ When Exim is authenticating as a client, it skips any authenticator whose used, for example, to skip plain text authenticators when the connection is not encrypted by a setting such as: .code -client_condition = ${if !eq{$tls_cipher}{}} +client_condition = ${if !eq{$tls_out_cipher}{}} .endd -(Older documentation incorrectly states that &$tls_cipher$& contains the cipher -used for incoming messages. In fact, during SMTP delivery, it contains the -cipher used for the delivery.) + + +.option client_set_id authenticators string&!! unset +When client authentication succeeds, this condition is expanded; the +result is used in the log lines for outbound messages. +Typically it will be the user name used for authentication. .option driver authenticators string unset @@ -23793,10 +25397,8 @@ This option must be set for a &%plaintext%& server authenticator, where it is used directly to control authentication. See section &<>& for details. -.new For the &(gsasl)& authenticator, this option is required for various mechanisms; see chapter &<>& for details. -.wen For the other authenticators, &%server_condition%& can be used as an additional authentication or authorization mechanism that is applied after the other @@ -23925,10 +25527,10 @@ authentication mechanisms. For example, it can be used to restrict the advertisement of a particular mechanism to encrypted connections, by a setting such as: .code -server_advertise_condition = ${if eq{$tls_cipher}{}{no}{yes}} +server_advertise_condition = ${if eq{$tls_in_cipher}{}{no}{yes}} .endd -.vindex "&$tls_cipher$&" -If the session is encrypted, &$tls_cipher$& is not empty, and so the expansion +.vindex "&$tls_in_cipher$&" +If the session is encrypted, &$tls_in_cipher$& is not empty, and so the expansion yields &"yes"&, which allows the advertisement to happen. When an Exim server receives an AUTH command from a client, it rejects it @@ -24135,7 +25737,7 @@ to be returned. If the result of a successful expansion is an empty string, expansion is &"1"&, &"yes"&, or &"true"&, authentication succeeds and the generic &%server_set_id%& option is expanded and saved in &$authenticated_id$&. For any other result, a temporary error code is returned, with the expanded -string as the error text. +string as the error text &*Warning*&: If you use a lookup in the expansion to find the user's password, be sure to make the authentication fail if the user is unknown. @@ -24403,7 +26005,6 @@ lookup_cram: Note that this expansion explicitly forces failure if the lookup fails because &$auth1$& contains an unknown user name. -.new As another example, if you wish to re-use a Cyrus SASL sasldb2 file without using the relevant libraries, you need to know the realm to specify in the lookup and then ask for the &"userPassword"& attribute for that user in that @@ -24413,10 +26014,9 @@ cyrusless_crammd5: driver = cram_md5 public_name = CRAM-MD5 server_secret = ${lookup{$auth1:mail.example.org:userPassword}\ - dbmjz{/etc/sasldb2}} + dbmjz{/etc/sasldb2}{$value}fail} server_set_id = $auth1 .endd -.wen .section "Using cram_md5 as a client" "SECID177" .cindex "options" "&(cram_md5)& authenticator (client)" @@ -24491,7 +26091,7 @@ Kerberos, note that because of limitations in the GSSAPI interface, changing the server keytab might need to be communicated down to the Kerberos layer independently. The mechanism for doing so is dependent upon the Kerberos implementation. -.new + For example, for older releases of Heimdal, the environment variable KRB5_KTNAME may be set to point to an alternative keytab file. Exim will pass this variable through from its own inherited environment when started as root or the @@ -24500,7 +26100,6 @@ With newer releases of Heimdal, a setuid Exim may cause Heimdal to discard the environment variable. In practice, for those releases, the Cyrus authenticator is not a suitable interface for GSSAPI (Kerberos) support. Instead, consider the &(heimdal_gssapi)& authenticator, described in chapter &<>& -.wen .section "Using cyrus_sasl as a server" "SECID178" @@ -24531,10 +26130,8 @@ sasl: server_set_id = $auth1 .endd -.new .option server_realm cyrus_sasl string&!! unset This specifies the SASL realm that the server claims to be in. -.wen .option server_service cyrus_sasl string &`smtp`& @@ -24572,6 +26169,7 @@ but it is present in many binary distributions. .scindex IIDdcotauth2 "authenticators" "&(dovecot)&" This authenticator is an interface to the authentication facility of the Dovecot POP/IMAP server, which can support a number of authentication methods. +Note that Dovecot must be configured to use auth-client not auth-userdb. If you are using Dovecot to authenticate POP/IMAP clients, it might be helpful to use the same mechanisms for SMTP authentication. This is a server authenticator only. There is only one option: @@ -24587,7 +26185,7 @@ dovecot_plain: driver = dovecot public_name = PLAIN server_socket = /var/run/dovecot/auth-client - server_set_id = $auth2 + server_set_id = $auth1 dovecot_ntlm: driver = dovecot @@ -24607,7 +26205,6 @@ who authenticated is placed in &$auth1$&. . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.new .chapter "The gsasl authenticator" "CHAPgsasl" .scindex IIDgsaslauth1 "&(gsasl)& authenticator" .scindex IIDgsaslauth2 "authenticators" "&(gsasl)&" @@ -24762,12 +26359,10 @@ gsasl_cyrusless_crammd5: server_condition = yes .endd -.wen . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.new .chapter "The heimdal_gssapi authenticator" "CHAPheimdalgss" .scindex IIDheimdalgssauth1 "&(heimdal_gssapi)& authenticator" .scindex IIDheimdalgssauth2 "authenticators" "&(heimdal_gssapi)&" @@ -24789,7 +26384,7 @@ The value should be a pathname, with no &"file:"& prefix. .option server_service heimdal_gssapi string&!! "smtp" This option specifies the service identifier used, in conjunction with -&%server_hostname%&, for building the identifer for finding credentials +&%server_hostname%&, for building the identifier for finding credentials from the keytab. @@ -24814,7 +26409,6 @@ authentication. If that was empty, this will also be set to the GSS Display Name. .endlist -.wen . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -24907,6 +26501,97 @@ msn: +. //////////////////////////////////////////////////////////////////////////// +. //////////////////////////////////////////////////////////////////////////// + +.chapter "The tls authenticator" "CHAPtlsauth" +.scindex IIDtlsauth1 "&(tls)& authenticator" +.scindex IIDtlsauth2 "authenticators" "&(tls)&" +.cindex "authentication" "Client Certificate" +.cindex "authentication" "X509" +.cindex "Certificate-based authentication" +The &(tls)& authenticator provides server support for +authentication based on client certificates. + +It is not an SMTP authentication mechanism and is not +advertised by the server as part of the SMTP EHLO response. +It is an Exim authenticator in the sense that it affects +the protocol element of the log line, can be tested for +by the &%authenticated%& ACL condition, and can set +the &$authenticated_id$& variable. + +The client must present a verifiable certificate, +for which it must have been requested via the +&%tls_verify_hosts%& or &%tls_try_verify_hosts%& main options +(see &<>&). + +If an authenticator of this type is configured it is +run before any SMTP-level communication is done, +and can authenticate the connection. +If it does, SMTP authentication is not offered. + +A maximum of one authenticator of this type may be present. + + +.cindex "options" "&(tls)& authenticator (server)" +The &(tls)& authenticator has three server options: + +.option server_param1 tls string&!! unset +.cindex "variables (&$auth1$& &$auth2$& etc)" "in &(tls)& authenticator" +This option is expanded after the TLS negotiation and +the result is placed in &$auth1$&. +If the expansion is forced to fail, authentication fails. Any other expansion +failure causes a temporary error code to be returned. + +.option server_param2 tls string&!! unset +.option server_param3 tls string&!! unset +As above, for &$auth2$& and &$auth3$&. + +&%server_param1%& may also be spelled &%server_param%&. + + +Example: +.code +tls: + driver = tls + server_param1 = ${certextract {subj_altname,mail,>:} \ + {$tls_in_peercert}} + server_condition = ${if forany {$auth1} \ + {!= {0} \ + {${lookup ldap{ldap:///\ + mailname=${quote_ldap_dn:${lc:$item}},\ + ou=users,LDAP_DC?mailid} {$value}{0} \ + } } } } + server_set_id = ${if = {1}{${listcount:$auth1}} {$auth1}{}} +.endd +This accepts a client certificate that is verifiable against any +of your configured trust-anchors +which usually means the full set of public CAs) +and which has a SAN with a good account name. +Note that the client cert is on the wire in-clear, including the SAN, +whereas a plaintext SMTP AUTH done inside TLS is not. + +. An alternative might use +. .code +. server_param1 = ${sha256:$tls_in_peercert} +. .endd +. to require one of a set of specific certs that define a given account +. (the verification is still required, but mostly irrelevant). +. This would help for per-device use. +. +. However, for the future we really need support for checking a +. user cert in LDAP - which probably wants a base-64 DER. + +.ecindex IIDtlsauth1 +.ecindex IIDtlsauth2 + + +Note that because authentication is traditionally an SMTP operation, +the &%authenticated%& ACL condition cannot be used in +a connect- or helo-ACL. + + + . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -24997,21 +26682,18 @@ include files and libraries for GnuTLS can be found. There are some differences in usage when using GnuTLS instead of OpenSSL: .ilist -The &%tls_verify_certificates%& option must contain the name of a file, not the -name of a directory (for OpenSSL it can be either). +The &%tls_verify_certificates%& option +cannot be the path of a directory +for GnuTLS versions before 3.3.6 +(for later versions, or OpenSSL, it can be either). .next -The &%tls_dhparam%& option is ignored, because early versions of GnuTLS had no -facility for varying its Diffie-Hellman parameters. -.new -Since then, the GnuTLS support has been updated to generate parameters upon -demand, keeping them in the spool directory. See &<>& for -details. -.wen +The default value for &%tls_dhparam%& differs for historical reasons. .next -.vindex "&$tls_peerdn$&" +.vindex "&$tls_in_peerdn$&" +.vindex "&$tls_out_peerdn$&" Distinguished Name (DN) strings reported by the OpenSSL library use a slash for separating fields; GnuTLS uses commas, in accordance with RFC 2253. This -affects the value of the &$tls_peerdn$& variable. +affects the value of the &$tls_in_peerdn$& and &$tls_out_peerdn$& variables. .next OpenSSL identifies cipher suites using hyphens as separators, for example: DES-CBC3-SHA. GnuTLS historically used underscores, for example: @@ -25024,18 +26706,26 @@ option). .next The &%tls_require_ciphers%& options operate differently, as described in the sections &<>& and &<>&. -.new +.next +The &%tls_dh_min_bits%& SMTP transport option is only honoured by GnuTLS. +When using OpenSSL, this option is ignored. +(If an API is found to let OpenSSL be configured in this way, +let the Exim Maintainers know and we'll likely use it). .next Some other recently added features may only be available in one or the other. This should be documented with the feature. If the documentation does not explicitly state that the feature is infeasible in the other TLS implementation, then patches are welcome. -.wen .endlist .section "GnuTLS parameter computation" "SECTgnutlsparam" -.new +This section only applies if &%tls_dhparam%& is set to &`historic`& or to +an explicit path; if the latter, then the text about generation still applies, +but not the chosen filename. +By default, as of Exim 4.80 a hard-coded D-H prime is used. +See the documentation of &%tls_dhparam%& for more information. + GnuTLS uses D-H parameters that may take a substantial amount of time to compute. It is unreasonable to re-compute them for every TLS session. Therefore, Exim keeps this data in a file in its spool directory, called @@ -25051,6 +26741,10 @@ place, new Exim processes immediately start using it. For maximum security, the parameters that are stored in this file should be recalculated periodically, the frequency depending on your paranoia level. +If you are avoiding using the fixed D-H primes published in RFCs, then you +are concerned about some advanced attacks and will wish to do this; if you do +not regenerate then you might as well stick to the standard primes. + Arranging this is easy in principle; just delete the file when you want new values to be computed. However, there may be a problem. The calculation of new parameters needs random numbers, and these are obtained from &_/dev/random_&. @@ -25106,7 +26800,6 @@ increase the chance of the generated prime actually being within acceptable bounds, as GnuTLS has been observed to overshoot. Note the check step in the procedure above. There is no sane procedure available to Exim to double-check the size of the generated prime, so it might still be too large. -.wen .section "Requiring specific ciphers in OpenSSL" "SECTreqciphssl" @@ -25156,7 +26849,6 @@ includes any ciphers already present they will be ignored: that is, they will not be moved to the end of the list. .endlist -.new The OpenSSL &'ciphers(1)'& command may be used to test the results of a given string: .code @@ -25174,11 +26866,9 @@ tls_require_ciphers = ${if =={$received_port}{25}\ {DEFAULT}\ {HIGH:!MD5:!SHA1}} .endd -.wen -.new .section "Requiring specific ciphers or other parameters in GnuTLS" &&& "SECTreqciphgnu" .cindex "GnuTLS" "specifying parameters for" @@ -25192,7 +26882,8 @@ The GnuTLS library allows the caller to provide a "priority string", documented as part of the &[gnutls_priority_init]& function. This is very similar to the ciphersuite specification in OpenSSL. -The &%tls_require_ciphers%& option is treated as the GnuTLS priority string. +The &%tls_require_ciphers%& option is treated as the GnuTLS priority string +and controls both protocols and ciphers. The &%tls_require_ciphers%& option is available both as an global option, controlling how Exim behaves as a server, and also as an option of the @@ -25203,12 +26894,18 @@ aware of future feature enhancements of GnuTLS. Documentation of the strings accepted may be found in the GnuTLS manual, under "Priority strings". This is online as -&url(http://www.gnu.org/software/gnutls/manual/html_node/Priority-Strings.html), +&url(http://www.gnutls.org/manual/html_node/Priority-Strings.html), but beware that this relates to GnuTLS 3, which may be newer than the version installed on your system. If you are using GnuTLS 3, -&url(http://www.gnu.org/software/gnutls/manual/html_node/Listing-the-ciphersuites-in-a-priority-string.html, then the example code) +&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string, then the example code) on that site can be used to test a given string. +For example: +.code +# Disable older versions of protocols +tls_require_ciphers = NORMAL:%LATEST_RECORD_VERSION:-VERS-SSL3.0 +.endd + Prior to Exim 4.80, an older API of GnuTLS was used, and Exim supported three additional options, "&%gnutls_require_kx%&", "&%gnutls_require_mac%&" and "&%gnutls_require_protocols%&". &%tls_require_ciphers%& was an Exim list. @@ -25224,7 +26921,6 @@ tls_require_ciphers = ${if =={$received_port}{25}\ {NORMAL:%COMPAT}\ {SECURE128}} .endd -.wen .section "Configuring an Exim server to use TLS" "SECID182" @@ -25260,8 +26956,11 @@ tls_privatekey = /some/file/name These options are, in fact, expanded strings, so you can make them depend on the identity of the client that is