X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/ead05c2db0843fa927859b6d697400bc946c0d0b..b5a70bdfa38bcc3e1143f8fe6f63e7613f03e690:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 2f06f126f..579c112c9 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -45,7 +45,7 @@ . the element must also be updated for each new edition. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.75" +.set previousversion "4.80" .set version "4.80" .set ACL "access control lists (ACLs)" @@ -1647,7 +1647,6 @@ architecture and operating system for itself, but the defaults can be overridden if necessary. -.new .section "PCRE library" "SECTpcre" .cindex "PCRE library" Exim no longer has an embedded PCRE library as the vast majority of @@ -1662,7 +1661,6 @@ If your operating system has no PCRE support then you will need to obtain and build the current PCRE from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/). More information on PCRE is available at &url(http://www.pcre.org/). -.wen .section "DBM libraries" "SECTdb" .cindex "DBM libraries" "discussion of" @@ -1873,14 +1871,12 @@ SUPPORT_TLS=yes TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto TLS_INCLUDE=-I/usr/local/openssl/include/ .endd -.new .cindex "pkg-config" "OpenSSL" If you have &'pkg-config'& available, then instead you can just use: .code SUPPORT_TLS=yes USE_OPENSSL_PC=openssl .endd -.wen .cindex "USE_GNUTLS" If GnuTLS is installed, you should set .code @@ -1896,7 +1892,6 @@ USE_GNUTLS=yes TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt TLS_INCLUDE=-I/usr/gnu/include .endd -.new .cindex "pkg-config" "GnuTLS" If you have &'pkg-config'& available, then instead you can just use: .code @@ -1904,7 +1899,6 @@ SUPPORT_TLS=yes USE_GNUTLS=yes USE_GNUTLS_PC=gnutls .endd -.wen You do not need to set TLS_INCLUDE if the relevant directory is already specified in INCLUDE. Details of how to configure Exim to make use of TLS are @@ -2133,7 +2127,6 @@ files or libraries are required. When a lookup type is not included in the binary, attempts to configure Exim to use it cause run time configuration errors. -.new .cindex "pkg-config" "lookups" .cindex "pkg-config" "authenticators" Many systems now use a tool called &'pkg-config'& to encapsulate information @@ -2153,7 +2146,6 @@ AUTH_GSASL_PC=libgsasl AUTH_HEIMDAL_GSSAPI=yes AUTH_HEIMDAL_GSSAPI_PC=heimdal-gssapi .endd -.wen .cindex "Perl" "including support for" Exim can be linked with an embedded Perl interpreter, allowing Perl @@ -2686,6 +2678,15 @@ no arguments. This option is an alias for &%-bV%& and causes version information to be displayed. +.new +.vitem &%-Ac%& &&& + &%-Am%& +.oindex "&%-Ac%&" +.oindex "&%-Am%&" +These options are used by Sendmail for selecting configuration files and are +ignored by Exim. +.wen + .vitem &%-B%&<&'type'&> .oindex "&%-B%&" .cindex "8-bit characters" @@ -2945,6 +2946,34 @@ 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%&" +.cindex "querying exim information" +We shall provide various options starting &`-bI:`& for querying Exim for +information. The output of many of these will be intended for machine +consumption. This one is not. The &%-bI:help%& option asks Exim for a +synopsis of supported options beginning &`-bI:`&. Use of any of these +options shall cause Exim to exit after producing the requested output. + +.vitem &%-bI:dscp%& +.oindex "&%-bI:dscp%&" +.cindex "DSCP" "values" +This option causes Exim to emit an alphabetically sorted list of all +recognised DSCP names. + +.vitem &%-bI:sieve%& +.oindex "&%-bI:sieve%&" +.cindex "Sieve filter" "capabilities" +This option causes Exim to emit an alphabetically sorted list of all supported +Sieve protocol extensions on stdout, one per line. This is anticipated to be +useful for ManageSieve (RFC 5804) implementations, in providing that protocol's +&`SIEVE`& capability response line. As the precise list may depend upon +compile-time build options, which this option will adapt to, this is the only +way to guarantee a correct response. +.wen + .vitem &%-bm%& .oindex "&%-bm%&" .cindex "local message reception" @@ -2991,6 +3020,26 @@ The specified sender is treated as if it were given as the argument to the preference to the address taken from the message. The caller of Exim must be a trusted user for the sender of a message to be set in this way. +.vitem &%-bmalware%&&~<&'filename'&> +.oindex "&%-bmalware%&" +.cindex "testing", "malware" +.cindex "malware scan test" +This debugging option causes Exim to scan the given file, +using the malware scanning framework. The option of &%av_scanner%& influences +this option, so if &%av_scanner%&'s value is dependent upon an expansion then +the expansion should have defaults which apply to this invocation. ACLs are +not invoked, so if &%av_scanner%& references an ACL variable then that variable +will never be populated and &%-bmalware%& will fail. + +Exim will have changed working directory before resolving the filename, so +using fully qualified pathnames is advisable. Exim will be running as the Exim +user when it tries to open the file, rather than as the invoking user. +This option requires admin privileges. + +The &%-bmalware%& option will not be extended to be more generally useful, +there are better tools for file-scanning. This option exists to help +administrators verify their Exim and AV scanner configuration. + .vitem &%-bnq%& .oindex "&%-bnq%&" .cindex "address qualification, suppressing" @@ -3038,6 +3087,12 @@ 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" If &%log_file_path%& or &%pid_file_path%& are given, the names of the @@ -3251,26 +3306,6 @@ above concerning senders and qualification do not apply. In this situation, Exim behaves in exactly the same way as it does when receiving a message via the listening daemon. -.vitem &%-bmalware%&&~<&'filename'&> -.oindex "&%-bmalware%&" -.cindex "testing", "malware" -.cindex "malware scan test" -This debugging option causes Exim to scan the given file, -using the malware scanning framework. The option