X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/79c1c45de15ec0a5a06648faf5f478c351465127..exim-4_83_RC1:/doc/doc-docbook/spec.xfpt?ds=sidebyside diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 3c5f5bd11..990df6241 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 "4.80" -.set version "4.80" +.include ./local_params .set ACL "access control lists (ACLs)" .set I "    " +.macro copyyear +2014 +.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). @@ -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" @@ -1936,7 +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. @@ -2298,7 +2330,7 @@ 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). @@ -2678,6 +2710,13 @@ 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" @@ -2937,7 +2976,6 @@ 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. -.new . // Keep :help first, then the rest in alphabetical order .vitem &%-bI:help%& .oindex "&%-bI:help%&" @@ -2963,13 +3001,12 @@ 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. -.wen .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 @@ -3078,11 +3115,9 @@ configuration file is output. If a list of configuration files was supplied, the value that is output here is the name of the file that was actually used. -.new .cindex "options" "hiding name of" If the &%-n%& flag is given, then for most modes of &%-bP%& operation the name will not be output. -.wen .cindex "daemon" "process id (pid)" .cindex "pid (process id)" "of daemon" @@ -3686,8 +3721,17 @@ 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%&" @@ -3705,6 +3749,17 @@ 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" @@ -4061,8 +4116,8 @@ 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%&" @@ -4166,6 +4221,20 @@ 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" @@ -4275,7 +4344,7 @@ 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%& @@ -4482,7 +4551,7 @@ 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. @@ -4566,6 +4635,11 @@ 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. .endlist .ecindex IIDclo1 @@ -5329,7 +5403,7 @@ 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 @@ -5483,16 +5557,21 @@ unreachable. 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_hosts = * +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 negociated 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, @@ -5671,7 +5750,7 @@ 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. @@ -5928,9 +6007,14 @@ 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 @@ -6033,7 +6117,7 @@ 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 @@ -6042,7 +6126,7 @@ 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 = ${if def:tls_in_cipher } .endd The &%server_set_id%& option makes Exim remember the authenticated username @@ -6780,7 +6864,7 @@ is used on its own as the result. If the lookup does not succeed, the &`fail`& keyword causes a &'forced expansion failure'& &-- see section &<>& for an explanation of what this means. -The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, and TXT, +The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, TLSA and TXT, and, when Exim is compiled with IPv6 support, AAAA (and A6 if that is also configured). If no type is given, TXT is assumed. When the type is PTR, the data can be an IP address, written as normal; inversion and the addition of @@ -6871,6 +6955,14 @@ has two space-separated fields: an authorization code and a target host name. The authorization code can be &"Y"& for yes, &"N"& for no, &"X"& for explicit authorization required but absent, or &"?"& for unknown. +.cindex "A+" "in &(dnsdb)& lookup" +The pseudo-type A+ performs an A6 lookup (if configured) followed by an AAAA +and then an A lookup. All results are returned; defer processing +(see below) is handled separately for each lookup. Example: +.code +${lookup dnsdb {>; a+=$sender_helo_name}} +.endd + .section "Multiple dnsdb lookups" "SECID67" In the previous sections, &(dnsdb)& lookups for a single domain are described. @@ -6891,11 +6983,16 @@ 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. +Modifiers for &(dnsdb)& lookups are givien 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 -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 +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 @@ -6908,6 +7005,21 @@ ${lookup dnsdb{a=one.host.com:two.host.com}} Thus, in the default case, as long as at least one of the DNS lookups yields some data, the lookup succeeds. +.new +.cindex "DNSSEC" "dns lookup" +Use of &(DNSSEC)& is controlled by a dnssec modifier. +The possible keywords are +&"dnssec_strict"&, &"dnssec_lax"&, and &"dnssec_never"&. +With &"strict"& or &"lax"& DNSSEC information is requested +with the lookup. +With &"strict"& a response from the DNS resolver that +is not labelled as authenticated data +is treated as equivalent to a temporary DNS error. +The default is &"never"&. + +See also the &$lookup_dnssec_authenticated$& variable. +.wen + @@ -6972,6 +7084,18 @@ 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. +.new +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_&. +.wen + .section "LDAP quoting" "SECID68" .cindex "LDAP" "quoting" @@ -7118,6 +7242,9 @@ 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 +.new +&`SERVERS `& set alternate server list for this query only +.wen &`SIZE `& set the limit