connected if you wish. The first file contains the server's X509 certificate, and the second contains the private key -that goes with it. These files need to be readable by the Exim user, and must -always be given as full path names. They can be the same file if both the +that goes with it. These files need to be +PEM format and readable by the Exim user, and must +always be given as full path names. +The key must not be password-protected. +They can be the same file if both the certificate and the key are contained within it. If &%tls_privatekey%& is not set, or if its expansion is forced to fail or results in an empty string, this is assumed to be the case. The certificate file may also contain intermediate @@ -25284,13 +26983,22 @@ this). There is one other option that may be needed in other situations. If tls_dhparam = /some/file/name .endd is set, the SSL library is initialized for the use of Diffie-Hellman ciphers -with the parameters contained in the file. This increases the set of cipher -suites that the server supports. See the command +with the parameters contained in the file. +Set this to &`none`& to disable use of DH entirely, by making no prime +available: +.code +tls_dhparam = none +.endd +This may also be set to a string identifying a standard prime to be used for +DH; if it is set to &`default`& or, for OpenSSL, is unset, then the prime +used is &`ike23`&. There are a few standard primes available, see the +documentation for &%tls_dhparam%& for the complete list. + +See the command .code openssl dhparam .endd -for a way of generating this data. At present, &%tls_dhparam%& is used only -when Exim is linked with OpenSSL. It is ignored if GnuTLS is being used. +for a way of generating file data. The strings supplied for these three options are expanded every time a client host connects. It is therefore possible to use different certificates and keys @@ -25300,15 +27008,13 @@ forced to fail, Exim behaves as if the option is not set. .cindex "cipher" "logging" .cindex "log" "TLS cipher" -.vindex "&$tls_cipher$&" -The variable &$tls_cipher$& is set to the cipher suite that was negotiated for +.vindex "&$tls_in_cipher$&" +The variable &$tls_in_cipher$& is set to the cipher suite that was negotiated for an incoming TLS connection. It is included in the &'Received:'& header of an incoming message (by default &-- you can, of course, change this), and it is also included in the log line that records a message's arrival, keyed by &"X="&, unless the &%tls_cipher%& log selector is turned off. The &%encrypted%& condition can be used to test for specific cipher suites in ACLs. -(For outgoing SMTP deliveries, &$tls_cipher$& is reset &-- see section -&<>&.) Once TLS has been established, the ACLs that run for subsequent SMTP commands can check the name of the cipher suite and vary their actions accordingly. The @@ -25317,6 +27023,9 @@ example, OpenSSL uses the name DES-CBC3-SHA for the cipher suite which in other contexts is known as TLS_RSA_WITH_3DES_EDE_CBC_SHA. Check the OpenSSL or GnuTLS documentation for more details. +For outgoing SMTP deliveries, &$tls_out_cipher$& is used and logged +(again depending on the &%tls_cipher%& log selector). + .section "Requesting and verifying client certificates" "SECID183" .cindex "certificate" "verification of client" @@ -25327,8 +27036,10 @@ session with a client, you must set either &%tls_verify_hosts%& or apply to all TLS connections. For any host that matches one of these options, Exim requests a certificate as part of the setup of the TLS session. The contents of the certificate are verified by comparing it with a list of -expected certificates. These must be available in a file or, -for OpenSSL only (not GnuTLS), a directory, identified by +expected certificates. +These may be the system default set (depending on library version), +an explicit file or, +depending on library version, a directory, identified by &%tls_verify_certificates%&. A file can contain multiple certificates, concatenated end to end. If a @@ -25353,29 +27064,100 @@ fact that no certificate was verified, and vary their actions accordingly. For example, you can insist on a certificate before accepting a message for relaying, but not when the message is destined for local delivery. -.vindex "&$tls_peerdn$&" +.vindex "&$tls_in_peerdn$&" When a client supplies a certificate (whether it verifies or not), the value of the Distinguished Name of the certificate is made available in the variable -&$tls_peerdn$& during subsequent processing of the message. +&$tls_in_peerdn$& during subsequent processing of the message. .cindex "log" "distinguished name" Because it is often a long text string, it is not included in the log line or &'Received:'& header by default. You can arrange for it to be logged, keyed by &"DN="&, by setting the &%tls_peerdn%& log selector, and you can use &%received_header_text%& to change the &'Received:'& header. When no -certificate is supplied, &$tls_peerdn$& is empty. +certificate is supplied, &$tls_in_peerdn$& is empty. .section "Revoked certificates" "SECID184" .cindex "TLS" "revoked certificates" .cindex "revocation list" .cindex "certificate" "revocation list" +.cindex "OCSP" "stapling" Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when certificates are revoked. If you have such a list, you can pass it to an Exim server using the global option called &%tls_crl%& and to an Exim client using an identically named option for the &(smtp)& transport. In each case, the value of the option is expanded and must then be the name of a file that contains a CRL in PEM format. +The downside is that clients have to periodically re-download a potentially huge +file from every certificate authority they know of. + +The way with most moving parts at query time is Online Certificate +Status Protocol (OCSP), where the client verifies the certificate +against an OCSP server run by the CA. This lets the CA track all +usage of the certs. It requires running software with access to the +private key of the CA, to sign the responses to the OCSP queries. OCSP +is based on HTTP and can be proxied accordingly. + +The only widespread OCSP server implementation (known to this writer) +comes as part of OpenSSL and aborts on an invalid request, such as +connecting to the port and then disconnecting. This requires +re-entering the passphrase each time some random client does this. + +The third way is OCSP Stapling; in this, the server using a certificate +issued by the CA periodically requests an OCSP proof of validity from +the OCSP server, then serves it up inline as part of the TLS +negotiation. This approach adds no extra round trips, does not let the +CA track users, scales well with number of certs issued by the CA and is +resilient to temporary OCSP server failures, as long as the server +starts retrying to fetch an OCSP proof some time before its current +proof expires. The downside is that it requires server support. + +Unless Exim is built with the support disabled, +.new +or with GnuTLS earlier than version 3.3.16 / 3.4.8 +.wen +support for OCSP stapling is included. + +There is a global option called &%tls_ocsp_file%&. +The file specified therein is expected to be in DER format, and contain +an OCSP proof. Exim will serve it as part of the TLS handshake. This +option will be re-expanded for SNI, if the &%tls_certificate%& option +contains &`tls_in_sni`&, as per other TLS options. + +Exim does not at this time implement any support for fetching a new OCSP +proof. The burden is on the administrator to handle this, outside of +Exim. The file specified should be replaced atomically, so that the +contents are always valid. Exim will expand the &%tls_ocsp_file%& option +on each connection, so a new file will be handled transparently on the +next connection. + +When built with OpenSSL Exim will check for a valid next update timestamp +in the OCSP proof; if not present, or if the proof has expired, it will be +ignored. + +For the client to be able to verify the stapled OCSP the server must +also supply, in its stapled information, any intermediate +certificates for the chain leading to the OCSP proof from the signer +of the server certificate. There may be zero or one such. These +intermediate certificates should be added to the server OCSP stapling +file named by &%tls_ocsp_file%&. + +Note that the proof only covers the terminal server certificate, +not any of the chain from CA to it. + +There is no current way to staple a proof for a client certificate. + +.code + A helper script "ocsp_fetch.pl" for fetching a proof from a CA + OCSP server is supplied. The server URL may be included in the + server certificate, if the CA is helpful. + + One failure mode seen was the OCSP Signer cert expiring before the end + of validity of the OCSP proof. The checking done by Exim/OpenSSL + noted this as invalid overall, but the re-fetch script did not. +.endd + + .section "Configuring an Exim client to use TLS" "SECID185" @@ -25419,11 +27201,34 @@ if it requests it. If the server is Exim, it will request a certificate only if &%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client. If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it +specifies a collection of expected server certificates. +These may be the system default set (depending on library version), +a file or, +depending on library version, a directory, must name a file or, -for OpenSSL only (not GnuTLS), a directory, that contains a collection of -expected server certificates. The client verifies the server's certificate +for OpenSSL only (not GnuTLS), a directory. +The client verifies the server's certificate against this collection, taking into account any revoked certificates that are in the list defined by &%tls_crl%&. +Failure to verify fails the TLS connection unless either of the +&%tls_verify_hosts%& or &%tls_try_verify_hosts%& options are set. + +The &%tls_verify_hosts%& and &%tls_try_verify_hosts%& options restrict +certificate verification to the listed servers. Verification either must +or need not succeed respectively. + +The &(smtp)& transport has two OCSP-related options: +&%hosts_require_ocsp%&; a host-list for which a Certificate Status +is requested and required for the connection to proceed. The default +value is empty. +&%hosts_request_ocsp%&; a host-list for which (additionally) +a Certificate Status is requested (but not necessarily verified). The default +value is "*" meaning that requests are made unless configured +otherwise. + +The host(s) should also be in &%hosts_require_tls%&, and +&%tls_verify_certificates%& configured for the transport, +for OCSP to be relevant. If &%tls_require_ciphers%& is set on the &(smtp)& transport, it must contain a @@ -25444,12 +27249,12 @@ All the TLS options in the &(smtp)& transport are expanded before use, with which the client is connected. Forced failure of an expansion causes Exim to behave as if the relevant option were unset. -.vindex &$tls_bits$& -.vindex &$tls_cipher$& -.vindex &$tls_peerdn$& -.vindex &$tls_sni$& +.vindex &$tls_out_bits$& +.vindex &$tls_out_cipher$& +.vindex &$tls_out_peerdn$& +.vindex &$tls_out_sni$& Before an SMTP connection is established, the -&$tls_bits$&, &$tls_cipher$&, &$tls_peerdn$& and &$tls_sni$& +&$tls_out_bits$&, &$tls_out_cipher$&, &$tls_out_peerdn$& and &$tls_out_sni$& variables are emptied. (Until the first connection, they contain the values that were set when the message was received.) If STARTTLS is subsequently successfully obeyed, these variables are set to the relevant values for the @@ -25457,11 +27262,10 @@ outgoing connection. -.new .section "Use of TLS Server Name Indication" "SECTtlssni" .cindex "TLS" "Server Name Indication" -.vindex "&$tls_sni$&" -.oindex "&%tls_sni%&" +.vindex "&$tls_in_sni$&" +.oindex "&%tls_in_sni%&" With TLS1.0 or above, there is an extension mechanism by which extra information can be included at various points in the protocol. One of these extensions, documented in RFC 6066 (and before that RFC 4366) is @@ -25470,7 +27274,7 @@ client in the initial handshake, so that the server can examine the servername within and possibly choose to use different certificates and keys (and more) for this session. -This is analagous to HTTP's &"Host:"& header, and is the main mechanism by +This is analogous to HTTP's &"Host:"& header, and is the main mechanism by which HTTPS-enabled web-sites can be virtual-hosted, many sites to one IP address. @@ -25488,14 +27292,14 @@ different clients. Or even negotiate different cipher suites. The &%tls_sni%& option on an SMTP transport is an expanded string; the result, if not empty, will be sent on a TLS session as part of the handshake. There's nothing more to it. Choosing a sensible value not derived insecurely is the -only point of caution. The &$tls_sni$& variable will be set to this string +only point of caution. The &$tls_out_sni$& variable will be set to this string for the lifetime of the client connection (including during authentication). -Except during SMTP client sessions, if &$tls_sni$& is set then it is a string +Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string received from a client. It can be logged with the &%log_selector%& item &`+tls_sni`&. -If the string &`tls_sni`& appears in the main section's &%tls_certificate%& +If the string &`tls_in_sni`& appears in the main section's &%tls_certificate%& option (prior to expansion) then the following options will be re-expanded during TLS session handshake, to permit alternative values to be chosen: @@ -25511,6 +27315,9 @@ during TLS session handshake, to permit alternative values to be chosen: .next .vindex "&%tls_verify_certificates%&" &%tls_verify_certificates%& +.next +.vindex "&%tls_ocsp_file%&" +&%tls_ocsp_file%& .endlist Great care should be taken to deal with matters of case, various injection @@ -25521,7 +27328,7 @@ arbitrary unverified data provided prior to authentication. The Exim developers are proceeding cautiously and so far no other TLS options are re-expanded. -When Exim is built againt OpenSSL, OpenSSL must have been built with support +When Exim is built against OpenSSL, OpenSSL must have been built with support for TLS Extensions. This holds true for OpenSSL 1.0.0+ and 0.9.8+ with enable-tlsext in EXTRACONFIGURE. If you invoke &(openssl s_client -h)& and see &`-servername`& in the output, then OpenSSL has support. @@ -25529,7 +27336,6 @@ see &`-servername`& in the output, then OpenSSL has support. When Exim is built against GnuTLS, SNI support is available as of GnuTLS 0.5.10. (Its presence predates the current API which Exim uses, so if Exim built, then you have SNI support). -.wen @@ -25603,11 +27409,19 @@ validation to succeed, of course, but if it's not preinstalled, sending the root certificate along with the rest makes it available for the user to install if the receiving end is a client MUA that can interact with a user. +Note that certificates using MD5 are unlikely to work on today's Internet; +even if your libraries allow loading them for use in Exim when acting as a +server, increasingly clients will not accept such certificates. The error +diagnostics in such a case can be frustratingly vague. + + .section "Self-signed certificates" "SECID187" .cindex "certificate" "self-signed" You can create a self-signed certificate using the &'req'& command provided with OpenSSL, like this: +. ==== Do not shorten the duration here without reading and considering +. ==== the text below. Please leave it at 9999 days. .code openssl req -x509 -newkey rsa:1024 -keyout file1 -out file2 \ -days 9999 -nodes @@ -25620,6 +27434,22 @@ that you are prompted for, and any use that is made of