of &%av_scanner%& influences -this option, so if &%av_scanner%&'s value is dependent upon an expansion then -the expansion should have defaults which apply to this invocation. ACLs are -not invoked, so if &%av_scanner%& references an ACL variable then that variable -will never be populated and &%-bmalware%& will fail. - -Exim will have changed working directory before resolving the filename, so -using fully qualified pathnames is advisable. Exim will be running as the Exim -user when it tries to open the file, rather than as the invoking user. -This option requires admin privileges. - -The &%-bmalware%& option will not be extended to be more generally useful, -there are better tools for file-scanning. This option exists to help -administrators verify their Exim and AV scanner configuration. - .vitem &%-bt%& .oindex "&%-bt%&" .cindex "testing" "addresses" @@ -3660,8 +3695,19 @@ 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)" +.new +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. +.wen .vitem &%-h%&&~<&'number'&> .oindex "&%-h%&" @@ -3679,6 +3725,19 @@ 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%&. +.new +.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. +.wen + .vitem &%-M%&&~<&'message&~id'&>&~<&'message&~id'&>&~... .oindex "&%-M%&" .cindex "forcing delivery" @@ -3919,9 +3978,9 @@ for that message. .vitem &%-n%& .oindex "&%-n%&" -.cindex "Sendmail compatibility" "&%-n%& option ignored" -This option is interpreted by Sendmail to mean &"no aliasing"&. It is ignored -by Exim. +This option is interpreted by Sendmail to mean &"no aliasing"&. +For normal modes of operation, it is ignored by Exim. +When combined with &%-bP%& it suppresses the name of an option from being output. .vitem &%-O%&&~<&'data'&> .oindex "&%-O%&" @@ -4540,6 +4599,13 @@ 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. + +.new +.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. +.wen .endlist .ecindex IIDclo1 @@ -5303,7 +5369,7 @@ 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 @@ -5645,7 +5711,7 @@ 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. @@ -6007,7 +6073,7 @@ The example PLAIN authenticator looks like this: # server_set_id = $auth2 # server_prompts = : # server_condition = Authentication is not yet configured -# server_advertise_condition = ${if def:tls_cipher } +# server_advertise_condition = ${if def:tls_in_cipher } .endd And the example LOGIN authenticator looks like this: .code @@ -6016,7 +6082,7 @@ 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 @@ -6026,16 +6092,16 @@ that it implements the details of the specific authentication mechanism, i.e. PLAIN or LOGIN. The &%server_advertise_condition%& setting controls when Exim offers authentication to clients; in the examples, this is only when TLS or SSL has been started, so to enable the authenticators you also -need to add support for TLS as described in &<>&. +need to add support for TLS as described in section &<>&. The &%server_condition%& setting defines how to verify that the username and password are correct. In the examples it just produces an error message. To make the authenticators work, you can use a string expansion -expression like one of the examples in &<>&. +expression like one of the examples in chapter &<>&. Beware that the sequence of the parameters to PLAIN and LOGIN differ; the -usercode and password are in different positions. &<>& -covers both. +usercode and password are in different positions. +Chapter &<>& covers both. .ecindex IIDconfiwal @@ -6245,7 +6311,6 @@ using Berkeley DB versions 3 or 4, it opens existing databases for reading with the DB_UNKNOWN option. This enables it to handle any of the types of database that the library supports, and can be useful for accessing DBM files created by other applications. (For earlier DB versions, DB_HASH is always used.) -.new .next .cindex "lookup" "dbmjz" .cindex "lookup" "dbm &-- embedded NULs" @@ -6257,7 +6322,6 @@ ASCII NUL characters to form the lookup key. An example usage would be to authenticate incoming SMTP calls using the passwords from Cyrus SASL's &_/etc/sasldb2_& file with the &(gsasl)& authenticator or Exim's own &(cram_md5)& authenticator. -.wen .next .cindex "lookup" "dbmnz" .cindex "lookup" "dbm &-- terminating zero" @@ -6756,13 +6820,11 @@ is used on its own as the result. If the lookup does not succeed, the &`fail`& keyword causes a &'forced expansion failure'& &-- see section &<>& for an explanation of what this means. -.new The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, and TXT, and, when Exim is compiled with IPv6 support, AAAA (and A6 if that is also configured). If no type is given, TXT is assumed. When the type is PTR, the data can be an IP address, written as normal; inversion and the addition of &%in-addr.arpa%& or &%ip6.arpa%& happens automatically. For example: -.wen .code ${lookup dnsdb{ptr=192.168.4.5}{$value}fail} .endd @@ -6789,13 +6851,11 @@ white space is ignored. .cindex "TXT record" "in &(dnsdb)& lookup" .cindex "SPF record" "in &(dnsdb)& lookup" -.new For TXT records with multiple items of data, only the first item is returned, unless a separator for them is specified using a comma after the separator character followed immediately by the TXT record item separator. To concatenate items without a separator, use a semicolon instead. For SPF records the default behaviour is to concatenate multiple items without using a separator. -.wen .code ${lookup dnsdb{>\n,: txt=a.b.example}} ${lookup dnsdb{>\n; txt=a.b.example}} @@ -7425,7 +7485,7 @@ ${lookup sqlite {/some/thing/sqlitedb \ .endd In a list, the syntax is similar. For example: .code -domainlist relay_domains = sqlite;/some/thing/sqlitedb \ +domainlist relay_to_domains = sqlite;/some/thing/sqlitedb \ select * from relays where ip='$sender_host_address'; .endd The only character affected by the &%quote_sqlite%& operator is a single @@ -7507,13 +7567,13 @@ subject is not in the set. If the end of the list is reached without the subject having