X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/5a1a584503da8218be7759637e7caa1cb169e1a7..4b2241d2228351057f63f954de46b0449288e3ba:/doc/doc-docbook/spec.xfpt?ds=sidebyside diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index cba865032..7a9698e57 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -1,4 +1,4 @@ -. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.71 2010/03/05 16:08:14 nm4 Exp $ +. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.82 2010/06/06 02:08:50 pdp Exp $ . . ///////////////////////////////////////////////////////////////////////////// . This is the primary source of the Exim Manual. It is an xfpt document that is @@ -47,8 +47,8 @@ . the element must also be updated for each new edition. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.69" -.set version "4.71" +.set previousversion "4.71" +.set version "4.72" .set ACL "access control lists (ACLs)" .set I "    " @@ -172,12 +172,12 @@ Specification of the Exim Mail Transfer Agent The Exim MTA -5 November 2009 +29 May 2010 EximMaintainers EM - 4.71 - 5 November 2009 + 4.72 + 29 May 2010 EM 2009University of Cambridge @@ -2604,6 +2604,11 @@ This option causes Exim to output a few sentences stating what it is. The same output is generated if the Exim binary is called with no options and no arguments. +.vitem &%--version%& +.oindex "&%--version%&" +This option is an alias for &%-bV%& and causes version information to be +displayed. + .vitem &%-B%&<&'type'&> .oindex "&%-B%&" .cindex "8-bit characters" @@ -3169,6 +3174,17 @@ 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. Exim will +have changed working directory before resolving the filename, so using fully +qualified pathnames is advisable. This option requires admin privileges. + .vitem &%-bt%& .oindex "&%-bt%&" .cindex "testing" "addresses" @@ -3745,7 +3761,7 @@ written to the standard output. This option can be used only by an admin user. .vitem &%-Mvc%&&~<&'message&~id'&> .oindex "&%-Mvc%&" .cindex "message" "listing in RFC 2822 format" -.cindex "listing" "message in RFC 2922 format" +.cindex "listing" "message in RFC 2822 format" This option causes a copy of the complete message (header lines plus body) to be written to the standard output in RFC 2822 format. This option can be used only by an admin user. @@ -6628,6 +6644,20 @@ ${lookup dnsdb{>: a=host1.example}} It is permitted to specify a space as the separator character. Further white space is ignored. +.new +.cindex "TXT record" "in &(dnsdb)& lookup" +For TXT records with multiple items of data, only the first item is returned, +unless a separator for them is specified using a comma after the separator +character followed immediately by the TXT record item separator. To concatenate +items without a separator, use a semicolon instead. +.code +${lookup dnsdb{>\n,: txt=a.b.example}} +${lookup dnsdb{>\n; txt=a.b.example}} +.endd +It is permitted to specify a space as the separator character. Further +white space is ignored. +.wen + .section "Pseudo dnsdb record types" "SECID66" .cindex "MX record" "in &(dnsdb)& lookup" By default, both the preference value and the host name are returned for @@ -9590,6 +9620,21 @@ srandomdev() or srandom(), or a custom implementation even weaker than random(). +.vitem &*${reverse_ip:*&<&'ipaddr'&>&*}*& +.cindex "expansion" "IP address" +This operator reverses an IP address; for IPv4 addresses, the result is in +dotted-quad decimal form, while for IPv6 addreses the result is in +dotted-nibble hexadecimal form. In both cases, this is the "natural" form +for DNS. For example, +.code +${reverse_ip:192.0.2.4} and ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3} +.endd +returns +.code +4.2.0.192 and 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2 +.endd + + .vitem &*${rfc2047:*&<&'string'&>&*}*& .cindex "expansion" "RFC 2047" .cindex "RFC 2047" "expansion operator" @@ -9762,7 +9807,7 @@ All other string values will result in expansion failure. When combined with ACL variables, this expansion condition will let you make decisions in one place and act on those decisions in another place. -For example, +For example: .code ${if bool{$acl_m_privileged_sender} ... .endd @@ -12323,6 +12368,7 @@ 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_dkim%& "ACL for DKIM verification" .row &%acl_smtp_etrn%& "ACL for ETRN" .row &%acl_smtp_expn%& "ACL for EXPN" .row &%acl_smtp_helo%& "ACL for EHLO or HELO" @@ -12378,6 +12424,7 @@ listed in more than one group. .row &%gnutls_require_mac%& "control GnuTLS MAC algorithms" .row &%gnutls_require_protocols%& "control GnuTLS protocols" .row &%gnutls_compat_mode%& "use GnuTLS compatibility mode" +.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" @@ -12783,7 +12830,7 @@ It specifies which anti-virus scanner to use. The default value is: .code sophie:/var/run/sophie .endd -If the value of &%av_scanner%& starts with dollar character, it is expanded +If the value of &%av_scanner%& starts with a dollar character, it is expanded before use. See section &<>& for further details. @@ -13937,6 +13984,14 @@ an oversized message is logged in both the main and the reject logs. See also the generic transport option &%message_size_limit%&, which limits the size of message that an individual transport can process. +If you use a virus-scanner and set this option to to a value larger than the +maximum size that your virus-scanner is configured to support, you may get +failures triggered by large mails. The right size to configure for the +virus-scanner depends upon what data is passed and the options in use but it's +probably safest to just set it to a little larger than this value. Eg, with a +default Exim message size of 50M and a default ClamAV StreamMaxLength of 10M, +some problems may result. + .option move_frozen_messages main boolean false .cindex "frozen messages" "moving" @@ -13989,6 +14044,36 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. +.option openssl_options main "string list" +dont_insert_empty_fragments +.