the key causes more prompting for the passphrase. This is not helpful if you are going to use this certificate and key in an MTA, where prompting is not possible. +. ==== I expect to still be working 26 years from now. The less technical +. ==== debt I create, in terms of storing up trouble for my later years, the +. ==== happier I will be then. We really have reached the point where we +. ==== should start, at the very least, provoking thought and making folks +. ==== pause before proceeding, instead of leaving all the fixes until two +. ==== years before 2^31 seconds after the 1970 Unix epoch. +. ==== -pdp, 2012 +NB: we are now past the point where 9999 days takes us past the 32-bit Unix +epoch. If your system uses unsigned time_t (most do) and is 32-bit, then +the above command might produce a date in the past. Think carefully about +the lifetime of the systems you're deploying, and either reduce the duration +of the certificate or reconsider your platform deployment. (At time of +writing, reducing the duration is the most likely choice, but the inexorable +progression of time takes us steadily towards an era where this will not +be a sensible resolution). + A self-signed certificate made in this way is sufficient for testing, and may be adequate for all your requirements if you are mainly interested in encrypting transfers, and not in secure identification. @@ -25673,9 +27503,6 @@ a realistic ACL for checking RCPT commands. This is discussed in chapter .section "Testing ACLs" "SECID188" The &%-bh%& command line option provides a way of testing your ACL configuration locally by running a fake SMTP session with which you interact. -The host &'relay-test.mail-abuse.org'& provides a service for checking your -relaying configuration (see section &<>& for more details). - .section "Specifying when ACLs are used" "SECID189" @@ -25688,6 +27515,7 @@ options in the main part of the configuration. These options are: .cindex "EXPN" "ACL for" .cindex "HELO" "ACL for" .cindex "EHLO" "ACL for" +.cindex "DKIM" "ACL for" .cindex "MAIL" "ACL for" .cindex "QUIT, ACL for" .cindex "RCPT" "ACL for" @@ -25696,6 +27524,7 @@ options in the main part of the configuration. These options are: .cindex "SMTP" "connection, ACL for" .cindex "non-SMTP messages" "ACLs for" .cindex "MIME content scanning" "ACL for" +.cindex "PRDR" "ACL for" .table2 140pt .irow &%acl_not_smtp%& "ACL for non-SMTP messages" @@ -25704,6 +27533,8 @@ options in the main part of the configuration. These options are: .irow &%acl_smtp_auth%& "ACL for AUTH" .irow &%acl_smtp_connect%& "ACL for start of SMTP connection" .irow &%acl_smtp_data%& "ACL after DATA is complete" +.irow &%acl_smtp_data_prdr%& "ACL for each recipient, after DATA is complete" +.irow &%acl_smtp_dkim%& "ACL for each DKIM signer" .irow &%acl_smtp_etrn%& "ACL for ETRN" .irow &%acl_smtp_expn%& "ACL for EXPN" .irow &%acl_smtp_helo%& "ACL for HELO or EHLO" @@ -25786,6 +27617,12 @@ Note that a client may issue more than one EHLO or HELO command in an SMTP session, and indeed is required to issue a new EHLO or HELO after successfully setting up encryption following a STARTTLS command. +.new +Note also that a deny neither forces the client to go away nor means that +mail will be refused on the connection. Consider checking for +&$sender_helo_name$& being defined in a MAIL or RCPT ACL to do that. +.wen + If the command is accepted by an &%accept%& verb that has a &%message%& modifier, the message may not contain more than one line (it will be truncated at the first newline and a panic logged if it does). Such a message cannot @@ -25818,6 +27655,10 @@ before or after the data) correctly &-- they keep the message on their queues and try again later, but that is their problem, though it does waste some of your resources. +The &%acl_smtp_data%& ACL is run after +the &%acl_smtp_data_prdr%&, +the &%acl_smtp_dkim%& +and the &%acl_smtp_mime%& ACLs. .section "The SMTP DKIM ACL" "SECTDKIMACL" The &%acl_smtp_dkim%& ACL is available only when Exim is compiled with DKIM support @@ -25827,20 +27668,61 @@ The ACL test specified by &%acl_smtp_dkim%& happens after a message has been received, and is executed for each DKIM signature found in a message. If not otherwise specified, the default action is to accept. -For details on the operation of DKIM, see chapter &<>&. +This ACL is evaluated before &%acl_smtp_mime%& and &%acl_smtp_data%&. + +For details on the operation of DKIM, see chapter &<>&. .section "The SMTP MIME ACL" "SECID194" The &%acl_smtp_mime%& option is available only when Exim is compiled with the content-scanning extension. For details, see chapter &<>&. +This ACL is evaluated after &%acl_smtp_dkim%& but before &%acl_smtp_data%&. + + +.section "The SMTP PRDR ACL" "SECTPRDRACL" +.cindex "PRDR" "ACL for" +.oindex "&%prdr_enable%&" +The &%acl_smtp_data_prdr%& ACL is available only when Exim is compiled +with PRDR support enabled (which is the default). +It becomes active only when the PRDR feature is negotiated between +client and server for a message, and more than one recipient +has been accepted. + +The ACL test specified by &%acl_smtp_data_prdr%& happens after a message +has been received, and is executed once for each recipient of the message +with &$local_part$& and &$domain$& valid. +The test may accept, defer or deny for individual recipients. +The &%acl_smtp_data%& will still be called after this ACL and +can reject the message overall, even if this ACL has accepted it +for some or all recipients. + +PRDR may be used to support per-user content filtering. Without it +one must defer any recipient after the first that has a different +content-filter configuration. With PRDR, the RCPT-time check +.new +.cindex "PRDR" "variable for" +for this can be disabled when the variable &$prdr_requested$& +is &"yes"&. +.wen +Any required difference in behaviour of the main DATA-time +ACL should however depend on the PRDR-time ACL having run, as Exim +will avoid doing so in some situations (e.g. single-recipient mails). + +See also the &%prdr_enable%& global option +and the &%hosts_try_prdr%& smtp transport option. + +This ACL is evaluated after &%acl_smtp_dkim%& but before &%acl_smtp_data%&. +If the ACL is not defined, processing completes as if +the feature was not requested by the client. .section "The QUIT ACL" "SECTQUITACL" .cindex "QUIT, ACL for" The ACL for the SMTP QUIT command is anomalous, in that the outcome of the ACL does not affect the response code to QUIT, which is always 221. Thus, the ACL -does not in fact control any access. For this reason, the only verbs that are -permitted are &%accept%& and &%warn%&. +does not in fact control any access. +For this reason, it may only accept +or warn as its final result. This ACL can be used for tasks such as custom logging at the end of an SMTP session. For example, you can use ACL variables in other ACLs to count @@ -25864,7 +27746,7 @@ connection is closed. In these special cases, the QUIT ACL does not run. .section "The not-QUIT ACL" "SECTNOTQUITACL" .vindex &$acl_smtp_notquit$& The not-QUIT ACL, specified by &%acl_smtp_notquit%&, is run in most cases when -an SMTP session ends without sending QUIT. However, when Exim itself is is bad +an SMTP session ends without sending QUIT. However, when Exim itself is in bad trouble, such as being unable to write to its log files, this ACL is not run, because it might try to do things (such as write to log files) that make the situation even worse. @@ -26218,8 +28100,8 @@ duplicates to be written, use the &%logwrite%& modifier instead. If &%log_message%& is not present, a &%warn%& verb just checks its conditions and obeys any &"immediate"& modifiers (such as &%control%&, &%set%&, -&%logwrite%&, and &%add_header%&) that appear before the first failing -condition. There is more about adding header lines in section +&%logwrite%&, &%add_header%&, and &%remove_header%&) that appear before the +first failing condition. There is more about adding header lines in section &<>&. If any condition on a &%warn%& statement cannot be completed (that is, there is @@ -26337,7 +28219,7 @@ others specify text for messages that are used when access is denied or a warning is generated. The &%control%& modifier affects the way an incoming message is handled. -The positioning of the modifiers in an ACL statement important, because the +The positioning of the modifiers in an ACL statement is important, because the processing of a verb ceases as soon as its outcome is known. Only those modifiers that have already been encountered will take effect. For example, consider this use of the &%message%& modifier: @@ -26458,12 +28340,12 @@ If you want to apply a control unconditionally, you can use it with a .vitem &*delay*&&~=&~<&'time'&> .cindex "&%delay%& ACL modifier" .oindex "&%-bh%&" -This modifier may appear in any ACL. It causes Exim to wait for the time -interval before proceeding. However, when testing Exim using the &%-bh%& -option, the delay is not actually imposed (an appropriate message is output -instead). The time is given in the usual Exim notation, and the delay happens -as soon as the modifier is processed. In an SMTP session, pending output is -flushed before the delay is imposed. +This modifier may appear in any ACL except notquit. It causes Exim to wait for +the time interval before proceeding. However, when testing Exim using the +&%-bh%& option, the delay is not actually imposed (an appropriate message is +output instead). The time is given in the usual Exim notation, and the delay +happens as soon as the modifier is processed. In an SMTP session, pending +output is flushed before the delay is imposed. Like &%control%&, &%delay%& can be used with &%accept%& or &%deny%&, for example: @@ -26510,7 +28392,7 @@ confusing to some people, so the use of &%endpass%& is no longer recommended as This modifier sets up a message that is used as part of the log message if the ACL denies access or a &%warn%& statement's conditions are true. For example: .code -require log_message = wrong cipher suite $tls_cipher +require log_message = wrong cipher suite $tls_in_cipher encrypted = DES-CBC3-SHA .endd &%log_message%& is also used when recipients are discarded by &%discard%&. For @@ -26644,6 +28526,9 @@ anyway. If the message contains newlines, this gives rise to a multi-line SMTP response. .vindex "&$acl_verify_message$&" +For ACLs that are called by an &%acl =%& ACL condition, the message is +stored in &$acl_verify_message$&, from which the calling ACL may use it. + If &%message%& is used on a statement that verifies an address, the message specified overrides any message that is generated by the verification process. However, the original message is available in the variable @@ -26661,13 +28546,33 @@ all the conditions are true, wherever it appears in an ACL command, whereas effect. +.vitem &*remove_header*&&~=&~<&'text'&> +This modifier specifies one or more header names in a colon-separated list + that are to be removed from an incoming message, assuming, of course, that +the message is ultimately accepted. For details, see section &<>&. + + .vitem &*set*&&~<&'acl_name'&>&~=&~<&'value'&> .cindex "&%set%& ACL modifier" This modifier puts a value into one of the ACL variables (see section &<>&). -.endlist +.vitem &*udpsend*&&~=&~<&'parameters'&> +This modifier sends a UDP packet, for purposes such as statistics +collection or behaviour monitoring. The parameters are expanded, and +the result of the expansion must be a colon-separated list consisting +of a destination server, port number, and the packet contents. The +server can be specified as a host name or IPv4 or IPv6 address. The +separator can be changed with the usual angle bracket syntax. For +example, you might want to collect information on which hosts connect +when: +.code +udpsend = <; 2001:dB8::dead:beef ; 1234 ;\ + $tod_zulu $sender_host_address +.endd +.endlist + @@ -26727,6 +28632,60 @@ Notice that we put back the lower cased version afterwards, assuming that is what is wanted for subsequent tests. +.vitem &*control&~=&~cutthrough_delivery*& +.cindex "&ACL;" "cutthrough routing" +.cindex "cutthrough" "requesting" +This option requests delivery be attempted while the item is being received. + +The option is usable in the RCPT ACL. +If enabled for a message received via smtp and routed to an smtp transport, +and only one transport, interface, destination host and port combination +is used for all recipients of the message, +then the delivery connection is made while the receiving connection is open +and data is copied from one to the other. + +An attempt to set this option for any recipient but the first +for a mail will be quietly ignored. +If a recipient-verify callout +.new +(with use_sender) +.wen +connection is subsequently +requested in the same ACL it is held open and used for +any subsequent recipients and the data, +otherwise one is made after the initial RCPT ACL completes. + +Note that routers are used in verify mode, +and cannot depend on content of received headers. +Note also that headers cannot be +modified by any of the post-data ACLs (DATA, MIME and DKIM). +Headers may be modified by routers (subject to the above) and transports. + +.new +All the usual ACLs are called; if one results in the message being +rejected, all effort spent in delivery (including the costs on +the ultimate destination) will be wasted. +Note that in the case of data-time ACLs this includes the entire +message body. +.wen + +Cutthrough delivery is not supported via transport-filters or when DKIM signing +of outgoing messages is done, because it sends data to the ultimate destination +before the entire message has been received from the source. +It is not supported for messages received with the SMTP PRDR option in use. + +Should the ultimate destination system positively accept or reject the mail, +a corresponding indication is given to the source system and nothing is queued. +If there is a temporary error the item is queued for later delivery in the +usual fashion. If the item is successfully delivered in cutthrough mode +the delivery log lines are tagged with ">>" rather than "=>" and appear +before the acceptance "<=" line. + +Delivery in this mode avoids the generation of a bounce mail to a +(possibly faked) +sender when the destination system is doing content-scan based rejection. + + .vitem &*control&~=&~debug/*&<&'options'&> .cindex "&ACL;" "enabling debug logging" .cindex "debugging" "enabling from an ACL" @@ -26745,6 +28704,30 @@ contexts): .endd +.vitem &*control&~=&~dkim_disable_verify*& +.cindex "disable DKIM verify" +.cindex "DKIM" "disable verify" +This control turns off DKIM verification processing entirely. For details on +the operation and configuration of DKIM, see chapter &<>&. + + +.vitem &*control&~=&~dscp/*&<&'value'&> +.cindex "&ACL;" "setting DSCP value" +.cindex "DSCP" "inbound" +This option causes the DSCP value associated with the socket for the inbound +connection to be adjusted to a given value, given as one of a number of fixed +strings or to numeric value. +The &%-bI:dscp%& option may be used to ask Exim which names it knows of. +Common values include &`throughput`&, &`mincost`&, and on newer systems +&`ef`&, &`af41`&, etc. Numeric values may be in the range 0 to 0x3F. + +The outbound packets from Exim will be marked with this value in the header +(for IPv4, the TOS field; for IPv6, the TCLASS field); there is no guarantee +that these values will have any effect, not be stripped by networking +equipment, or do much of anything without cooperation with your Network +Engineer and those of all network operators between the source and