matched any of the patterns, it is in the set if the last item was a negative one, but not if it was a positive one. For example, the list in .code -domainlist relay_domains = !a.b.c : *.b.c +domainlist relay_to_domains = !a.b.c : *.b.c .endd matches any domain ending in &'.b.c'& except for &'a.b.c'&. Domains that match neither &'a.b.c'& nor &'*.b.c'& do not match, because the last item in the list is positive. However, if the setting were .code -domainlist relay_domains = !a.b.c +domainlist relay_to_domains = !a.b.c .endd then all domains other than &'a.b.c'& would match because the last item in the list is negative. In other words, a list that ends with a negative item behaves @@ -7617,7 +7677,7 @@ 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: @@ -8698,6 +8758,23 @@ 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$& is set to the number of +arguments. The named ACL (see chapter &<>&) is called +and may use the variables; if another acl expansion is used the values +are overwritten. If the ACL sets +a value using a "message =" modifier and returns accept or deny, the value becomes +the result of the expansion. +If no message was set and the ACL returned accept or deny +the value is an empty string. +If the ACL returned defer the result is a forced-fail. Otherwise the expansion fails. + + .vitem "&*${dlfunc{*&<&'file'&>&*}{*&<&'function'&>&*}{*&<&'arg'&>&*}&&& {*&<&'arg'&>&*}...}*&" .cindex &%dlfunc%& @@ -9507,6 +9584,7 @@ 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 &*${domain:*&<&'string'&>&*}*& .cindex "domain" "extraction" .cindex "expansion" "domain extraction" @@ -9666,6 +9744,25 @@ See the description of the general &%length%& item above for details. Note that when &%length%& is used as an operator. +.vitem &*${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 &*${listnamed:*&<&'name'&>&*}*&&~and&~&*${list_*&<&'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 if 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" @@ -9773,10 +9870,8 @@ This operator returns a somewhat random number which is less than the supplied number and is at least 0. The quality of this randomness depends on how Exim was built; the values are not suitable for keying material. If Exim is linked against OpenSSL then RAND_pseudo_bytes() is used. -.new If Exim is linked against GnuTLS then gnutls_rnd(GNUTLS_RND_NONCE) is used, for versions of GnuTLS with that function. -.wen Otherwise, the implementation may be arc4random(), random() seeded by srandomdev() or srandom(), or a custom implementation even weaker than random(). @@ -9955,8 +10050,8 @@ ${if >{$message_size}{10M} ... .endd Note that the general negation operator provides for inequality testing. The two strings must take the form of optionally signed decimal integers, -optionally followed by one of the letters &"K"& or &"M"& (in either upper or -lower case), signifying multiplication by 1024 or 1024*1024, respectively. +optionally followed by one of the letters &"K"&, &"M"& or &"G"& (in either upper or +lower case), signifying multiplication by 1024, 1024*1024 or 1024*1024*1024, respectively. As a special case, the numerical value of an empty string is taken as zero. @@ -9965,6 +10060,21 @@ 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 overwritten. 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" @@ -10182,7 +10292,6 @@ string is lexically greater than the second string. For &%gt%& the comparison includes the case of letters, whereas for &%gti%& the comparison is case-independent. -.new .vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&& &*inlisti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& .cindex "string" "comparison" @@ -10199,7 +10308,6 @@ ${if inlist{needle}{foo:needle:bar}} ${if inlisti{Needle}{fOo:NeeDLE:bAr}} ${if forany{fOo:NeeDLE:bAr}{eqi{$item}{Needle}}} .endd -.wen .vitem &*isip&~{*&<&'string'&>&*}*& &&& &*isip4&~{*&<&'string'&>&*}*& &&& @@ -10311,12 +10419,10 @@ See &*match_local_part*&. .vitem &*match_ip&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& .cindex "&%match_ip%& expansion condition" -.new This condition matches an IP address to a list of IP address patterns. It must be followed by two argument strings. The first (after expansion) must be an IP address or an empty string. The second (not expanded) is a restricted host list that can match only an IP address, not a host name. For example: -.wen .code ${if match_ip{$sender_host_address}{1.2.3.4:5.6.7.8}{...}{...}} .endd @@ -10362,10 +10468,8 @@ just as easy to use the fact that a lookup is itself a condition, and write: .endd .endlist ilist -.new Note that <&'string2'&> is not itself subject to string expansion, unless Exim was built with the EXPAND_LISTMATCH_RHS option. -.wen Consult section &<>& for further details of these patterns. @@ -10394,10 +10498,8 @@ item can be used, as in all address lists, to cause subsequent items to have their local parts matched casefully. Domains are always matched caselessly. -.new Note that <&'string2'&> is not itself subject to string expansion, unless Exim was built with the EXPAND_LISTMATCH_RHS option. -.wen &*Note*&: Host lists are &'not'& supported in this way. This is because hosts have two identities: a name and an IP address, and it is not clear @@ -10744,14 +10846,12 @@ is empty and &$authentication_failed$& is set to &"1"&). Failure includes any negative response to an AUTH command, including (for example) an attempt to use an undefined mechanism. -.new .vitem &$av_failed$& .cindex "content scanning" "AV scanner failure" This variable is available when Exim is compiled with the content-scanning extension. It is set to &"0"& by default, but will be set to &"1"& if any problem occurs with the virus scanner (specified by &%av_scanner%&) during the ACL malware condition. -.wen .vitem &$body_linecount$& .cindex "message body" "line count" @@ -11686,6 +11786,31 @@ 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 +otherwise) then this boolean will have been set true if, and only