for the number of entries returned &`TIME `& set the maximum waiting time for a query .endd @@ -7139,6 +7266,15 @@ 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. +.new +The SERVERS parameter allows you to specify an alternate list of ldap servers +to use for an individual lookup. The global ldap_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. +.wen 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: @@ -7445,7 +7581,7 @@ ${lookup sqlite {/some/thing/sqlitedb \ .endd In a list, the syntax is similar. For example: .code -domainlist relay_domains = sqlite;/some/thing/sqlitedb \ +domainlist relay_to_domains = sqlite;/some/thing/sqlitedb \ select * from relays where ip='$sender_host_address'; .endd The only character affected by the &%quote_sqlite%& operator is a single @@ -7527,13 +7663,13 @@ 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 @@ -7637,7 +7773,7 @@ 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: @@ -8104,7 +8240,7 @@ 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 @@ -8184,10 +8320,13 @@ 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 @@ -8215,6 +8354,44 @@ 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. +.new +.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 +.wen + .section "Temporary DNS errors when looking up host information" &&& "SECTtemdnserr" @@ -8273,7 +8450,7 @@ 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 @@ -8285,33 +8462,6 @@ 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" @@ -8473,7 +8623,7 @@ 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. @@ -8718,6 +8868,88 @@ 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$& is set to the number of +arguments. The named ACL (see chapter &<>&) is called +and may use the variables; if another acl expansion is used the values +are restored after it returns. If the ACL sets +a value using a "message =" modifier and returns accept or deny, the value becomes +the result of the expansion. +If no message is set and the ACL returns accept or deny +the expansion result is an empty string. +If the ACL returns defer the result is a forced-fail. Otherwise the expansion fails. + + +.new +.vitem "&*${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 retrive 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 containin 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 modifer 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 +may output a number of seconds since epoch +if the modifier "int" is used. + +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 elenment tags are omitted. + +If not otherwise noted field values are presented in human-readable form. +.wen + .vitem "&*${dlfunc{*&<&'file'&>&*}{*&<&'function'&>&*}{*&<&'arg'&>&*}&&& {*&<&'arg'&>&*}...}*&" .cindex &%dlfunc%& @@ -9050,6 +9282,44 @@ of <&'string2'&>, whichever is the shorter. Do not confuse &%length%& with &%strlen%&, which gives the length of a string. +.vitem "&*${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: $value}} +.endd +yields &"result: 99"&. + +If {<&'string3'&>} is omitted, an empty string is used for string3. +If {<&'string2'&>} is also omitted, the value that was +extracted is used. +You can use &`fail`& instead of {<&'string3'&>} as in a string extract. + + .vitem "&*${lookup{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&& {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" This is the first of one of two different types of lookup item, which are both @@ -9348,6 +9618,20 @@ 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: @@ -9508,6 +9792,29 @@ 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 seperator. 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" @@ -9527,6 +9834,7 @@ 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. + .vitem &*${domain:*&<&'string'&>&*}*& .cindex "domain" "extraction" .cindex "expansion" "domain extraction" @@ -9661,6 +9969,16 @@ This operator converts a hex string into one that is base64 encoded. This can be useful for processing the output of the MD5 and SHA-1 hashing functions. + +.vitem &*${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`&. + + .vitem &*${lc:*&<&'string'&>&*}*& .cindex "case forcing in strings" .cindex "string" "case forcing" @@ -9686,6 +10004,25 @@ See the description of the general &%length%& item above for details. Note that when &%length%& is used as an operator. +.vitem &*${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 &*${local_part:*&<&'string'&>&*}*& .cindex "expansion" "local part extraction" .cindex "&%local_part%& expansion item" @@ -9725,6 +10062,7 @@ Letters in IPv6 addresses are always output in lower case. .vitem &*${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. @@ -9808,12 +10146,12 @@ 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} +${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.127} .endd returns .code 4.2.0.192 -3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2 +f.7.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2 .endd @@ -9862,11 +10200,24 @@ variables or headers inside regular expressions. .vitem &*${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. +.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" .cindex "file" "extracting characteristics" @@ -9935,6 +10286,14 @@ 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 &`?