destination. + + .vitem &*control&~=&~enforce_sync*& &&& &*control&~=&~no_enforce_sync*& .cindex "SMTP" "synchronization checking" @@ -26913,6 +28896,13 @@ data is read. &*Note:*& This control applies only to the current message, not to any others that are being submitted at the same time using &%-bs%& or &%-bS%&. + +.new +.vitem &*control&~=&~utf8_downconvert*& +This control enables conversion of UTF-8 in message addresses +to a-label form. +For details see &<>&. +.wen .endlist vlist @@ -26935,7 +28925,7 @@ Remotely submitted, fixups applied: use &`control = submission`&. .section "Adding header lines in ACLs" "SECTaddheadacl" .cindex "header lines" "adding in an ACL" .cindex "header lines" "position of added lines" -.cindex "&%message%& ACL modifier" +.cindex "&%add_header%& ACL modifier" The &%add_header%& modifier can be used to add one or more extra header lines to an incoming message, as in this example: .code @@ -26944,13 +28934,18 @@ warn dnslists = sbl.spamhaus.org : \ add_header = X-blacklisted-at: $dnslist_domain .endd The &%add_header%& modifier is permitted in the MAIL, RCPT, PREDATA, DATA, -MIME, and non-SMTP ACLs (in other words, those that are concerned with +MIME, DKIM, and non-SMTP ACLs (in other words, those that are concerned with receiving a message). The message must ultimately be accepted for &%add_header%& to have any significant effect. You can use &%add_header%& with any ACL verb, including &%deny%& (though this is potentially useful only in a RCPT ACL). -If the data for the &%add_header%& modifier contains one or more newlines that +Headers will not be added to the message if the modifier is used in +DATA, MIME or DKIM ACLs for messages delivered by cutthrough routing. + +Leading and trailing newlines are removed from +the data for the &%add_header%& modifier; if it then +contains one or more newlines that are not followed by a space or a tab, it is assumed to contain multiple header lines. Each one is checked for valid syntax; &`X-ACL-Warn:`& is added to the front of any line that is not a valid header line. @@ -26968,7 +28963,9 @@ message is rejected after DATA or by the non-SMTP ACL, all added header lines are included in the entry that is written to the reject log. .cindex "header lines" "added; visibility of" -Header lines are not visible in string expansions until they are added to the +Header lines are not visible in string expansions +of message headers +until they are added to the message. It follows that header lines defined in the MAIL, RCPT, and predata ACLs are not visible until the DATA ACL and MIME ACLs are run. Similarly, header lines that are added by the DATA or MIME ACLs are not visible in those @@ -26977,7 +28974,9 @@ passing data between (for example) the MAIL and RCPT ACLs. If you want to do this, you can use ACL variables, as described in section &<>&. -The &%add_header%& modifier acts immediately it is encountered during the +The list of headers yet to be added is given by the &%$headers_added%& variable. + +The &%add_header%& modifier acts immediately as it is encountered during the processing of an ACL. Notice the difference between these two cases: .display &`accept add_header = ADDED: some text`& @@ -27026,10 +29025,83 @@ system filter or in a router or transport. +.section "Removing header lines in ACLs" "SECTremoveheadacl" +.cindex "header lines" "removing in an ACL" +.cindex "header lines" "position of removed lines" +.cindex "&%remove_header%& ACL modifier" +The &%remove_header%& modifier can be used to remove one or more header lines +from an incoming message, as in this example: +.code +warn message = Remove internal headers + remove_header = x-route-mail1 : x-route-mail2 +.endd +The &%remove_header%& modifier is permitted in the MAIL, RCPT, PREDATA, DATA, +MIME, DKIM, and non-SMTP ACLs (in other words, those that are concerned with +receiving a message). The message must ultimately be accepted for +&%remove_header%& to have any significant effect. You can use &%remove_header%& +with any ACL verb, including &%deny%&, though this is really not useful for +any verb that doesn't result in a delivered message. + +Headers will not be removed to the message if the modifier is used in +DATA, MIME or DKIM ACLs for messages delivered by cutthrough routing. + +More than one header can be removed at the same time by using a colon separated +list of header names. The header matching is case insensitive. Wildcards are +not permitted, nor is list expansion performed, so you cannot use hostlists to +create a list of headers, however both connection and message variable expansion +are performed (&%$acl_c_*%& and &%$acl_m_*%&), illustrated in this example: +.code +warn hosts = +internal_hosts + set acl_c_ihdrs = x-route-mail1 : x-route-mail2 +warn message = Remove internal headers + remove_header = $acl_c_ihdrs +.endd +Removed header lines are accumulated during the MAIL, RCPT, and predata ACLs. +They are removed from the message before processing the DATA and MIME ACLs. +There is no harm in attempting to remove the same header twice nor is removing +a non-existent header. Further header lines to be removed may be accumulated +during the DATA and MIME ACLs, after which they are removed from the message, +if present. In the case of non-SMTP messages, headers to be removed are +accumulated during the non-SMTP ACLs, and are removed from the message after +all the ACLs have run. If a message is rejected after DATA or by the non-SMTP +ACL, there really is no effect because there is no logging of what headers +would have been removed. + +.cindex "header lines" "removed; visibility of" +Header lines are not visible in string expansions until the DATA phase when it +is received. Any header lines removed in the MAIL, RCPT, and predata ACLs are +not visible in the DATA ACL and MIME ACLs. Similarly, header lines that are +removed by the DATA or MIME ACLs are still visible in those ACLs. Because of +this restriction, you cannot use header lines as a way of controlling data +passed between (for example) the MAIL and RCPT ACLs. If you want to do this, +you should instead use ACL variables, as described in section +&<>&. + +The &%remove_header%& modifier acts immediately as it is encountered during the +processing of an ACL. Notice the difference between these two cases: +.display +&`accept remove_header = X-Internal`& +&` `&<&'some condition'&> + +&`accept `&<&'some condition'&> +&` remove_header = X-Internal`& +.endd +In the first case, the header line is always removed, whether or not the +condition is true. In the second case, the header line is removed only if the +condition is true. Multiple occurrences of &%remove_header%& may occur in the +same ACL statement. All those that are encountered before a condition fails +are honoured. + +&*Warning*&: This facility currently applies only to header lines that are +present during ACL processing. It does NOT remove header lines that are added +in a system filter or in a router or transport. + + + .section "ACL conditions" "SECTaclconditions" .cindex "&ACL;" "conditions; list of" -Some of conditions listed in this section are available only when Exim is +Some of the conditions listed in this section are available only when Exim is compiled with the content-scanning extension. They are included here briefly for completeness. More detailed descriptions can be found in the discussion on content scanning in chapter &<>&. @@ -27047,6 +29119,7 @@ The conditions are as follows: .vitem &*acl&~=&~*&<&'name&~of&~acl&~or&~ACL&~string&~or&~file&~name&~'&> .cindex "&ACL;" "nested" .cindex "&ACL;" "indirect" +.cindex "&ACL;" "arguments" .cindex "&%acl%& ACL condition" The possible values of the argument are the same as for the &%acl_smtp_%&&'xxx'& options. The named or inline ACL is run. If it returns @@ -27056,6 +29129,14 @@ condition is on a &%warn%& verb. In that case, a &"defer"& return makes the condition false. This means that further processing of the &%warn%& verb ceases, but processing of the ACL continues. +If the argument is a named ACL, up to nine space-separated optional values +can be appended; they appear within the called ACL in $acl_arg1 to $acl_arg9, +and $acl_narg is set to the count of values. +Previous values of these variables are restored after the call returns. +The name and values are expanded separately. +Note that spaces in complex expansions which are used as arguments +will act as argument separators. + If the nested &%acl%& returns &"drop"& and the outer condition denies access, the connection is dropped. If it returns &"discard"&, the verb must be &%accept%& or &%discard%&, and the action is taken immediately &-- no further @@ -27144,7 +29225,7 @@ encrypted = * .endd -.vitem &*hosts&~=&~*&<&'&~host&~list'&> +.vitem &*hosts&~=&~*&<&'host&~list'&> .cindex "&%hosts%& ACL condition" .cindex "host" "ACL checking" .cindex "&ACL;" "testing the client host" @@ -27286,6 +29367,21 @@ This condition checks whether the sending host (the client) is authorized to send email. Details of how this works are given in section &<>&. +.vitem &*verify&~=&~header_names_ascii*& +.cindex "&%verify%& ACL condition" +.cindex "&ACL;" "verifying header names only ASCII" +.cindex "header lines" "verifying header names only ASCII" +.cindex "verifying" "header names only ASCII" +This condition is relevant only in an ACL that is run after a message has been +received, that is, in an ACL specified by &%acl_smtp_data%& or +&%acl_not_smtp%&. It checks all header names (not the content) to make sure +there are no non-ASCII characters, also excluding control characters. The +allowable characters are decimal ASCII values 33 through 126. + +Exim itself will handle headers with non-ASCII characters, but it can cause +problems for downstream applications, so this option will allow their +detection and rejection in the DATA ACL's. + .vitem &*verify&~=&~header_sender/*&<&'options'&> .cindex "&%verify%& ACL condition" .cindex "&ACL;" "verifying sender in the header" @@ -27321,7 +29417,8 @@ This condition is relevant only in an ACL that is run after a message has been received, that is, in an ACL specified by &%acl_smtp_data%& or &%acl_not_smtp%&. It checks the syntax of all header lines that can contain lists of addresses (&'Sender:'&, &'From:'&, &'Reply-To:'&, &'To:'&, &'Cc:'&, -and &'Bcc:'&). Unqualified addresses (local parts without domains) are +and &'Bcc:'&), returning true if there are no problems. +Unqualified addresses (local parts without domains) are permitted only in locally generated messages and from hosts that match &%sender_unqualified_hosts%& or &%recipient_unqualified_hosts%&, as appropriate. @@ -27381,7 +29478,7 @@ verified is redirected to a single address, verification continues with the new address, and in that case, the subsequent value of &$address_data$& is the value for the child address. -.vitem &*verify&~=&~reverse_host_lookup*& +.vitem &*verify&~=&~reverse_host_lookup/*&<&'options'&> .cindex "&%verify%& ACL condition" .cindex "&ACL;" "verifying host reverse lookup" .cindex "host" "verifying reverse lookup" @@ -27392,6 +29489,9 @@ Verification ensures that the host name obtained from a reverse DNS lookup, or one of its aliases, does, when it is itself looked up in the DNS, yield the original IP address. +There is one possible option, &`defer_ok`&. If this is present and a +DNS operation returns a temporary error, the verify condition succeeds. + If this condition is used for a locally generated message (that is, when there is no client host involved), it always succeeds. @@ -27480,9 +29580,15 @@ deny dnslists = blackholes.mail-abuse.org warn message = X-Warn: sending host is on dialups list dnslists = dialups.mail-abuse.org .endd -DNS list lookups are cached by Exim for the duration of the SMTP session, +.cindex cacheing "of dns lookup" +.cindex DNS TTL +DNS list lookups are cached by Exim for the duration of the SMTP session +.new +(but limited by the DNS return TTL value), +.wen so a lookup based on the IP address is done at most once for any incoming -connection. Exim does not share information between multiple incoming +connection (assuming long-enough TTL). +Exim does not share information between multiple incoming connections (but your local name server cache should be active). @@ -27804,7 +29910,7 @@ dnslists = a.b.c!&0.0.0.1 If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is false because 127.0.0.1 matches. .next -If &`!==`& or &`!=&&`& is used, the condition is true there is at least one +If &`!==`& or &`!=&&`& is used, the condition is true if there is at least one looked up IP address that does not match. Consider: .code dnslists = a.b.c!=&0.0.0.1 @@ -27897,6 +30003,13 @@ deny condition = ${if isip4{$sender_host_address}} dnslists = some.list.example .endd +If an explicit key is being used for a DNS lookup and it may be an IPv6 +address you should specify alternate list separators for both the outer +(DNS list name) list and inner (lookup keys) list: +.code + dnslists = <; dnsbl.example.com/<|$acl_m_addrslist +.endd + .section "Rate limiting incoming messages" "SECTratelimiting" .cindex "rate limiting" "client sending" .cindex "limiting client sending rates" @@ -27988,7 +30101,7 @@ The &%per_rcpt%& option causes Exim to limit the rate at which recipients are accepted. It can be used in the &%acl_smtp_rcpt%&, &%acl_smtp_predata%&, &%acl_smtp_mime%&, &%acl_smtp_data%&, or &%acl_smtp_rcpt%& ACLs. In &%acl_smtp_rcpt%& the rate is updated one recipient at a time; in the other -ACLs the rate is updated with the total recipient count in one go. Note that +ACLs the rate is updated with the total (accepted) recipient count in one go. Note that in either case the rate limiting engine will see a message with many recipients as a large high-speed burst. @@ -28278,6 +30391,7 @@ router that does not set up hosts routes to an &(smtp)& transport with a &%hosts%& setting, the transport's hosts are used. If an &(smtp)& transport has &%hosts_override%& set, its hosts are always used, whether or not the router supplies a host list. +Callouts are only supported on &(smtp)& transports. The port that is used is taken from the transport, if it is specified and is a remote transport. (For routers that do verification only, no transport need be @@ -28299,6 +30413,9 @@ following SMTP commands are sent: LHLO is used instead of HELO if the transport's &%protocol%& option is set to &"lmtp"&. +The callout may use EHLO, AUTH and/or STARTTLS given appropriate option +settings. + A recipient callout check is similar. By default, it also uses an empty address for the sender. This default is chosen because most hosts do not make use of the sender address when verifying a recipient. Using the same address means @@ -28814,16 +30931,16 @@ Suppose your LAN is 192.168.45.0/24. In the main part of the configuration, you put the following definitions: .code -domainlist local_domains = my.dom1.example : my.dom2.example -domainlist relay_domains = friend1.example : friend2.example -hostlist relay_hosts = 192.168.45.0/24 +domainlist local_domains = my.dom1.example : my.dom2.example +domainlist relay_to_domains = friend1.example : friend2.example +hostlist relay_from_hosts = 192.168.45.0/24 .endd Now you can use these definitions in the ACL that is run for every RCPT command: .code acl_check_rcpt: - accept domains = +local_domains : +relay_domains - accept hosts = +relay_hosts + accept domains = +local_domains : +relay_to_domains + accept hosts = +relay_from_hosts .endd The first statement accepts any RCPT command that contains an address in the local or relay domains. For any other domain, control passes to the second @@ -28840,14 +30957,6 @@ in chapter &<>&. You can check the relay characteristics of your configuration in the same way that you can test any ACL behaviour for an incoming SMTP connection, by using the &%-bh%& option to run a fake SMTP session with which you interact. - -For specifically testing for unwanted relaying, the host -&'relay-test.mail-abuse.org'& provides a useful service. If you telnet to this -host from the host on which Exim is running, using the normal telnet port, you -will see a normal telnet connection message and then quite a long delay. Be -patient. The remote host is making an SMTP connection back to your host, and -trying a number of common probes to test for open relay vulnerability. The -results of the tests will eventually appear on your terminal. .ecindex IIDacl @@ -28928,10 +31037,12 @@ It supports a &"generic"& interface to scanners called via the shell, and specialized interfaces for &"daemon"& type virus scanners, which are resident in memory and thus are much faster. +A timeout of 2 minutes is applied to a scanner call (by default); +if it expires then a defer action is taken. .oindex "&%av_scanner%&" -You can set the &%av_scanner%& option in first part of the Exim configuration -file to specify which scanner to use, together with any additional options that +You can set the &%av_scanner%& option in the main part of the configuration +to specify which scanner to use, together with any additional options that are needed. The basic syntax is as follows: .display &`av_scanner = <`&&'scanner-type'&&`>:<`&&'option1'&&`>:<`&&'option2'&&`>:[...]