if, the +resolver library states that the reverse DNS was authenticated data. At all +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 +.endd + +Exim does not perform DNSSEC validation itself, instead leaving that to a +validating resolver (eg, unbound, or bind with suitable configuration). + +Exim does not (currently) check to see if the forward DNS was also secured +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 &$sender_host_name$& .vindex "&$sender_host_name$&" When a message is received from a remote host, this variable contains the @@ -11884,22 +12009,43 @@ command in a filter file. Its use is explained in the description of that command, which can be found in the separate document entitled &'Exim's interfaces to mail filtering'&. -.new -.vitem &$tls_bits$& -.vindex "&$tls_bits$&" -Contains an approximation of the TLS cipher's bit-strength; the meaning of +.vitem &$tls_in_bits$& +.vindex "&$tls_in_bits$&" +Contains an approximation of the TLS cipher's bit-strength +on the inbound connection; the meaning of this depends upon the TLS implementation used. If TLS has not been negotiated, the value will be 0. The value of this is automatically fed into the Cyrus SASL authenticator when acting as a server, to specify the "external SSF" (a SASL term). -.wen -.vitem &$tls_certificate_verified$& -.vindex "&$tls_certificate_verified$&" +The deprecated &$tls_bits$& variable refers to the inbound side +except when used in the context of an outbound SMTP delivery, when it refers to +the outbound. + +.vitem &$tls_out_bits$& +.vindex "&$tls_out_bits$&" +Contains an approximation of the TLS cipher's bit-strength +on an outbound SMTP connection; the meaning of +this depends upon the TLS implementation used. +If TLS has not been negotiated, the value will be 0. + +.vitem &$tls_in_certificate_verified$& +.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 @@ -11908,24 +12054,39 @@ 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. -.new -.vitem &$tls_sni$& +The deprecated &$tls_peerdn$& variable refers to the inbound side +except when used in the context of an outbound SMTP delivery, when it refers to +the outbound. + +.vitem &$tls_out_peerdn$& +.vindex "&$tls_out_peerdn$&" +When a message is being delivered to a remote host over an encrypted SMTP +connection, and Exim is configured to request a certificate from the server, +the value of the Distinguished Name of the certificate is made available in the +&$tls_out_peerdn$& during subsequent processing. + +.vitem &$tls_in_sni$& +.vindex "&$tls_in_sni$&" .vindex "&$tls_sni$&" .cindex "TLS" "Server Name Indication" When a TLS session is being established, if the client sends the Server @@ -11936,10 +12097,16 @@ will be re-expanded early in the TLS session, to permit a different certificate to be presented (and optionally a different key to be used) to the client, based upon the value of the SNI extension. -The value will be retained for the lifetime of the message. During outbound -SMTP deliveries, it reflects the value of the &%tls_sni%& option on +The deprecated &$tls_sni$& variable refers to the inbound side +except when used in the context of an outbound SMTP delivery, when it refers to +the outbound. + +.vitem &$tls_out_sni$& +.vindex "&$tls_out_sni$&" +.cindex "TLS" "Server Name Indication" +During outbound +SMTP deliveries, this variable reflects the value of the &%tls_sni%& option on the transport. -.wen .vitem &$tod_bsdinbox$& .vindex "&$tod_bsdinbox$&" @@ -12690,6 +12857,9 @@ listed in more than one group. .section "TLS" "SECID108" .table2 .row &%gnutls_compat_mode%& "use GnuTLS compatibility mode" +.new +.row &%gnutls_enable_pkcs11%& "allow GnuTLS to autoload PKCS11 modules" +.wen .row &%openssl_options%& "adjust OpenSSL compatibility options" .row &%tls_advertise_hosts%& "advertise TLS to these hosts" .row &%tls_certificate%& "location of server certificate" @@ -12839,6 +13009,9 @@ See also the &'Policy controls'& section above. .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" @@ -12883,7 +13056,6 @@ See also the &'Policy controls'& section above. Those options that undergo string expansion before use are marked with †. -.new .option accept_8bitmime main boolean true .cindex "8BITMIME" .cindex "8-bit characters" @@ -12899,7 +13071,6 @@ A more detailed analysis of the issues is provided by Dan Bernstein: .display &url(http://cr.yp.to/smtp/8bitmime.html) .endd -.wen .option acl_not_smtp main string&!! unset .cindex "&ACL;" "for non-SMTP messages" @@ -13080,10 +13251,10 @@ 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. @@ -13482,6 +13653,17 @@ 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" @@ -13491,7 +13673,6 @@ the system default. A value of 0 coerces EDNS0 off, a value of 1 coerces EDNS0 on. If the resolver library does not support EDNS0 then this option has no effect. -.wen .option drop_cr main boolean false @@ -13707,6 +13888,19 @@ 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. + +.new +option gnutls_enable_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.gnu.org/software/gnutls/manual/gnutls.html#Smart-cards-and-HSMs) +for documentation. +.wen + + + .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 @@ -14385,7 +14579,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. -.option openssl_options main "string list" unset +.option openssl_options main "string list" "+no_sslv2" .cindex "OpenSSL "compatibility options" This option allows an administrator to adjust the SSL options applied by OpenSSL to connections. It is given as a space-separated list of items, @@ -14405,12 +14599,10 @@ yourself in the foot in various unpleasant ways. This option should not be adjusted lightly. An unrecognised item will be detected at startup, by invoking Exim with the &%-bV%& flag. -.new Historical note: prior to release 4.80, Exim defaulted this value to "+dont_insert_empty_fragments", which may still be needed for compatibility with some clients, but which lowers security by increasing exposure to some now infamous attacks. -.wen An example: .code @@ -14800,7 +14992,7 @@ 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}}\ @@ -15044,7 +15236,7 @@ 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 &&& +.