`&. .endlist @@ -9973,8 +10332,8 @@ ${if >{$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. @@ -9983,12 +10342,27 @@ 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; @@ -10177,6 +10551,8 @@ ${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'&>&*}*& @@ -10720,7 +11096,16 @@ 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 &$authenticated_sender$& @@ -10933,6 +11318,12 @@ 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 @@ -11165,6 +11556,16 @@ 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. +.new +.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. +It will be empty if &(DNSSEC)& was not requested, +&"no"& if the result was not labelled as authenticated data +and &"yes"& if it was. +.wen + .vitem &$mailstore_basename$& .vindex "&$mailstore_basename$&" This variable is set only when doing deliveries in &"mailstore"& format in the @@ -11603,6 +12004,12 @@ 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 "&$runrc$&" @@ -11694,7 +12101,6 @@ driver that successfully authenticated the client from which the message was received. It is empty if there was no successful authentication. See also &$authenticated_id$&. -.new .vitem &$sender_host_dnssec$& .vindex "&$sender_host_dnssec$&" If &$sender_host_name$& has been populated (by reference, &%hosts_lookup%& or @@ -11705,7 +12111,7 @@ other times, this variable is false. It is likely that you will need to coerce DNSSEC support on in the resolver library, by setting: .code -dns_use_dnssec = 1 +dns_dnssec_ok = 1 .endd Exim does not perform DNSSEC validation itself, instead leaving that to a @@ -11716,7 +12122,6 @@ with DNSSEC, only the reverse DNS. If you have changed &%host_lookup_order%& so that &`bydns`& is not the first mechanism in the list, then this variable will be false. -.wen .vitem &$sender_host_name$& @@ -11917,20 +12322,81 @@ 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'&. -.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). -.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. + +.new +.vitem &$tls_in_ourcert$& +.vindex "&$tls_in_ourcert$&" +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%& or &%sha1%& operator, +or a &%def%& condition. +.wen + +.new +.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%& or &%sha1%& operator, +or a &%def%& condition. +.wen + +.new +.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%& or &%sha1%& operator, +or a &%def%& condition. +.wen + +.new +.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%& or &%sha1%& operator, +or a &%def%& condition. +.wen + +.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 &$tls_certificate_verfied$& 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 @@ -11939,23 +12405,39 @@ 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 &$tls_in_peerdn$& +.vindex "&$tls_in_peerdn$&" .vindex "&$tls_peerdn$&" 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. + +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 &$tls_sni$& +.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. + +.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 @@ -11966,8 +12448,15 @@ 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. .vitem &$tod_bsdinbox$& @@ -12011,6 +12500,12 @@ 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, @@ -12422,7 +12917,7 @@ 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. @@ -12666,6 +13161,7 @@ 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" @@ -12719,12 +13215,14 @@ 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_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" @@ -12820,6 +13318,7 @@ See also the &'Policy controls'& section above. .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 &%tls_advertise_hosts%& "advertise TLS to these hosts" .endtable @@ -12865,12 +13364,10 @@ 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" -.new -.row &%dns_use_dnssec%& "parameter for resolver" -.wen .row &%dns_use_edns0%& "parameter for resolver" .row &%hold_domains%& "hold delivery for these domains" .row &%local_interfaces%& "for routing checks" @@ -12918,6 +13415,8 @@ Those options that undergo string expansion before use are marked with .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 @@ -12931,6 +13430,11 @@ A more detailed analysis of the issues is provided by Dan Bernstein: &url(http://cr.yp.to/smtp/8bitmime.html) .endd +To log received 8BITMIME status use +.code +log_selector = +8bitmime +.endd + .option acl_not_smtp main string&!! unset .cindex "&ACL;" "for non-SMTP messages" .cindex "non-SMTP messages" "ACLs for" @@ -12966,6 +13470,16 @@ 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&!! unset +.cindex "DATA" "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_etrn main string&!! unset .cindex "ETRN" "ACL for" This option defines the ACL that is run when an SMTP ETRN command is @@ -13110,10 +13624,10 @@ 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. @@ -13360,6 +13874,9 @@ 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 "&$domain$&" @@ -13481,6 +13998,17 @@ 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" @@ -13511,18 +14039,6 @@ to set in them. See &%dns_retrans%& above. -.new -.option dns_use_dnssec 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. -.wen - - .option dns_use_edns0 main integer -1 .cindex "DNS" "resolver options" .cindex "DNS" "EDNS0" @@ -13747,6 +14263,17 @@ 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 @@ -14497,6 +15024,8 @@ Possible options may include: .next &`no_tlsv1_2`& .next +&`safari_ecdhe_ecdsa_bug`& +.next &`single_dh_use`& .next &`single_ecdh_use`& @@ -14512,6 +15041,13 @@ 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" @@ -14586,6 +15122,15 @@ 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 recieved. 