`& @@ -28941,9 +31052,44 @@ If you do not set &%av_scanner%&, it defaults to av_scanner = sophie:/var/run/sophie .endd If the value of &%av_scanner%& starts with a dollar character, it is expanded -before use. The following scanner types are supported in this release: +before use. +The usual list-parsing of the content (see &<>&) applies. +The following scanner types are supported in this release: .vlist +.vitem &%avast%& +.cindex "virus scanners" "avast" +This is the scanner daemon of Avast. It has been tested with Avast Core +Security (currently at version 1.1.7). +You can get a trial version at &url(http://www.avast.com) or for Linux +at &url(http://www.avast.com/linux-server-antivirus). +This scanner type takes one option, +which can be either a full path to a UNIX socket, +or host and port specifiers separated by white space. +The host may be a name or an IP address; the port is either a +single number or a pair of numbers with a dash between. +Any further options are given, on separate lines, +to the daemon as options before the main scan command. +For example: +.code +av_scanner = avast:/var/run/avast/scan.sock:FLAGS -fullfiles:SENSITIVITY -pup +av_scanner = avast:192.168.2.22 5036 +.endd +If you omit the argument, the default path +&_/var/run/avast/scan.sock_& +is used. +If you use a remote host, +you need to make Exim's spool directory available to it, +as the scanner is passed a file path, not file contents. +For information about available commands and their options you may use +.code +$ socat UNIX:/var/run/avast/scan.sock STDIO: + FLAGS + SENSITIVITY + PACK +.endd + + .vitem &%aveserver%& .cindex "virus scanners" "Kaspersky" This is the scanner daemon of Kaspersky Version 5. You can get a trial version @@ -28960,21 +31106,60 @@ av_scanner = aveserver:/var/run/aveserver This daemon-type scanner is GPL and free. You can get it at &url(http://www.clamav.net/). Some older versions of clamd do not seem to unpack MIME containers, so it used to be recommended to unpack MIME attachments -in the MIME ACL. This no longer believed to be necessary. One option is -required: either the path and name of a UNIX socket file, or a hostname or IP -number, and a port, separated by space, as in the second of these examples: +in the MIME ACL. This is no longer believed to be necessary. + +The options are a list of server specifiers, which may be +a UNIX socket specification, +a TCP socket specification, +or a (global) option. + +A socket specification consists of a space-separated list. +For a Unix socket the first element is a full path for the socket, +for a TCP socket the first element is the IP address +and the second a port number, +Any further elements are per-server (non-global) options. +These per-server options are supported: +.code +retry= Retry on connect fail +.endd + +The &`retry`& option specifies a time after which a single retry for +a failed connect is made. The default is to not retry. + +If a Unix socket file is specified, only one server is supported. + +Examples: .code av_scanner = clamd:/opt/clamd/socket av_scanner = clamd:192.0.2.3 1234 av_scanner = clamd:192.0.2.3 1234:local +av_scanner = clamd:192.0.2.3 1234 retry=10s +av_scanner = clamd:192.0.2.3 1234 : 192.0.2.4 1234 .endd -If the value of av_scanner points to a UNIX socket file or contains the local -keyword, then the ClamAV interface will pass a filename containing the data +If the value of av_scanner points to a UNIX socket file or contains the +&`local`& +option, then the ClamAV interface will pass a filename containing the data to be scanned, which will should normally result in less I/O happening and be more efficient. Normally in the TCP case, the data is streamed to ClamAV as Exim does not assume that there is a common filesystem with the remote host. There is an option WITH_OLD_CLAMAV_STREAM in &_src/EDITME_& available, should you be running a version of ClamAV prior to 0.95. + +The final example shows that multiple TCP targets can be specified. Exim will +randomly use one for each incoming email (i.e. it load balances them). Note +that only TCP targets may be used if specifying a list of scanners; a UNIX +socket cannot be mixed in with TCP targets. If one of the servers becomes +unavailable, Exim will try the remaining one(s) until it finds one that works. +When a clamd server becomes unreachable, Exim will log a message. Exim does +not keep track of scanner state between multiple messages, and the scanner +selection is random, so the message will get logged in the mainlog for each +email that the down scanner gets chosen first (message wrapped to be readable): +.code +2013-10-09 14:30:39 1VTumd-0000Y8-BQ malware acl condition: + clamd: connection to localhost, port 3310 failed + (Connection refused) +.endd + If the option is unset, the default is &_/tmp/clamd_&. Thanks to David Saez for contributing the code for this scanner. @@ -29015,9 +31200,13 @@ av_scanner = cmdline:\ .endd .vitem &%drweb%& .cindex "virus scanners" "DrWeb" -The DrWeb daemon scanner (&url(http://www.sald.com/)) interface takes one -argument, either a full path to a UNIX socket, or an IP address and port -separated by white space, as in these examples: +The DrWeb daemon scanner (&url(http://www.sald.com/)) interface +takes one option, +either a full path to a UNIX socket, +or host and port specifiers separated by white space. +The host may be a name or an IP address; the port is either a +single number or a pair of numbers with a dash between. +For example: .code av_scanner = drweb:/var/run/drwebd.sock av_scanner = drweb:192.168.2.20 31337 @@ -29025,6 +31214,17 @@ av_scanner = drweb:192.168.2.20 31337 If you omit the argument, the default path &_/usr/local/drweb/run/drwebd.sock_& is used. Thanks to Alex Miller for contributing the code for this scanner. +.vitem &%f-protd%& +.cindex "virus scanners" "f-protd" +The f-protd scanner is accessed via HTTP over TCP. +One argument is taken, being a space-separated hostname and port number +(or port-range). +For example: +.code +av_scanner = f-protd:localhost 10200-10204 +.endd +If you omit the argument, the default values show above are used. + .vitem &%fsecure%& .cindex "virus scanners" "F-Secure" The F-Secure daemon scanner (&url(http://www.f-secure.com)) takes one @@ -29059,6 +31259,24 @@ av_scanner = mksd:2 .endd You can safely omit this option (the default value is 1). +.vitem &%sock%& +.cindex "virus scanners" "simple socket-connected" +This is a general-purpose way of talking to simple scanner daemons +running on the local machine. +There are four options: +an address (which may be an IP address and port, or the path of a Unix socket), +a commandline to send (may include a single %s which will be replaced with +the path to the mail file to be scanned), +an RE to trigger on from the returned data, +an RE to extract malware_name from the returned data. +For example: +.code +av_scanner = sock:127.0.0.1 6001:%s:(SPAM|VIRUS):(.*)\$ +.endd +Default for the socket specifier is &_/tmp/malware.sock_&. +Default for the commandline is &_%s\n_&. +Both regular-expressions are required. + .vitem &%sophie%& .cindex "virus scanners" "Sophos and Sophie" Sophie is a daemon that uses Sophos' &%libsavi%& library to scan for viruses. @@ -29085,7 +31303,8 @@ which case each use of the &%malware%& condition causes a new scan of the message. The &%malware%& condition takes a right-hand argument that is expanded before -use. It can then be one of +use and taken as a list, slash-separated by default. +The first element can then be one of .ilist &"true"&, &"*"&, or &"1"&, in which case the message is scanned for viruses. @@ -29098,11 +31317,25 @@ the condition fails immediately. A regular expression, in which case the message is scanned for viruses. The condition succeeds if a virus is found and its name matches the regular expression. This allows you to take special actions on certain types of virus. +Note that &"/"& characters in the RE must be doubled due to the list-processing, +unless the separator is changed (in the usual way). .endlist -You can append &`/defer_ok`& to the &%malware%& condition to accept messages -even if there is a problem with the virus scanner. Otherwise, such a problem -causes the ACL to defer. +You can append a &`defer_ok`& element to the &%malware%& argument list to accept +messages even if there is a problem with the virus scanner. +Otherwise, such a problem causes the ACL to defer. + +You can append a &`tmo=`& element to the &%malware%& argument list to +specify a non-default timeout. The default is two minutes. +For example: +.code +malware = * / defer_ok / tmo=10s +.endd +A timeout causes the ACL to defer. + +.vindex "&$callout_address$&" +When a connection is made to the scanner the expansion variable &$callout_address$& +is set to record the actual address used. .vindex "&$malware_name$&" When a virus is found, the condition sets up an expansion variable called @@ -29146,14 +31379,20 @@ deny message = This message contains malware ($malware_name) .endd -.section "Scanning with SpamAssassin" "SECTscanspamass" +.section "Scanning with SpamAssassin and Rspamd" "SECTscanspamass" .cindex "content scanning" "for spam" .cindex "spam scanning" .cindex "SpamAssassin" +.cindex "Rspamd" The &%spam%& ACL condition calls SpamAssassin's &%spamd%& daemon to get a spam -score and a report for the message. You can get SpamAssassin at -&url(http://www.spamassassin.org), or, if you have a working Perl -installation, you can use CPAN by running: +score and a report for the message. +Support is also provided for Rspamd. + +For more information about installation and configuration of SpamAssassin or +Rspamd refer to their respective websites at +&url(http://spamassassin.apache.org) and &url(http://www.rspamd.com) + +SpamAssassin can be installed with CPAN by running: .code perl -MCPAN -e 'install Mail::SpamAssassin' .endd @@ -29162,42 +31401,96 @@ documentation to see how you can tweak it. The default installation should work nicely, however. .oindex "&%spamd_address%&" -After having installed and configured SpamAssassin, start the &%spamd%& daemon. -By default, it listens on 127.0.0.1, TCP port 783. If you use another host or -port for &%spamd%&, you must set the &%spamd_address%& option in the global -part of the Exim configuration as follows (example): +By default, SpamAssassin listens on 127.0.0.1, TCP port 783 and if you +intend to use an instance running on the local host you do not need to set +&%spamd_address%&. If you intend to use another host or port for SpamAssassin, +you must set the &%spamd_address%& option in the global part of the Exim +configuration as follows (example): .code spamd_address = 192.168.99.45 387 .endd -You do not need to set this option if you use the default. As of version 2.60, -&%spamd%& also supports communication over UNIX sockets. If you want to use -these, supply &%spamd_address%& with an absolute file name instead of a -address/port pair: + +To use Rspamd (which by default listens on all local addresses +on TCP port 11333) +you should add &%variant=rspamd%& after the address/port pair, for example: +.code +spamd_address = 127.0.0.1 11333 variant=rspamd +.endd + +As of version 2.60, &%SpamAssassin%& also supports communication over UNIX +sockets. If you want to us these, supply &%spamd_address%& with an absolute +file name instead of an address/port pair: .code spamd_address = /var/run/spamd_socket .endd You can have multiple &%spamd%& servers to improve scalability. These can reside on other hardware reachable over the network. To specify multiple &%spamd%& servers, put multiple address/port pairs in the &%spamd_address%& -option, separated with colons: +option, separated with colons (the separator can be changed in the usual way): .code spamd_address = 192.168.2.10 783 : \ 192.168.2.11 783 : \ 192.168.2.12 783 .endd -Up to 32 &%spamd%& servers are supported. The servers are queried in a random -fashion. When a server fails to respond to the connection attempt, all other +Up to 32 &%spamd%& servers are supported. +When a server fails to respond to the connection attempt, all other servers are tried until one succeeds. If no server responds, the &%spam%& condition defers. -&*Warning*&: It is not possible to use the UNIX socket connection method with -multiple &%spamd%& servers. +Unix and TCP socket specifications may be mixed in any order. +Each element of the list is a list itself, space-separated by default +and changeable in the usual way. + +For TCP socket specifications a host name or IP (v4 or v6, but +subject to list-separator quoting rules) address can be used, +and the port can be one or a dash-separated pair. +In the latter case, the range is tried in strict order. + +Elements after the first for Unix sockets, or second for TCP socket, +are options. +The supported options are: +.code +pri= Selection priority +weight= Selection bias +time=- Use only between these times of day +retry= Retry on connect fail +tmo= Connection time limit +variant=rspamd Use Rspamd rather than SpamAssassin protocol +.endd + +The &`pri`& option specifies a priority for the server within the list, +higher values being tried first. +The default priority is 1. + +The &`weight`& option specifies a selection bias. +Within a priority set +servers are queried in a random fashion, weighted by this value. +The default value for selection bias is 1. + +Time specifications for the &`time`& option are .. +in the local time zone; each element being one or more digits. +Either the seconds or both minutes and seconds, plus the leading &`.