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" @@ -15663,12 +15855,10 @@ receiving incoming messages as a server. If you want to supply certificates for use when sending messages as a client, you must set the &%tls_certificate%& option in the relevant &(smtp)& transport. -.new -If the option contains &$tls_sni$& and Exim is built against OpenSSL, then +If the option contains &$tls_out_sni$& and Exim is built against OpenSSL, then if the OpenSSL build supports TLS extensions and the TLS client sends the Server Name Indication extension, then this option and others documented in &<>& will be re-expanded. -.wen .option tls_crl main string&!! unset .cindex "TLS" "server certificate revocation list" @@ -15676,12 +15866,9 @@ Server Name Indication extension, then this option and others documented in This option specifies a certificate revocation list. The expanded value must be the name of a file that contains a CRL in PEM format. -.new See &<>& for discussion of when this option might be re-expanded. -.wen -.new .option tls_dh_max_bits main integer 2236 .cindex "TLS" "D-H bit count" The number of bits used for Diffie-Hellman key-exchange may be suggested by @@ -15697,20 +15884,50 @@ by Thunderbird, while GnuTLS was suggesting 2432 bits as normal. If you prefer more security and are willing to break some clients, raise this number. -.wen + +Note that the value passed to GnuTLS for *generating* a new prime may be a +little less than this figure, because GnuTLS is inexact and may produce a +larger prime than requested. .option tls_dhparam main string&!! unset .cindex "TLS" "D-H parameters for server" -The value of this option is expanded, and must then be the absolute path to -a file which contains the server's DH parameter values. -This is used only for OpenSSL. When Exim is linked with GnuTLS, this option is -ignored. See section &<>& for further details. +The value of this option is expanded and indicates the source of DH parameters +to be used by Exim. -.new -If the DH bit-count from loading the file is greater than tls_dh_max_bits then -it will be ignored. -.wen +If it is a filename starting with a &`/`&, then it names a file from which DH +parameters should be loaded. If the file exists, it should hold a PEM-encoded +PKCS#3 representation of the DH prime. If the file does not exist, for +OpenSSL it is an error. For GnuTLS, Exim will attempt to create the file and +fill it with a generated DH prime. For OpenSSL, if the DH bit-count from +loading the file is greater than &%tls_dh_max_bits%& then it will be ignored, +and treated as though the &%tls_dhparam%& were set to "none". + +If this option expands to the string "none", then no DH parameters will be +loaded by Exim. + +If this option expands to the string "historic" and Exim is using GnuTLS, then +Exim will attempt to load a file from inside the spool directory. If the file +does not exist, Exim will attempt to create it. +See section &<>& for further details. + +If Exim is using OpenSSL and this option is empty or unset, then Exim will load +a default DH prime; the default is the 2048 bit prime described in section +2.2 of RFC 5114, "2048-bit MODP Group with 224-bit Prime Order Subgroup", which +in IKE is assigned number 23. + +Otherwise, the option must expand to the name used by Exim for any of a number +of DH primes specified in RFC 2409, RFC 3526 and RFC 5114. As names, Exim uses +"ike" followed by the number used by IKE, of "default" which corresponds to +"ike23". + +The available primes are: +&`ike1`&, &`ike2`&, &`ike5`&, +&`ike14`&, &`ike15`&, &`ike16`&, &`ike17`&, &`ike18`&, +&`ike22`&, &`ike23`& (aka &`default`&) and &`ike24`&. + +Some of these will be too small to be accepted by clients. +Some may be too large to be accepted by clients. .option tls_on_connect_ports main "string list" unset @@ -15729,9 +15946,7 @@ the expansion is forced to fail, or the result is an empty string, the private key is assumed to be in the same file as the server's certificates. See chapter &<>& for further details. -.new See &<>& for discussion of when this option might be re-expanded. -.wen .option tls_remember_esmtp main boolean false @@ -15779,9 +15994,7 @@ connecting clients, defining the list of accepted certificate authorities. Thus the values defined should be considered public data. To avoid this, use OpenSSL with a directory. -.new See &<>& for discussion of when this option might be re-expanded. -.wen .option tls_verify_hosts main "host list&!!" unset @@ -16120,7 +16333,7 @@ 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 @@ -16319,6 +16532,9 @@ The &%headers_add%& option is expanded after &%errors_to%&, but before the expansion is forced to fail, the option 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. @@ -16352,6 +16568,9 @@ The &%headers_remove%& option is expanded after &%errors_to%& and the option 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. @@ -17103,7 +17322,6 @@ look for A or AAAA records, unless the domain matches &%mx_domains%&, in which case routing fails. -.new .section "Declining addresses by dnslookup" "SECTdnslookupdecline" .cindex "&(dnslookup)& router" "declines" There are a few cases where a &(dnslookup)& router will decline to accept @@ -17134,7 +17352,6 @@ The domain is not syntactically valid (see also &%allow_utf8_domains%& and &%check_secondary_mx%& is set on this router but the local host can not be found in the MX records (see below) .endlist -.wen @@ -18360,6 +18577,18 @@ 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 +quotes will be used by the configuration parser to define the extent of one +string, but will not be passed down into the redirect router itself. There +are two main approaches to get around this: escape quotes to be part of the +data itself, or avoid using