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 @@ -14838,7 +15383,7 @@ 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}}\ @@ -15081,8 +15626,15 @@ 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" @@ -15132,10 +15684,9 @@ 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" @@ -15701,7 +16252,7 @@ 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. -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. @@ -15775,6 +16326,28 @@ The available primes are: 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_ocsp_file main string&!! unset +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. + .option tls_on_connect_ports main "string list" unset This option specifies a list of incoming SSMTP (aka SMTPS) ports that should @@ -15842,6 +16415,9 @@ use OpenSSL with a directory. See &<>& for discussion of when this option might be re-expanded. +A forced expansion failure or setting to an empty string is equivalent to +being unset. + .option tls_verify_hosts main "host list&!!" unset .cindex "TLS" "client certificate verification" @@ -16179,7 +16755,7 @@ 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 @@ -16208,7 +16784,8 @@ be specified using &%condition%&. .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 @@ -16217,6 +16794,7 @@ 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. @@ -16361,11 +16939,12 @@ 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, +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 @@ -16374,10 +16953,13 @@ 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. @@ -16394,11 +16976,12 @@ 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, +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 @@ -16407,10 +16990,13 @@ 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. @@ -17047,7 +17633,8 @@ 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 @@ -17061,7 +17648,8 @@ 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. @@ -17246,6 +17834,33 @@ when there is a DNS lookup error. +.new +.option dnssec_request_domains dnslookup "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 A6, AAAA, A lookup sequence. +.wen + + + +.new +.option dnssec_require_domains dnslookup "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 wil be ignored and logged as a host-lookup failure. +This applies to all of the SRV, MX A6, AAAA, A lookup sequence. +.wen + + + .option mx_domains dnslookup "domain list&!!" unset .cindex "MX record" "required to exist" .cindex "SRV record" "required to exist" @@ -18417,7 +19032,6 @@ quote just the command. An item such as .endd is interpreted as a pipe with a rather strange command name, and no arguments. -.new 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 @@ -18427,7 +19041,6 @@ 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. -.wen .next .cindex "file" "in redirection list" @@ -19369,7 +19982,8 @@ 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" @@ -19404,16 +20018,19 @@ 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, +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 @@ -19426,16 +20043,21 @@ 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; 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. + .option headers_rewrite transports string unset @@ -19740,7 +20362,7 @@ 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 @@ -21356,10 +21978,10 @@ 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 @@ -21467,6 +22089,15 @@ 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 @@ -21619,6 +22250,23 @@ 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. @@ -21980,6 +22628,9 @@ 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" @@ -22017,7 +22668,7 @@ 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 @@ -22114,9 +22765,34 @@ details. .new +.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 A6, AAAA, A lookup sequence. +.wen + + + +.new +.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 wil be ignored and logged as a host-lookup failure. +This applies to all of the SRV, MX A6, AAAA, A lookup sequence. +.wen + + + .option dscp smtp string&!! unset -.cindex "DCSP" -.cindex "DiffServ" +.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. @@ -22125,10 +22801,9 @@ Common values include &`throughput`&, &`mincost`&, and on newer systems 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 packets will have any effect, not be stripped by networking +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. -.wen .option fallback_hosts smtp "string list" unset @@ -22263,6 +22938,13 @@ 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&!!" * +.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. +Note that the default is to not use TLS. + .option hosts_max_try smtp integer 5 .cindex "host" "maximum number to try" @@ -22331,6 +23013,18 @@ 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 @@ -22346,6 +23040,12 @@ 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&!!" unset +.