`& +characters, may be omitted and will be taken as zero. + +Timeout specifications for the &`retry`& and &`tmo`& options +are the usual Exim time interval standard, e.g. &`20s`& or &`1m`&. + +The &`tmo`& option specifies an overall timeout for communication. +The default value is two minutes. + +The &`retry`& option specifies a time after which a single retry for +a failed connect is made. +The default is to not retry. The &%spamd_address%& variable is expanded before use if it starts with a dollar sign. In this case, the expansion may return a string that is used as the list so that multiple spamd servers can be the result of an expansion. +.vindex "&$callout_address$&" +When a connection is made to the server the expansion variable &$callout_address$& +is set to record the actual address used. + .section "Calling SpamAssassin from an Exim ACL" "SECID206" Here is a simple example of the use of the &%spam%& condition in a DATA ACL: .code @@ -29208,14 +31501,21 @@ The right-hand side of the &%spam%& condition specifies a name. This is relevant if you have set up multiple SpamAssassin profiles. If you do not want to scan using a specific profile, but rather use the SpamAssassin system-wide default profile, you can scan for an unknown name, or simply use &"nobody"&. -However, you must put something on the right-hand side. +Rspamd does not use this setting. However, you must put something on the +right-hand side. The name allows you to use per-domain or per-user antispam profiles in principle, but this is not straightforward in practice, because a message may have multiple recipients, not necessarily all in the same domain. Because the -&%spam%& condition has to be called from a DATA ACL in order to be able to +&%spam%& condition has to be called from a DATA-time ACL in order to be able to read the contents of the message, the variables &$local_part$& and &$domain$& are not set. +Careful enforcement of single-recipient messages +(e.g. by responding with defer in the recipient ACL for all recipients +after the first), +or the use of PRDR, +.cindex "PRDR" "use for per-user SpamAssassin profiles" +are needed to use this feature. The right-hand side of the &%spam%& condition is expanded before being used, so you can put lookups or conditions there. When the right-hand side evaluates to @@ -29239,7 +31539,9 @@ it always return &"true"& by appending &`:true`& to the username. .cindex "spam scanning" "returned variables" When the &%spam%& condition is run, it sets up a number of expansion -variables. These variables are saved with the received message, thus they are +variables. +Except for &$spam_report$&, +these variables are saved with the received message so are available for use at delivery time. .vlist @@ -29257,11 +31559,19 @@ The integer value is useful for numeric comparisons in conditions. A string consisting of a number of &"+"& or &"-"& characters, representing the integer part of the spam score value. A spam score of 4.4 would have a &$spam_bar$& value of &"++++"&. This is useful for inclusion in warning -headers, since MUAs can match on such strings. +headers, since MUAs can match on such strings. The maximum length of the +spam bar is 50 characters. .vitem &$spam_report$& A multiline text table, containing the full SpamAssassin report for the message. Useful for inclusion in headers or reject messages. +This variable is only usable in a DATA-time ACL. + +.vitem &$spam_action$& +For SpamAssassin either 'reject' or 'no action' depending on the +spam score versus threshold. +For Rspamd, the recommended action. + .endlist The &%spam%& condition caches its results unless expansion in @@ -29447,7 +31757,10 @@ containing the decoded data. This is perhaps the most important of the MIME variables. It contains a proposed filename for an attachment, if one was found in either the &'Content-Type:'& or &'Content-Disposition:'& headers. The filename will be -RFC2047 decoded, but no additional sanity checks are done. If no filename was +RFC2047 +or RFC2231 +decoded, but no additional sanity checks are done. + If no filename was found, this variable contains the empty string. .vitem &$mime_is_coverletter$& @@ -29536,6 +31849,8 @@ deny message = contains blacklisted regex ($regex_match_string) The conditions returns true if any one of the regular expressions matches. The &$regex_match_string$& expansion variable is then set up and contains the matching regular expression. +The expansion variables &$regex1$& &$regex2$& etc +are set to any substrings captured by the regular expression. &*Warning*&: With large messages, these conditions can be fairly CPU-intensive. @@ -31181,7 +33496,7 @@ they do not affect the values of the variables that refer to header lines. the transport cannot refer to the modified header lines, because such expansions all occur before the message is actually transported. -For both routers and transports, the result of expanding a &%headers_add%& +For both routers and transports, the argument of a &%headers_add%& option must be in the form of one or more RFC 2822 header lines, separated by newlines (coded as &"\n"&). For example: .code @@ -31190,15 +33505,28 @@ headers_add = X-added-header: added by $primary_hostname\n\ .endd Exim does not check the syntax of these added header lines. -The result of expanding &%headers_remove%& must consist of a colon-separated +Multiple &%headers_add%& options for a single router or transport can be +specified; the values will append to a single list of header lines. +Each header-line is separately expanded. + +The argument of a &%headers_remove%& option must consist of a colon-separated list of header names. This is confusing, because header names themselves are often terminated by colons. In this case, the colons are the list separators, not part of the names. For example: .code headers_remove = return-receipt-to:acknowledge-to .endd -When &%headers_add%& or &%headers_remove%& is specified on a router, its value -is expanded at routing time, and then associated with all addresses that are + +Multiple &%headers_remove%& options for a single router or transport can be +specified; the arguments will append to a single header-names list. +Each item is separately expanded. +Note that colons in complex expansions which are used to +form all or part of a &%headers_remove%& list +will act as list separators. + +When &%headers_add%& or &%headers_remove%& is specified on a router, +items are expanded at routing time, +and then associated with all addresses that are accepted by that router, and also with any new addresses that it generates. If an address passes through several routers as a result of aliasing or forwarding, the changes are cumulative. @@ -31435,6 +33763,8 @@ required for the transaction. If the remote server advertises support for the STARTTLS command, and Exim was built to support TLS encryption, it tries to start a TLS session unless the server matches &%hosts_avoid_tls%&. See chapter &<>& for more details. +Either a match in that or &%hosts_verify_avoid_tls%& apply when the transport +is called for verification. If the remote server advertises support for the AUTH command, Exim scans the authenticators configuration for any suitable client settings, as described @@ -31789,13 +34119,20 @@ specific badly-behaved hosts that you have to live with. When Exim receives a VRFY or EXPN command on a TCP/IP connection, it runs the ACL specified by &%acl_smtp_vrfy%& or &%acl_smtp_expn%& (as appropriate) in order to decide whether the command should be accepted or not. -If no ACL is defined, the command is rejected. +.new .cindex "VRFY" "processing" +When no ACL is defined for VRFY, or if it rejects without +setting an explicit response code, the command is accepted +(with a 252 SMTP response code) +in order to support awkward clients that do a VRFY before every RCPT. +.wen When VRFY is accepted, it runs exactly the same code as when Exim is -called with the &%-bv%& option. +called with the &%-bv%& option, and returns 250/451/550 +SMTP response codes. .cindex "EXPN" "processing" +If no ACL for EXPN is defined, the command is rejected. When EXPN is accepted, a single-level expansion of the address is done. EXPN is treated as an &"address test"& (similar to the &%-bt%& option) rather than a verification (the &%-bv%& option). If an unqualified local part is given @@ -32030,13 +34367,8 @@ failing addresses with their error messages. The third item is used to introduce any text from pipe transports that is to be returned to the sender. It is omitted if there is no such text. .next -The fourth item is used to introduce the copy of the message that is returned -as part of the error report. -.next -The fifth item is added after the fourth one if the returned message is -truncated because it is bigger than &%return_size_limit%&. -.next -The sixth item is added after the copy of the original message. +The fourth, fifth and sixth items will be ignored and may be empty. +The fields exist for back-compatibility .endlist The default state (&%bounce_message_file%& unset) is equivalent to the @@ -32873,8 +35205,9 @@ equivalent to the setting: .code log_file_path = $spool_directory/log/%slog .endd -If you do not specify anything at build time or run time, that is where the -logs are written. +If you do not specify anything at build time or run time, +or if you unset the option at run time (i.e. &`log_file_path = `&), +that is where the logs are written. A log file path may also contain &`%D`& or &`%M`& if datestamped log file names are in use &-- see section &<>& below. @@ -33058,6 +35391,7 @@ timestamp. The flags are: &`<=`& message arrival &`=>`& normal message delivery &`->`& additional address in same delivery +&`>>`& cutthrough message delivery &`*>`& delivery suppressed by &%-N%& &`**`& delivery failed; address bounced &`==`& delivery deferred; temporary problem @@ -33118,6 +35452,7 @@ extensions (ESMTP), encryption, or authentication were used. If the SMTP session was encrypted, there is an additional X field that records the cipher suite that was used. +.cindex log protocol The protocol is set to &"esmtpsa"& or &"esmtpa"& for messages received from hosts that have authenticated themselves using the SMTP AUTH command. The first value is used when the SMTP connection was encrypted (&"secure"&). In this case @@ -33142,7 +35477,7 @@ data when a message is received. See section &<>& below. .cindex "log" "delivery line" The format of the single-line entry in the main log that is written for every delivery is shown in one of the examples below, for local and remote -deliveries, respectively. Each example has been split into two lines in order +deliveries, respectively. Each example has been split into multiple lines in order to fit it on the page: .code 2002-10-31 08:59:13 16ZCW1-0005MB-00 => marv @@ -33157,6 +35492,11 @@ intermediate address(es) exist between the original and the final address, the last of these is given in parentheses after the final address. The R and T fields record the router and transport that were used to process the address. +If SMTP AUTH was used for the delivery there is an additional item A= +followed by the name of the authenticator that was used. +If an authenticated identification was set up by the authenticator's &%client_set_id%& +option, this is logged too, separated by a colon from the authenticator name. + If a shadow transport was run after a successful local delivery, the log line for the successful delivery has an item added on the end, of the form .display @@ -33172,6 +35512,12 @@ flagged with &`->`& instead of &`=>`&. When two or more messages are delivered down a single SMTP connection, an asterisk follows the IP address in the log lines for the second and subsequent messages. +.cindex "delivery" "cutthrough; logging" +.cindex "cutthrough" "logging" +When delivery is done in cutthrough mode it is flagged with &`>>`& and the log +line precedes the reception line, since cutthrough waits for a possible +rejection from the destination in case it can reject the sourced item. + The generation of a reply message by a filter file gets logged as a &"delivery"& to the addressee, preceded by &">"&. @@ -33264,7 +35610,7 @@ at the end of its processing. A summary of the field identifiers that are used in log lines is shown in the following table: .display -&`A `& authenticator name (and optional id) +&`A `& authenticator name (and optional id and sender) &`C `& SMTP confirmation on delivery &` `& command list for &"no mail in SMTP session"& &`CV `& certificate verification status @@ -33277,11 +35623,13 @@ the following table: &`id `& message id for incoming message &`P `& on &`<=`& lines: protocol used &` `& on &`=>`& and &`**`& lines: return path +&`PRX `& on &'<='& and&`=>`& lines: proxy address &`QT `& on &`=>`& lines: time spent on queue so far &` `& on &"Completed"& lines: time spent on queue &`R `& on &`<=`& lines: reference for local bounce &` `& on &`=>`& &`**`& and &`==`& lines: router name -&`S `& size of message +&`S `& size of message in bytes +&`SNI `& server name indication from TLS client hello &`ST `& shadow transport name &`T `& on &`<=`& lines: message subject (topic) &` `& on &`=>`& &`**`& and &`==`& lines: transport name @@ -33348,6 +35696,7 @@ log_selector = +arguments -retry_defer The list of optional log items is in the following table, with the default selection marked by asterisks: .display +&` 8bitmime `& received 8BITMIME status &`*acl_warn_skipped `& skipped &%warn%& statement in ACL &` address_rewrite `& address rewriting &` all_parents `& all parents in => lines @@ -33360,14 +35709,20 @@ selection marked by asterisks: &`*etrn `& ETRN commands &`*host_lookup_failed `& as it says &` ident_timeout `& timeout for ident connection -&` incoming_interface `& incoming interface on <= lines -&` incoming_port `& incoming port on <= lines +&` incoming_interface `& local interface on <= and => lines +&` incoming_port `& remote port on <= lines &`*lost_incoming_connection `& as it says (includes timeouts) +.new +&` outgoing_interface `& local interface on => lines +.wen &` outgoing_port `& add remote port to => lines &`*queue_run `& start and end queue runs &` queue_time `& time on queue for one recipient &` queue_time_overall `& time on queue for whole message &` pid `& Exim process id +.new +&` proxy `& proxy address on <= and => lines +.wen &` received_recipients `& recipients on <= lines &` received_sender `& sender on <= lines &`*rejected_header `& header contents on reject log @@ -33377,14 +35732,15 @@ selection marked by asterisks: &`*sender_verify_fail `& sender verification failures &`*size_reject `& rejection because too big &`*skip_delivery `& delivery skipped in a queue run -&` smtp_confirmation `& SMTP confirmation on => lines -&` smtp_connection `& SMTP connections +&`*smtp_confirmation `& SMTP confirmation on => lines +&` smtp_connection `& incoming SMTP connections &` smtp_incomplete_transaction`& incomplete SMTP transactions +&` smtp_mailauth `& AUTH argument to MAIL commands &` smtp_no_mail `& session with no MAIL commands &` smtp_protocol_error `& SMTP protocol errors &` smtp_syntax_error `& SMTP syntax errors &` subject `& contents of &'Subject:'& on <= lines -&` tls_certificate_verified `& certificate verification status +&`*tls_certificate_verified `& certificate verification status &`*tls_cipher `& TLS cipher suite on <= and => lines &` tls_peerdn `& TLS peer DN on <= and => lines &` tls_sni `& TLS SNI on <= lines @@ -33392,9 +35748,20 @@ selection marked by asterisks: &` all `& all of the above .endd +See also the &%slow_lookup_log%& main configuration option, +section &<>& + More details on each of these items follows: .ilist +.cindex "8BITMIME" +.cindex "log" "8BITMIME" +&%8bitmime%&: This causes Exim to log any 8BITMIME status of received messages, +which may help in tracking down interoperability issues with ancient MTAs +that are not 8bit clean. This is added to the &"<="& line, tagged with +&`M8S=`& and a value of &`0`&, &`7`& or &`8`&, corresponding to "not given", +&`7BIT`& and &`8BITMIME`& respectively. +.next .cindex "&%warn%& ACL verb" "log when skipping" &%acl_warn_skipped%&: When an ACL &%warn%& statement is skipped because one of its conditions cannot be evaluated, a log line to this effect is written if @@ -33469,12 +35836,29 @@ routing email addresses, but it does apply to &"byname"& lookups. client's ident port times out. .next .cindex "log" "incoming interface" +.cindex "log" "local interface" +.cindex "log" "local address and port" +.cindex "TCP/IP" "logging local address and port" .cindex "interface" "logging" &%incoming_interface%&: The interface on which a message was received is added to the &"<="& line as an IP address in square brackets, tagged by I= and followed by a colon and the port number. The local interface and port are also -added to other SMTP log lines, for example &"SMTP connection from"&, and to -rejection lines. +added to other SMTP log lines, for example &"SMTP connection from"&, to +rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines. +.new +The latter can be disabled by turning off the &%outgoing_interface%& option. +.wen +.next +.new +.cindex log "incoming proxy address" +.cindex proxy "logging proxy address" +.cindex "TCP/IP" "logging proxy address" +&%proxy%&: The internal (closest to the system running Exim) IP address +of the proxy, tagged by PRX=, on the &"<="& line for a message accepted +on a proxied connection +or the &"=>"& line for a message delivered on a proxied connection.. +See &<>& for more information. +.wen .next .cindex "log" "incoming remote port" .cindex "port" "logging remote" @@ -33492,13 +35876,30 @@ important with the widening use of NAT (see RFC 2505). &%lost_incoming_connection%&: A log line is written when an incoming SMTP connection is unexpectedly dropped. .next +.cindex "log" "outgoing interface" +.cindex "log" "local interface" +.cindex "log" "local address and port" +.cindex "TCP/IP" "logging local address and port" +.cindex "interface" "logging" +.new +&%outgoing_interface%&: If &%incoming_interface%& is turned on, then the +interface on which a message was sent is added to delivery lines as an I= tag +followed by IP address in square brackets. You can disable this by turning +off the &%outgoing_interface%& option. +.wen +.next .cindex "log" "outgoing remote port" .cindex "port" "logging outgoint remote" .cindex "TCP/IP" "logging ougtoing remote port" &%outgoing_port%&: The remote port number is added to delivery log lines (those -containing => tags) following the IP address. This option is not included in -the default setting, because for most ordinary configurations, the remote port -number is always 25 (the SMTP port). +containing => tags) following the IP address. +.new +The local port is also added if &%incoming_interface%& and +&%outgoing_interface%& are both enabled. +.wen +This option is not included in the default setting, because for most ordinary +configurations, the remote port number is always 25 (the SMTP port), and the +local port is a random ephemeral port. .next .cindex "log" "process ids in" .cindex "pid (process id)" "in log lines" @@ -33581,14 +35982,15 @@ The message that is written is &"spool file is locked"&. .next .cindex "log" "smtp confirmation" .cindex "SMTP" "logging confirmation" -&%smtp_confirmation%&: The response to the final &"."& in the SMTP dialogue for +.cindex "LMTP" "logging confirmation" +&%smtp_confirmation%&: The response to the final &"."& in the SMTP or LMTP dialogue for outgoing messages is added to delivery log lines in the form &`C=`&<&'text'&>. A number of MTAs (including Exim) return an identifying string in this response. .next .cindex "log" "SMTP connections" .cindex "SMTP" "logging connections" -&%smtp_connection%&: A log line is written whenever an SMTP connection is +&%smtp_connection%&: A log line is written whenever an incoming SMTP connection is established or closed, unless the connection is from a host that matches &%hosts_connection_nolog%&. (In contrast, &%lost_incoming_connection%& applies only when the closure is unexpected.) This applies to connections from local @@ -33637,9 +36039,14 @@ C=EHLO,QUIT shows that the client issued QUIT straight after EHLO. If there were fewer than 20 commands, they are all listed. If there were more than 20 commands, the last 20 are listed, preceded by &"..."&. However, with the default -setting of 10 for &%smtp_accep_max_nonmail%&, the connection will in any case +setting of 10 for &%smtp_accept_max_nonmail%&, the connection will in any case have been aborted before 20 non-mail commands are processed. .next +&%smtp_mailauth%&: A third subfield with the authenticated sender, +colon-separated, is appended to the A= item for a message arrival or delivery +log line, if an AUTH argument to the SMTP MAIL command (see &<>&) +was accepted or used. +.next .cindex "log" "SMTP protocol error" .cindex "SMTP" "logging protocol error" &%smtp_protocol_error%&: A log line is written for every SMTP protocol error @@ -33805,20 +36212,26 @@ This utility is a Perl script contributed by Matt Hubbard. It runs .code exim -bpu .endd -to obtain a queue listing with undelivered recipients only, and then greps the -output to select messages that match given criteria. The following selection -options are available: +or (in case &*-a*& switch is specified) +.code +exim -bp +.endd +The &*-C*& option is used to specify an alternate &_exim.conf_& which might +contain alternate exim configuration the queue management might be using. + +to obtain a queue listing, and then greps the output to select messages +that match given criteria. The following selection options are available: .vlist .vitem &*-f*&&~<&'regex'&> -Match the sender address. The field that is tested is enclosed in angle -brackets, so you can test for bounce messages with +Match the sender address using a case-insensitive search. The field that is +tested is enclosed in angle brackets, so you can test for bounce messages with .code exiqgrep -f '^<>$' .endd .vitem &*-r*&&~<&'regex'&> -Match a recipient address. The field that is tested is not enclosed in angle -brackets. +Match a recipient address using a case-insensitive search. The field that is +tested is not enclosed in angle brackets. .vitem &*-s*&&~<&'regex'&> Match against the size field. @@ -33854,6 +36267,9 @@ Brief format &-- one line per message. .vitem &*-R*& Display messages in reverse order. + +.vitem &*-a*& +Include delivered recipients in queue listing. .endlist There is one more option, &%-h%&, which outputs a list of options. @@ -33909,7 +36325,7 @@ The input files can be in Exim log format or syslog format. If a matching log line is not associated with a specific message, it is included in &'exigrep'&'s output without any additional lines. The usage is: .display -&`exigrep [-t<`&&'n'&&`>] [-I] [-l] [-v] <`&&'pattern'&&`> [<`&&'log file'&&`>] ...`& +&`exigrep [-t<`&&'n'&&`>] [-I] [-l] [-M] [-v] <`&&'pattern'&&`> [<`&&'log file'&&`>] ...`& .endd If no log file names are given on the command line, the standard input is read. @@ -33930,9 +36346,24 @@ regular expression. The &%-v%& option inverts the matching condition. That is, a line is selected if it does &'not'& match the pattern. +The &%-M%& options means &"related messages"&. &'exigrep'& will show messages +that are generated as a result/response to a message that &'exigrep'& matched +normally. + +Example of &%-M%&: +user_a sends a message to user_b, which generates a bounce back to user_b. If +&'exigrep'& is used to search for &"user_a"&, only the first message will be +displayed. But if &'exigrep'& is used to search for &"user_b"&, the first and +the second (bounce) message will be displayed. Using &%-M%& with &'exigrep'& +when searching for &"user_a"& will show both messages since the bounce is +&"related"& to or a &"result"& of the first message that was found by the +search term. + If the location of a &'zcat'& command is known from the definition of ZCAT_COMMAND in &_Local/Makefile_&, &'exigrep'& automatically passes any file whose name ends in COMPRESS_SUFFIX through &'zcat'& as it searches it. +If the ZCAT_COMMAND is not executable, &'exigrep'& tries to use +autodetection of some well known compression extensions. .section "Selecting messages by various criteria (exipick)" "SECTexipick" @@ -34212,6 +36643,9 @@ Serializing ETRN runs (when &%smtp_etrn_serialize%& is set) .next Serializing delivery to a specific host (when &%serialize_hosts%& is set in an &(smtp)& transport) +.next +Limiting the concurrency of specific transports (when &%max_parallel%& is set +in a transport) .endlist @@ -35042,6 +37476,85 @@ are given in chapter &<>&. +.section "Running local commands" "SECTsecconslocalcmds" +.cindex "security" "local commands" +.cindex "security" "command injection attacks" +There are a number of ways in which an administrator can configure Exim to run +commands based upon received, untrustworthy, data. Further, in some +configurations a user who can control a &_.forward_& file can also arrange to +run commands. Configuration to check includes, but is not limited to: + +.ilist +Use of &%use_shell%& in the pipe transport: various forms of shell command +injection may be possible with this option present. It is dangerous and should +be used only with considerable caution. Consider constraints which whitelist +allowed characters in a variable which is to be used in a pipe transport that +has &%use_shell%& enabled. +.next +A number of options such as &%forbid_filter_run%&, &%forbid_filter_perl%&, +&%forbid_filter_dlfunc%& and so forth which restrict facilities available to +&_.forward_& files in a redirect router. If Exim is running on a central mail +hub to which ordinary users do not have shell access, but home directories are +NFS mounted (for instance) then administrators should review the list of these +forbid options available, and should bear in mind that the options that may +need forbidding can change as new features are added between releases. +.next +The &%${run...}%& expansion item does not use a shell by default, but +administrators can configure use of &_/bin/sh_& as part of the command. +Such invocations should be viewed with prejudicial suspicion. +.next +Administrators who use embedded Perl are advised to explore how Perl's +taint checking might apply to their usage. +.next +Use of &%${expand...}%& is somewhat analogous to shell's eval builtin and +administrators are well advised to view its use with suspicion, in case (for +instance) it allows a local-part to contain embedded Exim directives. +.next +Use of &%${match_local_part...}%& and friends becomes more dangerous if +Exim was built with EXPAND_LISTMATCH_RHS defined: the second string in +each can reference arbitrary lists and files, rather than just being a list +of opaque strings. +The EXPAND_LISTMATCH_RHS option was added and set false by default because of +real-world security vulnerabilities caused by its use with untrustworthy data +injected in, for SQL injection attacks. +Consider the use of the &%inlisti%& expansion condition instead. +.endlist + + + + +.section "Trust in configuration data" "SECTsecconfdata" +.cindex "security" "data sources" +.cindex "security" "regular expressions" +.cindex "regular expressions" "security" +.cindex "PCRE" "security" +If configuration data for Exim can come from untrustworthy sources, there +are some issues to be aware of: + +.ilist +Use of &%${expand...}%& may provide a path for shell injection attacks. +.next +Letting untrusted data provide a regular expression is unwise. +.next +Using &%${match...}%& to apply a fixed regular expression against untrusted +data may result in pathological behaviour within PCRE. Be aware of what +"backtracking" means and consider options for being more strict with a regular +expression. Avenues to explore include limiting what can match (avoiding &`.`& +when &`[a-z0-9]`& or other character class will do), use of atomic grouping and +possessive quantifiers or just not using regular expressions against untrusted +data. +.next +It can be important to correctly use &%${quote:...}%&, +&%${quote_local_part:...}%& and &%${quote_%&<&'lookup-type'&>&%:...}%& expansion +items to ensure that data is correctly constructed. +.next +Some lookups might return multiple results, even though normal usage is only +expected to yield one result. +.endlist + + + + .section "IPv4 source routing" "SECID272" .cindex "source routing" "in IP packets" .cindex "IP source routing" @@ -35499,7 +38012,7 @@ unqualified domain &'foundation'&. . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.chapter "Support for DKIM (DomainKeys Identified Mail)" "CHID12" &&& +.chapter "Support for DKIM (DomainKeys Identified Mail)" "CHAPdkim" &&& "DKIM Support" .cindex "DKIM" @@ -35508,13 +38021,17 @@ linked to a domain which that entity controls. It permits reputation to be tracked on a per-domain basis, rather than merely upon source IP address. DKIM is documented in RFC 4871. -Since version 4.70, DKIM support is compiled into Exim by default. It can be -disabled by setting DISABLE_DKIM=yes in Local/Makefile. +.new +DKIM support is compiled into Exim by default if TLS support is present. +.wen +It can be disabled by setting DISABLE_DKIM=yes in &_Local/Makefile_&. Exim's DKIM implementation allows to .olist Sign outgoing messages: This function is implemented in the SMTP transport. -It can co-exist with all other Exim features, including transport filters. +It can co-exist with all other Exim features +(including transport filters) +except cutthrough delivery. .next Verify signatures in incoming messages: This is implemented by an additional ACL (acl_smtp_dkim), which can be called several times per message, with @@ -35542,7 +38059,7 @@ where you accept mail from relay sources (internal hosts or authenticated senders). -.section "Signing outgoing messages" "SECID513" +.section "Signing outgoing messages" "SECDKIMSIGN" .cindex "DKIM" "signing" Signing is implemented by setting private options on the SMTP transport. @@ -35557,7 +38074,7 @@ option is put into the &%$dkim_domain%& expansion variable. MANDATORY: This sets the key selector string. You can use the &%$dkim_domain%& expansion variable to look up a matching selector. The result is put in the expansion -variable &%$dkim_selector%& which should be used in the &%dkim_private_key%& +variable &%$dkim_selector%& which may be used in the &%dkim_private_key%& option along with &%$dkim_domain%&. .option dkim_private_key smtp string&!! unset @@ -35605,6 +38122,10 @@ used. Verification of DKIM signatures in incoming email is implemented via the &%acl_smtp_dkim%& ACL. By default, this ACL is called once for each syntactically(!) correct signature in the incoming message. +A missing ACL definition defaults to accept. +If any ACL call does not accept, the message is not accepted. +If a cutthrough delivery was in progress for the message it is +summarily dropped (having wasted the transmission effort). To evaluate the signature in the ACL a large number of expansion variables containing the signature status and its details are set up during the @@ -35666,7 +38187,7 @@ available in &%$dkim_verify_reason%&. &%pass%&: The signature passed verification. It is valid. .endlist .vitem &%$dkim_verify_reason%& -A string giving a litte bit more detail when &%$dkim_verify_status%& is either +A string giving a little bit more detail when &%$dkim_verify_status%& is either "fail" or "invalid". One of .ilist &%pubkey_unavailable%& (when &%$dkim_verify_status%&="invalid"): The public @@ -35719,7 +38240,7 @@ integer size comparisons against this value. A colon-separated list of names of headers included in the signature. .vitem &%$dkim_key_testing%& "1" if the key record has the "testing" flag set, "0" if not. -.vitem &%$nosubdomains%& +.vitem &%$dkim_key_nosubdomains%& "1" if the key record forbids subdomaining, "0" otherwise. .vitem &%$dkim_key_srvtype%& Service type (tag s=) from the key record. Defaults to "*" if not specified @@ -35729,6 +38250,8 @@ Key granularity (tag g=) from the key record. Defaults to "*" if not specified in the key record. .vitem &%$dkim_key_notes%& Notes from the key record (tag n=). +.vitem &%$dkim_key_length%& +Number of bits in the key. .endlist In addition, two ACL conditions are provided: @@ -35750,7 +38273,7 @@ warn log_message = GMail sender without DKIM signature .vitem &%dkim_status%& ACL condition that checks a colon-separated list of possible DKIM verification -results agains the actual result of verification. This is typically used +results against the actual result of verification. This is typically used to restrict an ACL verb to a list of verification outcomes, for example: .code @@ -35768,6 +38291,390 @@ for more information of what they mean. . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// +.chapter "Proxies" "CHAPproxies" &&& + "Proxy support" +.cindex "proxy support" +.cindex "proxy" "access via" + +.new +A proxy is an intermediate system through which communication is passed. +Proxies may provide a security, availability or load-distribution function. + + +.section "Inbound proxies" SECTproxyInbound +.cindex proxy inbound +.cindex proxy "server side" +.cindex proxy "Proxy protocol" +.cindex "Proxy protocol" proxy + +Exim has support for receiving inbound SMTP connections via a proxy +that uses &"Proxy Protocol"& to speak to it. +To include this support, include &"SUPPORT_PROXY=yes"& +in Local/Makefile. + +It was built on specifications from: +http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt +That URL was revised in May 2014 to version 2 spec: +http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e + +The purpose of this facility is so that an application load balancer, +such as HAProxy, can sit in front of several Exim servers +to distribute load. +Exim uses the local protocol communication with the proxy to obtain +the remote SMTP system IP address and port information. +There is no logging if a host passes or +fails Proxy Protocol negotiation, but it can easily be determined and +recorded in an ACL (example is below). + +Use of a proxy is enabled by setting the &%hosts_proxy%& +main configuration option to a hostlist; connections from these +hosts will use Proxy Protocol. + +The following expansion variables are usable +(&"internal"& and &"external"& here refer to the interfaces +of the proxy): +.display +&'proxy_host_address '& internal IP address of the proxy +&'proxy_host_port '& internal TCP port of the proxy +&'proxy_target_address '& external IP address of the proxy +&'proxy_target_port '& external TCP port of the proxy +&'proxy_session '& boolean: SMTP connection via proxy +.endd +If &$proxy_session$& is set but &$proxy_host_address$& is empty +there was a protocol error. + +Since the real connections are all coming from the proxy, and the +per host connection tracking is done before Proxy Protocol is +evaluated, &%smtp_accept_max_per_host%& must be set high enough to +handle all of the parallel volume you expect per inbound proxy. +With the option set so high, you lose the ability +to protect your server from many connections from one IP. +In order to prevent your server from overload, you +need to add a per connection ratelimit to your connect ACL. +A possible solution is: +.display + # Set max number of connections per host + LIMIT = 5 + # Or do some kind of IP lookup in a flat file or database + # LIMIT = ${lookup{$sender_host_address}iplsearch{/etc/exim/proxy_limits}} + + defer message = Too many connections from this IP right now + ratelimit = LIMIT / 5s / per_conn / strict +.endd + + + +.section "Outbound proxies" SECTproxySOCKS +.cindex proxy outbound +.cindex proxy "client side" +.cindex proxy SOCKS +.cindex SOCKS proxy +Exim has support for sending outbound SMTP via a proxy +using a protocol called SOCKS5 (defined by RFC1928). +The support can be optionally included by defining SUPPORT_SOCKS=yes in +Local/Makefile. + +Use of a proxy is enabled by setting the &%socks_proxy%& option +on an smtp transport. +The option value is expanded and should then be a list +(colon-separated by default) of proxy specifiers. +Each proxy specifier is a list +(space-separated by default) where the initial element +is an IP address and any subsequent elements are options. + +Options are a string =. +The list of options is in the following table: +.display +&'auth '& authentication method +&'name '& authentication username +&'pass '& authentication password +&'port '& tcp port +&'tmo '& connection timeout +&'pri '& priority +&'weight '& selection bias +.endd + +More details on each of these options follows: + +.ilist +.cindex authentication "to proxy" +.cindex proxy authentication +&%auth%&: Either &"none"& (default) or &"name"&. +Using &"name"& selects username/password authentication per RFC 1929 +for access to the proxy. +Default is &"none"&. +.next +&%name%&: sets the username for the &"name"& authentication method. +Default is empty. +.next +&%pass%&: sets the password for the &"name"& authentication method. +Default is empty. +.next +&%port%&: the TCP port number to use for the connection to the proxy. +Default is 1080. +.next +&%tmo%&: sets a connection timeout in seconds for this proxy. +Default is 5. +.next +&%pri%&: specifies a priority for the proxy within the list, +higher values being tried first. +The default priority is 1. +.next +&%weight%&: specifies a selection bias. +Within a priority set servers are queried in a random fashion, +weighted by this value. +The default value for selection bias is 1. +.endlist + +Proxies from the list are tried according to their priority +and weight settings until one responds. The timeout for the +overall connection applies to the set of proxied attempts. + +.section Logging SECTproxyLog +To log the (local) IP of a proxy in the incoming or delivery logline, +add &"+proxy"& to the &%log_selector%& option. +This will add a component tagged with &"PRX="& to the line. +.wen + +. //////////////////////////////////////////////////////////////////////////// +. //////////////////////////////////////////////////////////////////////////// + +.chapter "Internationalisation" "CHAPi18n" &&& + "Internationalisation"" +.cindex internationalisation "email address" +.cindex EAI +.cindex i18n +.cindex UTF-8 "mail name handling" + +.new +Exim has support for Internationalised mail names. +To include this it must be built with SUPPORT_I18N and the libidn library. +Standards supported are RFCs 2060, 5890, 6530 and 6533. + +.section "MTA operations" SECTi18nMTA +.cindex SMTPUTF8 "ESMTP option" +The main configuration option &%smtputf8_advertise_hosts%& specifies +a host list. If this matches the sending host and +accept_8bitmime is true (the default) then the ESMTP option +SMTPUTF8 will be advertised. + +If the sender specifies the SMTPUTF8 option on a MAIL command +international handling for the message is enabled and +the expansion variable &$message_smtputf8$& will have value TRUE. + +The option &%allow_utf8_domains%& is set to true for this +message. All DNS lookups are converted to a-label form +whatever the setting of &%allow_utf8_domains%& +when Exim is built with SUPPORT_I18N. + +Both localparts and domain are maintained as the original +UTF-8 form internally; any comparison or regular-expression use will +require appropriate care. Filenames created, eg. by +the appendfile transport, will have UTF-8 names. + +HELO names sent by the smtp transport will have any UTF-8 +components expanded to a-label form, +and any certificate name checks will be done using the a-label +form of the name. + +.cindex log protocol +.cindex SMTPUTF8 logging +Log lines and Received-by: header lines will acquire a "utf8" +prefix on the protocol element, eg. utf8esmtp. + +The following expansion operator can be used: +.code +${utf8_domain_to_alabel:str} +${utf8_domain_from_alabel:str} +${utf8_localpart_to_alabel:str} +${utf8_localpart_from_alabel:str} +.endd + +ACLs may use the following modifier: +.display +control = utf8_downconvert +control = utf8_downconvert/ +.endd +This sets a flag requiring that addresses are converted to +a-label form before smtp delivery, for use in a +Message Submission Agent context. +If a value is appended it may be: +.display +&`1 `& (default) mandatory downconversion +&`0 `& no downconversion +&`-1 `& if SMTPUTF8 not supported by destination host +.endd + +If mua_wrapper is set, the utf8_downconvert control +is initially set to -1. + + +There is no explicit support for VRFY and EXPN. +Configurations supporting these should inspect +&$smtp_command_argument$& for an SMTPUTF8 argument. + +There is no support for LMTP on Unix sockets. +Using the "lmtp" protocol option on an smtp transport, +for LMTP over TCP, should work as expected. + +There is no support for DSN unitext handling, +and no provision for converting logging from or to UTF-8. + + + +.section "MDA operations" SECTi18nMDA +To aid in constructing names suitable for IMAP folders +the following expansion operator can be used: +.code +${imapfolder {} {} {}} +.endd + +The string is converted from the charset specified by +the "headers charset" command (in a filter file) +or &%headers_charset%& main configuration option (otherwise), +to the +modified UTF-7 encoding specified by RFC 2060, +with the following exception: All occurences of +(which has to be a single character) +are replaced with periods ("."), and all periods and slashes that are not + and are not in the string are BASE64 encoded. + +The third argument can be omitted, defaulting to an empty string. +The second argument can be omitted, defaulting to "/". + +This is the encoding used by Courier for Maildir names on disk, and followed +by many other IMAP servers. + +Examples: +.display +&`${imapfolder {Foo/Bar}} `& yields &`Foo.Bar`& +&`${imapfolder {Foo/Bar}{.}{/}} `& yields &`Foo&&AC8-Bar`& +&`${imapfolder {RäksmörgÃ¥s}} `& yields &`R&&AOQ-ksm&&APY-rg&&AOU-s`& +.endd + +Note that the source charset setting is vital, and also that characters +must be representable in UTF-16. + +.wen + +. //////////////////////////////////////////////////////////////////////////// +. //////////////////////////////////////////////////////////////////////////// + +.chapter "Events" "CHAPevents" &&& + "Events" +.cindex events + +.new +The events mechanism in Exim can be used to intercept processing at a number +of points. It was originally invented to giave a way to do customised logging +actions (for example, to a database) but can also be used to modify some +processing actions. + +Most installations will never need to use Events. +The support can be left out of a build by defining DISABLE_EVENT=yes +in &_Local/Makefile_&. + +There are two major classes of events: main and transport. +The main configuration option &%event_action%& controls reception events; +a transport option &%event_action%& controls delivery events. + +Both options are a string which is expanded when the event fires. +An example might look like: +.cindex logging custom +.code +event_action = ${if eq {msg:delivery}{$event_name} \ +{${lookup pgsql {SELECT * FROM record_Delivery( \ + '${quote_pgsql:$sender_address_domain}',\ + '${quote_pgsql:${lc:$sender_address_local_part}}', \ + '${quote_pgsql:$domain}', \ + '${quote_pgsql:${lc:$local_part}}', \ + '${quote_pgsql:$host_address}', \ + '${quote_pgsql:${lc:$host}}', \ + '${quote_pgsql:$message_exim_id}')}} \ +} {}} +.endd + +Events have names which correspond to the point in process at which they fire. +The name is placed in the variable &$event_name$& and the event action +expansion must check this, as it will be called for every possible event type. + +The current list of events is: +.display +&`msg:complete after main `& per message +&`msg:delivery after transport `& per recipient +&`msg:rcpt:host:defer after transport `& per recipient per host +&`msg:rcpt:defer after transport `& per recipient +&`msg:host:defer after transport `& per attempt +&`msg:fail:delivery after main `& per recipient +&`msg:fail:internal after main `& per recipient +&`tcp:connect before transport `& per connection +&`tcp:close after transport `& per connection +&`tls:cert before both `& per certificate in verification chain +&`smtp:connect after transport `& per connection +.endd +New event types may be added in future. + +The event name is a colon-separated list, defining the type of +event in a tree of possibilities. It may be used as a list +or just matched on as a whole. There will be no spaces in the name. + +The second column in the table above describes whether the event fires +before or after the action is associates with. Those which fire before +can be used to affect that action (more on this below). + +An additional variable, &$event_data$&, is filled with information varying +with the event type: +.display +&`msg:delivery `& smtp confirmation mssage +&`msg:rcpt:host:defer `& error string +&`msg:rcpt:defer `& error string +&`msg:host:defer `& error string +&`tls:cert `& verification chain depth +&`smtp:connect `& smtp banner +.endd + +The :defer events populate one extra variable: &$event_defer_errno$&. + +For complex operations an ACL expansion can be used in &%event_action%& +however due to the multiple contextx that Exim operates in during +the course of its processing: +.ilist +variables set in transport events will not be visible outside that +transport call +.next +acl_m variables in a server context are lost on a new connection, +and after smtp helo/ehlo/mail/starttls/rset commands +.endlist +Using an ACL expansion with the logwrite modifier can be +a useful way of writing to the main log. + +The expansion of the event_action option should normally +return an empty string. Should it return anything else the +following will be forced: +.display +&`msg:delivery `& (ignored) +&`msg:host:defer `& (ignored) +&`msg:fail:delivery`& (ignored) +&`tcp:connect `& do not connect +&`tcp:close `& (ignored) +&`tls:cert `& refuse verification +&`smtp:connect `& close connection +.endd +No other use is made of the result string. + +For a tcp:connect event, if the connection is being made to a proxy +then the address and port variables will be that of the proxy and not +the target system. + +For tls:cert events, if GnuTLS is in use this will trigger only per +chain element received on the connection. +For OpenSSL it will trigger for every chain element including those +loaded locally. +.wen + +. //////////////////////////////////////////////////////////////////////////// +. //////////////////////////////////////////////////////////////////////////// + .chapter "Adding new drivers or lookup types" "CHID13" &&& "Adding drivers or lookups" .cindex "adding drivers" @@ -35796,6 +38703,12 @@ Add to &_src/config.h.defaults_& the line: Edit &_src/drtables.c_&, adding conditional code to pull in the private header and create a table entry as is done for all the other drivers and lookup types. .next +Edit &_scripts/lookups-Makefile_& if this is a new lookup; there is a for-loop +near the bottom, ranging the &`name_mod`& variable over a list of all lookups. +Add your &`NEWDRIVER`& to that list. +As long as the dynamic module would be named &_newdriver.so_&, you can use the +simple form that most lookups have. +.next Edit &_Makefile_& in the appropriate sub-directory (&_src/routers_&, &_src/transports_&, &_src/auths_&, or &_src/lookups_&); add a line for the new driver or lookup type and add it to the definition of OBJ.