this mechanism and instead create a custom +transport with the &%command%& option set and reference that transport from +an &%accept%& router. +.wen + .next .cindex "file" "in redirection list" .cindex "address redirection" "to file" @@ -19345,6 +19574,9 @@ 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 @@ -19367,6 +19599,9 @@ 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_remove%& can be specified multiple times +for a router; all listed headers are added. + .option headers_rewrite transports string unset @@ -20255,7 +20490,6 @@ This option applies only to deliveries in maildir format, and is described in section &<>& below. -.new .option maildir_use_size_file appendfile&!! boolean false .cindex "maildir format" "&_maildirsize_& file" The result of string expansion for this option must be a valid boolean value. @@ -20264,7 +20498,6 @@ creates a &_maildirsize_& file in a maildir if one does not exist, taking the quota from the &%quota%& option of the transport. If &%quota%& is unset, the value is zero. See &%maildir_quota_directory_regex%& above and section &<>& below for further details. -.wen .option maildirfolder_create_regex appendfile string unset .cindex "maildir format" "&_maildirfolder_& file" @@ -21913,6 +22146,9 @@ 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" @@ -21950,7 +22186,7 @@ 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 @@ -22046,6 +22282,22 @@ See the &%search_parents%& option in chapter &<>& for more details. +.new +.option dscp smtp string&!! unset +.cindex "DCSP" "outbound" +This option causes the DSCP value associated with a socket to be set to one +of a number of fixed strings or to numeric value. +The &%-bI:dscp%& option may be used to ask Exim which names it knows of. +Common values include &`throughput`&, &`mincost`&, and on newer systems +&`ef`&, &`af41`&, etc. Numeric values may be in the range 0 to 0x3F. + +The outbound packets from Exim will be marked with this value in the header +(for IPv4, the TOS field; for IPv6, the TCLASS field); there is no guarantee +that these values will have any effect, not be stripped by networking +equipment, or do much of anything without cooperation with your Network +Engineer and those of all network operators between the source and destination. +.wen + .option fallback_hosts smtp "string list" unset .cindex "fallback" "hosts specified on transport" @@ -22179,6 +22431,13 @@ 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" @@ -22356,12 +22615,10 @@ protocol (RFC 2033) instead of SMTP. This protocol is sometimes used for local deliveries into closed message stores. Exim also has support for running LMTP over a pipe to a local process &-- see chapter &<>&. -.new If this option is set to &"smtps"&, the default vaule for the &%port%& option changes to &"smtps"&, and the transport initiates TLS immediately after connecting, as an outbound SSL-on-connect, instead of using STARTTLS to upgrade. The Internet standards bodies strongly discourage use of this mode. -.wen .option retry_include_ip_address smtp boolean true @@ -22445,6 +22702,19 @@ 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 +key agreement is negotiated, the server will provide a large prime number +for use. This option establishes the minimum acceptable size of that number. +If the parameter offered by the server is too small, then the TLS handshake +will fail. + +Only supported when using GnuTLS. +.wen + + .option tls_privatekey smtp string&!! unset .cindex "TLS" "client private key, location of" .vindex "&$host$&" @@ -22474,19 +22744,19 @@ ciphers is a preference order. -.new .option tls_sni smtp string&!! unset .cindex "TLS" "Server Name Indication" .vindex "&$tls_sni$&" -If this option is set then it sets the $tls_sni variable and causes any +If this option is set then it sets the $tls_out_sni variable and causes any TLS session to pass this value as the Server Name Indication extension to the remote side, which can be used by the remote side to select an appropriate certificate and private key for the session. See &<>& for more information. -OpenSSL only, also requiring a build of OpenSSL that supports TLS extensions. -.wen +Note that for OpenSSL, this feature requires a build of OpenSSL that supports +TLS extensions. + @@ -23665,18 +23935,15 @@ included by setting .code AUTH_CRAM_MD5=yes AUTH_CYRUS_SASL=yes -.new AUTH_DOVECOT=yes AUTH_GSASL=yes AUTH_HEIMDAL_GSSAPI=yes -.wen AUTH_PLAINTEXT=yes AUTH_SPA=yes .endd in &_Local/Makefile_&, respectively. The first of these supports the CRAM-MD5 authentication mechanism (RFC 2195), and the second provides an interface to the Cyrus SASL authentication library. -.new The third is an interface to Dovecot's authentication system, delegating the work via a socket interface. The fourth provides an interface to the GNU SASL authentication library, which @@ -23687,7 +23954,6 @@ The sixth can be configured to support the PLAIN authentication mechanism (RFC 2595) or the LOGIN mechanism, which is not formally documented, but used by several MUAs. The seventh authenticator supports Microsoft's &'Secure Password Authentication'& mechanism. -.wen The authenticators are configured using the same syntax as other drivers (see section &<>&). If no authenticators are required, no @@ -23719,7 +23985,6 @@ The remainder of this chapter covers the generic options for the authenticators, followed by general discussion of the way authentication works in Exim. -.new &*Beware:*& the meaning of &$auth1$&, &$auth2$&, ... varies on a per-driver and per-mechanism basis. Please read carefully to determine which variables hold account labels such as usercodes and which hold passwords or other @@ -23741,7 +24006,6 @@ A &'realm'& is a text string, typically a domain name, presented by a server to a client to help it select an account and credentials to use. In some mechanisms, the client and server provably agree on the realm, but clients typically can not treat the realm as secure data to be blindly trusted. -.wen @@ -23755,11 +24019,8 @@ 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 driver authenticators string unset @@ -23789,10 +24050,8 @@ This option must be set for a &%plaintext%& server authenticator, where it is used directly to control authentication. See section &<>& for details. -.new For the &(gsasl)& authenticator, this option is required for various mechanisms; see chapter &<>& for details. -.wen For the other authenticators, &%server_condition%& can be used as an additional authentication or authorization mechanism that is applied after the other @@ -23921,10 +24180,10 @@ 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 @@ -24399,7 +24658,6 @@ lookup_cram: Note that this expansion explicitly forces failure if the lookup fails because &$auth1$& contains an unknown user name. -.new As another example, if you wish to re-use a Cyrus SASL sasldb2 file without using the relevant libraries, you need to know the realm to specify in the lookup and then ask for the &"userPassword"& attribute for that user in that @@ -24412,7 +24670,6 @@ cyrusless_crammd5: dbmjz{/etc/sasldb2}} server_set_id = $auth1 .endd -.wen .section "Using cram_md5 as a client" "SECID177" .cindex "options" "&(cram_md5)& authenticator (client)" @@ -24487,7 +24744,7 @@ Kerberos, note that because of limitations in the GSSAPI interface, changing the server keytab might need to be communicated down to the Kerberos layer independently. The mechanism for doing so is dependent upon the Kerberos implementation. -.new + For example, for older releases of Heimdal, the environment variable KRB5_KTNAME may be set to point to an alternative keytab file. Exim will pass this variable through from its own inherited environment when started as root or the @@ -24496,7 +24753,6 @@ With newer releases of Heimdal, a setuid Exim may cause Heimdal to discard the environment variable. In practice, for those releases, the Cyrus authenticator is not a suitable interface for GSSAPI (Kerberos) support. Instead, consider the &(heimdal_gssapi)& authenticator, described in chapter &<>& -.wen .section "Using cyrus_sasl as a server" "SECID178" @@ -24527,10 +24783,8 @@ sasl: server_set_id = $auth1 .endd -.new .option server_realm cyrus_sasl string&!! unset This specifies the SASL realm that the server claims to be in. -.wen .option server_service cyrus_sasl string &`smtp`& @@ -24603,7 +24857,6 @@ who authenticated is placed in &$auth1$&. . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.new .chapter "The gsasl authenticator" "CHAPgsasl" .scindex IIDgsaslauth1 "&(gsasl)& authenticator" .scindex IIDgsaslauth2 "authenticators" "&(gsasl)&" @@ -24758,12 +25011,10 @@ gsasl_cyrusless_crammd5: server_condition = yes .endd -.wen . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.new .chapter "The heimdal_gssapi authenticator" "CHAPheimdalgss" .scindex IIDheimdalgssauth1 "&(heimdal_gssapi)& authenticator" .scindex IIDheimdalgssauth2 "authenticators" "&(heimdal_gssapi)&" @@ -24810,7 +25061,6 @@ authentication. If that was empty, this will also be set to the GSS Display Name. .endlist -.wen . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -24996,18 +25246,13 @@ There are some differences in usage when using GnuTLS instead of OpenSSL: The &%tls_verify_certificates%& option must contain the name of a file, not the name of a directory (for OpenSSL it can be either). .next -The &%tls_dhparam%& option is ignored, because early versions of GnuTLS had no -facility for varying its Diffie-Hellman parameters. -.new -Since then, the GnuTLS support has been updated to generate parameters upon -demand, keeping them in the spool directory. See &<>& for -details. -.wen +The default value for &%tls_dhparam%& differs for historical reasons. .next -.vindex "&$tls_peerdn$&" +.vindex "&$tls_in_peerdn$&" +.vindex "&$tls_out_peerdn$&" Distinguished Name (DN) strings reported by the OpenSSL library use a slash for separating fields; GnuTLS uses commas, in accordance with RFC 2253. This -affects the value of the &$tls_peerdn$& variable. +affects the value of the &$tls_in_peerdn$& and &$tls_out_peerdn$& variables. .next OpenSSL identifies cipher suites using hyphens as separators, for example: DES-CBC3-SHA. GnuTLS historically used underscores, for example: @@ -25020,18 +25265,28 @@ option). .next 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 explicitly state that the feature is infeasible in the other TLS implementation, then patches are welcome. -.wen .endlist .section "GnuTLS parameter computation" "SECTgnutlsparam" -.new +This section only applies if &%tls_dhparam%& is set to &`historic`& or to +an explicit path; if the latter, then the text about generation still applies, +but not the chosen filename. +By default, as of Exim 4.80 a hard-coded D-H prime is used. +See the documentation of &%tls_dhparam%& for more information. + GnuTLS uses D-H parameters that may take a substantial amount of time to compute. It is unreasonable to re-compute them for every TLS session. Therefore, Exim keeps this data in a file in its spool directory, called @@ -25047,6 +25302,10 @@ place, new Exim processes immediately start using it. For maximum security, the parameters that are stored in this file should be recalculated periodically, the frequency depending on your paranoia level. +If you are avoiding using the fixed D-H primes published in RFCs, then you +are concerned about some advanced attacks and will wish to do this; if you do +not regenerate then you might as well stick to the standard primes. + Arranging this is easy in principle; just delete the file when you want new values to be computed. However, there may be a problem. The calculation of new parameters needs random numbers, and these are obtained from &_/dev/random_&. @@ -25070,6 +25329,10 @@ renaming. The relevant commands are something like this: # chown exim:exim new-params # chmod 0600 new-params # certtool --generate-dh-params --bits 2236 >>new-params +# openssl dhparam -noout -text -in new-params | head +[ check the