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. + .option interface smtp "string list&!!" unset .cindex "bind IP address" .cindex "IP address" "binding" @@ -22527,7 +23227,6 @@ 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 .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 @@ -22537,7 +23236,6 @@ If the parameter offered by the server is too small, then the TLS handshake will fail. Only supported when using GnuTLS. -.wen .option tls_privatekey smtp string&!! unset @@ -22572,7 +23270,7 @@ ciphers is a preference order. .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 $tls_out_sni variable and causes any TLS session to pass this value as the Server Name Indication extension to the remote side, which can be used by the remote side to select an appropriate certificate and private key for the session. @@ -22598,6 +23296,19 @@ unknown state), opens a new one to the same host, and then tries the delivery in clear. +.option tls_try_verify_hosts smtp "host list&!! unset +.cindex "TLS" "server certificate verification" +.cindex "certificate" "verification of server" +This option gives a list of hosts for which, on encrypted connections, +certificate verification will be tried but need not succeed. +The &%tls_verify_certificates%& option must also be set. +Note that unless the host is in this list +TLS connections will be denied to hosts using self-signed certificates +when &%tls_verify_certificates%& is set. +The &$tls_out_certificate_verified$& variable is set when +certificate verification succeeds. + + .option tls_verify_certificates smtp string&!! unset .cindex "TLS" "server certificate verification" .cindex "certificate" "verification of server" @@ -22612,6 +23323,20 @@ single file if you are using GnuTLS. The values of &$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-compatability, +if neither tls_verify_hosts nor tls_try_verify_hosts are 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. + @@ -23238,7 +23963,7 @@ 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 @@ -23844,11 +24569,14 @@ 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 messasges. +Typically it will be the user name used for authentication. .option driver authenticators string unset @@ -24008,10 +24736,10 @@ 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 @@ -24218,7 +24946,7 @@ 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. @@ -24665,7 +25393,7 @@ dovecot_plain: driver = dovecot public_name = PLAIN server_socket = /var/run/dovecot/auth-client - server_set_id = $auth2 + server_set_id = $auth1 dovecot_ntlm: driver = dovecot @@ -25076,10 +25804,11 @@ name of a directory (for OpenSSL it can be either). .next The default value for &%tls_dhparam%& differs for historical reasons. .next -.vindex "&$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: @@ -25093,12 +25822,10 @@ option). The &%tls_require_ciphers%& options operate differently, as described in the sections &<>& and &<>&. .next -.new 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). -.wen .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 @@ -25281,10 +26008,10 @@ 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. Prior to Exim 4.80, an older API of GnuTLS was used, and Exim supported three @@ -25370,7 +26097,7 @@ tls_dhparam = none 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 -documetnation for &%tls_dhparam%& for the complete list. +documentation for &%tls_dhparam%& for the complete list. See the command .code @@ -25386,15 +26113,13 @@ 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$& is reset &-- see section -&<>&.) Once TLS has been established, the ACLs that run for subsequent SMTP commands can check the name of the cipher suite and vary their actions accordingly. The @@ -25403,6 +26128,9 @@ example, OpenSSL uses the name DES-CBC3-SHA for the cipher suite which in other contexts is known as TLS_RSA_WITH_3DES_EDE_CBC_SHA. Check the OpenSSL or GnuTLS documentation for more details. +For outgoing SMTP deliveries, &$tls_out_cipher$& is used and logged +(again depending on the &%tls_cipher%& log selector). + .section "Requesting and verifying client certificates" "SECID183" .cindex "certificate" "verification of client" @@ -25439,29 +26167,96 @@ fact that no certificate was verified, and vary their actions accordingly. For example, you can insist on a certificate before accepting a message for relaying, but not when the message is destined for local delivery. -.vindex "&$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 the 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, +or with GnuTLS earlier than version 3.1.3, +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. + +.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" @@ -25510,6 +26305,25 @@ for OpenSSL only (not GnuTLS), a directory, that contains a collection of expected server certificates. 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 @@ -25530,12 +26344,12 @@ 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$& variables are emptied. (Until the first connection, they contain the values that were set when the message was received.) If STARTTLS is subsequently successfully obeyed, these variables are set to the relevant values for the @@ -25545,8 +26359,8 @@ outgoing connection. .section "Use of TLS Server Name Indication" "SECTtlssni" .cindex "TLS" "Server Name Indication" -.vindex "&$tls_sni$&" -.oindex "&%tls_sni%&" +.vindex "&$tls_in_sni$&" +.oindex "&%tls_in_sni%&" With TLS1.0 or above, there is an extension mechanism by which extra information can be included at various points in the protocol. One of these extensions, documented in RFC 6066 (and before that RFC 4366) is @@ -25573,14 +26387,14 @@ different clients. Or even negotiate different cipher suites. The &%tls_sni%& option on an SMTP transport is an expanded string; the result, if not empty, will be sent on a TLS session as part of the handshake. There's nothing more to it. Choosing a sensible value not derived insecurely is the -only point of caution. The &$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: @@ -25596,6 +26410,9 @@ 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_verify_certificates%& .endlist Great care should be taken to deal with matters of case, various injection @@ -25687,11 +26504,19 @@ 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 @@ -25704,6 +26529,22 @@ 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. @@ -25780,6 +26621,7 @@ 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" @@ -25788,6 +26630,7 @@ 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_etrn%& "ACL for ETRN" .irow &%acl_smtp_expn%& "ACL for EXPN" .irow &%acl_smtp_helo%& "ACL for HELO or EHLO" @@ -25902,6 +26745,10 @@ 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 @@ -25911,13 +26758,47 @@ 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" +.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 specfied by &%acl_smtp_data_prdr%& happens after a message +has been recieved, and is executed for each recipient of the message. +The test may accept or deny for inividual 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 +for this can be disabled when the MAIL-time $smtp_command included +"PRDR". Any required difference in behaviour of the main DATA-time +ACL should however depend on the PRDR-time ACL having run, as Exim +will avoid doing so in some situations (eg. single-recipient mails). + +See also the &%prdr_enable%& global option +and the &%hosts_try_prdr%& smtp transport option. + +This ACL is evaluated after &%acl_smtp_dkim%& but before &%acl_smtp_data%&. +If the ACL is not defined, processing completes as if +the feature was not requested by the client. .section "The QUIT ACL" "SECTQUITACL" .cindex "QUIT, ACL for" @@ -25948,7 +26829,7 @@ connection is closed. In these special cases, the QUIT ACL does not run. .section "The not-QUIT ACL" "SECTNOTQUITACL" .vindex &$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. @@ -26302,8 +27183,8 @@ 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 @@ -26421,7 +27302,7 @@ 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: @@ -26542,12 +27423,12 @@ 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: @@ -26594,7 +27475,7 @@ 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 @@ -26745,13 +27626,33 @@ 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 + @@ -26811,6 +27712,36 @@ 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. +It is usable in the RCPT ACL and valid only for single-recipient mails forwarded +from one SMTP connection to another. If a recipient-verify callout connection is +requested in the same ACL it is held open and used for the data, otherwise one is made +after the 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. + +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. + +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 log line +is tagged with ">>" rather than "=>" and appears 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" @@ -26829,6 +27760,30 @@ 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" @@ -27019,7 +27974,7 @@ 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 @@ -27028,13 +27983,18 @@ warn dnslists = sbl.spamhaus.org : \ add_header = X-blacklisted-at: $dnslist_domain .endd The &%add_header%& modifier is permitted in the MAIL, RCPT, PREDATA, DATA, -MIME, and non-SMTP ACLs (in other words, those that are concerned with +MIME, DKIM, and non-SMTP ACLs (in other words, those that are concerned with receiving a message). The message must ultimately be accepted for &%add_header%& to have any significant effect. You can use &%add_header%& with any ACL verb, including &%deny%& (though this is potentially useful only in a RCPT ACL). -If the data for the &%add_header%& modifier contains one or more newlines that +Headers will not be added to the message if the modifier is used in +DATA, MIME or DKIM ACLs for messages delivered by cutthrough routing. + +Leading and trailing newlines are removed from +the data for the &%add_header%& modifier; if it then +contains one or more newlines that are not followed by a space or a tab, it is assumed to contain multiple header lines. Each one is checked for valid syntax; &`X-ACL-Warn:`& is added to the front of any line that is not a valid header line. @@ -27052,7 +28012,9 @@ message is rejected after DATA or by the non-SMTP ACL, all added header lines are included in the entry that is written to the reject log. .cindex "header lines" "added; visibility of" -Header lines are not visible in string expansions until they are added to the +Header lines are not visible in string expansions +of message headers +until they are added to the message. It follows that header lines defined