first line, make sure it's not more than 2236; + if it is, then go back to the start ("rm") and repeat + until the size generated is at most the size requested ] # chmod 0400 new-params # mv new-params gnutls-params-2236 .endd @@ -25092,7 +25355,12 @@ The filename and bits used will change as the GnuTLS maintainers change the value for their parameter &`GNUTLS_SEC_PARAM_NORMAL`&, as clamped by &%tls_dh_max_bits%&. At the time of writing (mid 2012), GnuTLS 2.12 recommends 2432 bits, while NSS is limited to 2236 bits. -.wen + +In fact, the requested value will be *lower* than &%tls_dh_max_bits%&, to +increase the chance of the generated prime actually being within acceptable +bounds, as GnuTLS has been observed to overshoot. Note the check step in the +procedure above. There is no sane procedure available to Exim to double-check +the size of the generated prime, so it might still be too large. .section "Requiring specific ciphers in OpenSSL" "SECTreqciphssl" @@ -25142,7 +25410,6 @@ includes any ciphers already present they will be ignored: that is, they will not be moved to the end of the list. .endlist -.new The OpenSSL &'ciphers(1)'& command may be used to test the results of a given string: .code @@ -25160,11 +25427,9 @@ tls_require_ciphers = ${if =={$received_port}{25}\ {DEFAULT}\ {HIGH:!MD5:!SHA1}} .endd -.wen -.new .section "Requiring specific ciphers or other parameters in GnuTLS" &&& "SECTreqciphgnu" .cindex "GnuTLS" "specifying parameters for" @@ -25210,7 +25475,6 @@ tls_require_ciphers = ${if =={$received_port}{25}\ {NORMAL:%COMPAT}\ {SECURE128}} .endd -.wen .section "Configuring an Exim server to use TLS" "SECID182" @@ -25270,13 +25534,22 @@ this). There is one other option that may be needed in other situations. If tls_dhparam = /some/file/name .endd is set, the SSL library is initialized for the use of Diffie-Hellman ciphers -with the parameters contained in the file. This increases the set of cipher -suites that the server supports. See the command +with the parameters contained in the file. +Set this to &`none`& to disable use of DH entirely, by making no prime +available: +.code +tls_dhparam = none +.endd +This may also be set to a string identifying a standard prime to be used for +DH; if it is set to &`default`& or, for OpenSSL, is unset, then the prime +used is &`ike23`&. There are a few standard primes available, see the +documetnation for &%tls_dhparam%& for the complete list. + +See the command .code openssl dhparam .endd -for a way of generating this data. At present, &%tls_dhparam%& is used only -when Exim is linked with OpenSSL. It is ignored if GnuTLS is being used. +for a way of generating file data. The strings supplied for these three options are expanded every time a client host connects. It is therefore possible to use different certificates and keys @@ -25286,15 +25559,13 @@ 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 @@ -25303,6 +25574,9 @@ 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" @@ -25339,17 +25613,17 @@ 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" @@ -25430,12 +25704,12 @@ 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 @@ -25443,11 +25717,10 @@ outgoing connection. -.new .section "Use of TLS Server Name Indication" "SECTtlssni" .cindex "TLS" "Server Name Indication" -.vindex "&$tls_sni$&" -.oindex "&%tls_sni%&" +.vindex "&$tls_in_sni$&" +.oindex "&%tls_in_sni%&" With TLS1.0 or above, there is an extension mechanism by which extra information can be included at various points in the protocol. One of these extensions, documented in RFC 6066 (and before that RFC 4366) is @@ -25474,14 +25747,14 @@ 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: @@ -25515,7 +25788,6 @@ see &`-servername`& in the output, then OpenSSL has support. When Exim is built against GnuTLS, SNI support is available as of GnuTLS 0.5.10. (Its presence predates the current API which Exim uses, so if Exim built, then you have SNI support). -.wen @@ -26496,7 +26768,7 @@ 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 @@ -26713,6 +26985,46 @@ Notice that we put back the lower cased version afterwards, assuming that is what is wanted for subsequent tests. +.new +.vitem &*control&~=&~cutthrough_delivery*& +.cindex "&ACL;" "cutthrough routing" +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. + +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. +.wen + + +.new +.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. +.wen + + .vitem &*control&~=&~debug/*&<&'options'&> .cindex "&ACL;" "enabling debug logging" .cindex "debugging" "enabling from an ACL" @@ -27033,6 +27345,7 @@ 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 @@ -27042,6 +27355,10 @@ 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 in $acl_arg1 to $acl_arg9, and $acl_narg is set +to the count of values. 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 @@ -28800,16 +29117,16 @@ 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 @@ -31176,6 +31493,10 @@ headers_add = X-added-header: added by $primary_hostname\n\ .endd Exim does not check the syntax of these added header lines. +Multiple &%headers_add%& options for a single router or transport can be +specified; the values will be concatenated (with a separating newline +added) before expansion. + The result of expanding &%headers_remove%& 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, @@ -31183,6 +31504,11 @@ not part of the names. For example: .code headers_remove = return-receipt-to:acknowledge-to .endd + +Multiple &%headers_remove%& options for a single router or transport can be +specified; the values will be concatenated (with a separating colon +added) before expansion. + 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 accepted by that router, and also with any new addresses that it generates. If @@ -31421,6 +31747,8 @@ 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 @@ -33363,7 +33691,7 @@ 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_no_mail `& session with no MAIL commands