in the MAIL, RCPT, and predata ACLs are not visible until the DATA ACL and MIME ACLs are run. Similarly, header lines that are added by the DATA or MIME ACLs are not visible in those @@ -27061,7 +28023,9 @@ passing data between (for example) the MAIL and RCPT ACLs. If you want to do this, you can use ACL variables, as described in section &<>&. -The &%add_header%& modifier acts immediately it is encountered during the +The list of headers yet to be added is given by the &%$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`& @@ -27110,10 +28074,83 @@ 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 &<>&. @@ -27131,6 +28168,7 @@ 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 @@ -27140,6 +28178,12 @@ 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. + 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 @@ -27228,7 +28272,7 @@ encrypted = * .endd -.vitem &*hosts&~=&~*&<&'&~host&~list'&> +.vitem &*hosts&~=&~*&<&'host&~list'&> .cindex "&%hosts%& ACL condition" .cindex "host" "ACL checking" .cindex "&ACL;" "testing the client host" @@ -27370,6 +28414,23 @@ This condition checks whether the sending host (the client) is authorized to send email. Details of how this works are given in section &<>&. +.new +.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. +.wen + .vitem &*verify&~=&~header_sender/*&<&'options'&> .cindex "&%verify%& ACL condition" .cindex "&ACL;" "verifying sender in the header" @@ -27888,7 +28949,7 @@ 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 @@ -27981,6 +29042,13 @@ 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" @@ -28362,6 +29430,7 @@ 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 @@ -28383,6 +29452,9 @@ 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 @@ -28898,16 +29970,16 @@ 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 @@ -29025,7 +30097,9 @@ 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 &%aveserver%& @@ -29051,6 +30125,7 @@ number, and a port, separated by space, as in the second of these examples: 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 : 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 @@ -29059,6 +30134,22 @@ 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. @@ -29143,6 +30234,24 @@ 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 addres 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. @@ -31265,7 +32374,7 @@ 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 @@ -31274,15 +32383,25 @@ 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. + +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. @@ -31519,6 +32638,8 @@ 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 @@ -33142,6 +34263,7 @@ 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 @@ -33241,6 +34363,11 @@ 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 @@ -33256,6 +34383,12 @@ 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 &">"&. @@ -33348,7 +34481,7 @@ 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 @@ -33366,6 +34499,7 @@ the following table: &`R `& on &`<=`& lines: reference for local bounce &` `& on &`=>`& &`**`& and &`==`& lines: router name &`S `& size of message +&`SNI `& server name indication from TLS client hello &`ST `& shadow transport name &`T `& on &`<=`& lines: message subject (topic) &` `& on &`=>`& &`**`& and &`==`& lines: transport name @@ -33432,6 +34566,7 @@ 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 @@ -33461,9 +34596,10 @@ 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_confirmation `& SMTP confirmation on => lines &` smtp_connection `& 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 @@ -33479,6 +34615,14 @@ selection marked by asterisks: 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 @@ -33665,7 +34809,8 @@ 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. @@ -33724,6 +34869,11 @@ 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 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 @@ -33889,20 +35039,28 @@ 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 +.new +The &*-C*& option is used to specify an alternate &_exim.conf_& which might +contain alternate exim configuration the queue management might be using. +.wen + +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-insensitve search. The field that is +tested is not enclosed in angle brackets. .vitem &*-s*&&~<&'regex'&> Match against the size field. @@ -33938,6 +35096,9 @@ 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. @@ -35126,6 +36287,85 @@ 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 analagous 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" @@ -35583,7 +36823,7 @@ unqualified domain &'foundation'&. . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.chapter "Support for DKIM (DomainKeys Identified Mail)" "CHID12" &&& +.chapter "Support for DKIM (DomainKeys Identified Mail)" "CHAPdkim" &&& "DKIM Support" .cindex "DKIM" @@ -35598,7 +36838,9 @@ 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 @@ -35689,6 +36931,10 @@ 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 acccept, 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 @@ -35803,7 +37049,7 @@ 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 @@ -35834,7 +37080,7 @@ 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 @@ -35880,6 +37126,12 @@ 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.