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, +each one to be +added or -subtracted from the current value. The default +value is one option which happens to have been set historically. You can +remove all options with: +.code +openssl_options = -all +.endd +This option is only available if Exim is built against OpenSSL. The values +available for this option vary according to the age of your OpenSSL install. +The &"all"& value controls a subset of flags which are available, typically +the bug workaround options. The &'SSL_CTX_set_options'& man page will +list the values known on your system and Exim should support all the +&"bug workaround"& options and many of the &"modifying"& options. The Exim +names lose the leading &"SSL_OP_"& and are lower-cased. + +Note that adjusting the options can have severe impact upon the security of +SSL as used by Exim. It is possible to disable safety checks and shoot +yourself in the foot in various unpleasant ways. This option should not be +adjusted lightly. An unrecognised item will be detected at by invoking Exim +with the &%-bV%& flag. + +An example: +.code +openssl_options = -all +microsoft_big_sslv3_buffer +.endd + + .option oracle_servers main "string list" unset .cindex "Oracle" "server list" This option provides a list of Oracle servers and associated connection data, @@ -21030,6 +21115,17 @@ sought in the PATH directories, in the usual way. &*Warning*&: This does not apply to a command specified as a transport filter. +.option permit_coredump pipe boolean false +Normally Exim inhibits core-dumps during delivery. If you have a need to get +a core-dump of a pipe command, enable this command. This enables core-dumps +during delivery and affects both the Exim binary and the pipe command run. +It is recommended that this option remain off unless and until you have a need +for it and that this only be enabled when needed, as the risk of excessive +resource consumption can be quite high. Note also that Exim is typically +installed as a setuid binary and most operating systems will inhibit coredumps +of these by default, so further OS-specific action may be required. + + .option pipe_as_creator pipe boolean false .cindex "uid (user id)" "local delivery" If the generic &%user%& option is not set and this option is true, the delivery @@ -21170,6 +21266,7 @@ procmail_pipe: envelope_to_add check_string = "From " escape_string = ">From " + umask = 077 user = $local_part group = mail @@ -25681,6 +25778,23 @@ warn control = caseful_local_part Notice that we put back the lower cased version afterwards, assuming that is what is wanted for subsequent tests. +.vitem &*control&~=&~debug/*&<&'options'&> +.cindex "&ACL;" "enabling debug logging" +.cindex "debugging" "enabling from an ACL" +This control turns on debug logging, almost as though Exim had been invoked +with &`-d`&, with the output going to a new logfile, by default called +&'debuglog'&. The filename can be adjusted with the &'tag'& option, which +may access any variables already defined. The logging may be adjusted with +the &'opts'& option, which takes the same values as the &`-d`& command-line +option. Some examples (which depend on variables that don't exist in all +contexts): +.code + control = debug + control = debug/tag=.$sender_host_address + control = debug/opts=+expand+acl + control = debug/tag=.$message_exim_id/opts=+expand +.endd + .vitem &*control&~=&~enforce_sync*& &&& &*control&~=&~no_enforce_sync*& .cindex "SMTP" "synchronization checking" @@ -27803,7 +27917,7 @@ If you do not set &%av_scanner%&, it defaults to .code av_scanner = sophie:/var/run/sophie .endd -If the value of &%av_scanner%& starts with dollar character, it is expanded +If the value of &%av_scanner%& starts with a dollar character, it is expanded before use. The following scanner types are supported in this release: .vlist @@ -27827,8 +27941,16 @@ required: either the path and name of a UNIX socket file, or a hostname or IP number, and a port, separated by space, as in the second of these examples: .code av_scanner = clamd:/opt/clamd/socket -av_scanner = clamd:192.168.2.100 1234 -.endd +av_scanner = clamd:192.0.2.3 1234 +av_scanner = clamd:192.0.2.3 1234:local +.endd +If the value of av_scanner points to a UNIX socket file or contains the local +keyword, then the ClamAV interface will pass a filename containing the data +to be scanned, which will should normally result in less I/O happening and be +more efficient. Normally in the TCP case, the data is streamed to ClamAV as +Exim does not assume that there is a common filesystem with the remote host. +There is an option WITH_OLD_CLAMAV_STREAM in &_src/EDITME_& available, should +you be running a version of ClamAV prior to 0.95. If the option is unset, the default is &_/tmp/clamd_&. Thanks to David Saez for contributing the code for this scanner. @@ -27968,6 +28090,9 @@ If your virus scanner cannot unpack MIME and TNEF containers itself, you should use the &%demime%& condition (see section &<>&) before the &%malware%& condition. +Beware the interaction of Exim's &%message_size_limit%& with any size limits +imposed by your anti-virus scanner. + Here is a very simple scanning example: .code deny message = This message contains malware ($malware_name) @@ -28090,9 +28215,8 @@ it always return &"true"& by appending &`:true`& to the username. .cindex "spam scanning" "returned variables" When the &%spam%& condition is run, it sets up a number of expansion -variables. With the exception of &$spam_score_int$&, these are usable only -within ACLs; their values are not retained with the message and so cannot be -used at delivery time. +variables. These variables are saved with the received message, thus they are +available for use at delivery time. .vlist .vitem &$spam_score$& @@ -28103,11 +28227,8 @@ for inclusion in log or reject messages. The spam score of the message, multiplied by ten, as an integer value. For example &"34"& or &"305"&. It may appear to disagree with &$spam_score$& because &$spam_score$& is rounded and &$spam_score_int$& is truncated. -The integer value is useful for numeric comparisons in -conditions. This variable is special; its value is saved with the message, and -written to Exim's spool file. This means that it can be used during the whole -life of the message on your Exim system, in particular, in routers or -transports during the later delivery phase. +The integer value is useful for numeric comparisons in conditions. + .vitem &$spam_bar$& A string consisting of a number of &"+"& or &"-"& characters, representing the @@ -34334,7 +34455,7 @@ It can co-exist with all other Exim features, including transport filters. .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 -different signature context. +different signature contexts. .endlist In typical Exim style, the verification implementation does not include any @@ -34362,19 +34483,19 @@ Signing is implemented by setting private options on the SMTP transport. These options take (expandable) strings as arguments. .option dkim_domain smtp string&!! unset -MANDATORY +MANDATORY: The domain you want to sign with. The result of this expanded option is put into the &%$dkim_domain%& expansion variable. .option dkim_selector smtp string&!! unset -MANDATORY +MANDATORY: This sets the key selector string. You can use the &%$dkim_domain%& expansion variable to look up a matching selector. The result is put in the expansion variable &%$dkim_selector%& which should be used in the &%dkim_private_key%& option along with &%$dkim_domain%&. .option dkim_private_key smtp string&!! unset -MANDATORY +MANDATORY: This sets the private key to use. You can use the &%$dkim_domain%& and &%$dkim_selector%& expansion variables to determine the private key to use. The result can either @@ -34390,14 +34511,14 @@ is set. .endlist .option dkim_canon smtp string&!! unset -OPTIONAL +OPTIONAL: This option sets the canonicalization method used when signing a message. The DKIM RFC currently supports two methods: "simple" and "relaxed". The option defaults to "relaxed" when unset. Note: the current implementation only supports using the same canonicalization method for both headers and body. .option dkim_strict smtp string&!! unset -OPTIONAL +OPTIONAL: This option defines how Exim behaves when signing a message that should be signed fails for some reason. When the expansion evaluates to either "1" or "true", Exim will defer. Otherwise Exim will send the message @@ -34405,7 +34526,7 @@ unsigned. You can use the &%$dkim_domain%& and &%$dkim_selector%& expansion variables here. .option dkim_sign_headers smtp string&!! unset -OPTIONAL +OPTIONAL: When set, this option must expand to (or be specified as) a colon-separated list of header names. Headers with these names will be included in the message signature. When unspecified, the header names recommended in RFC4871 will be @@ -34431,8 +34552,8 @@ more advanced policies. For that reason, the global option The global option &%dkim_verify_signers%& can be set to a colon-separated list of DKIM domains or identities for which the ACL &%acl_smtp_dkim%& is called. It is expanded when the message has been received. At this point, -the expansion variable &%$dkim_signers%& already contains a colon- -separated list of signer domains and identities for the message. When +the expansion variable &%$dkim_signers%& already contains a colon-separated +list of signer domains and identities for the message. When &%dkim_verify_signers%& is not specified in the main configuration, it defaults as: .code @@ -34446,7 +34567,7 @@ dkim_verify_signers = paypal.com:ebay.com:$dkim_signers .endd This would result in &%acl_smtp_dkim%& always being called for "paypal.com" and "ebay.com", plus all domains and identities that have signatures in the message. -You can also be more creative in constructing your policy. Example: +You can also be more creative in constructing your policy. For example: .code dkim_verify_signers = $sender_address_domain:$dkim_signers .endd @@ -34460,7 +34581,7 @@ available (from most to least important): .vlist .vitem &%$dkim_cur_signer%& -The signer that is being evaluated in this ACL run. This can be domain or +The signer that is being evaluated in this ACL run. This can be a domain or an identity. This is one of the list items from the expanded main option &%dkim_verify_signers%& (see above). .vitem &%$dkim_verify_status%& @@ -34505,7 +34626,7 @@ The signing identity, if present. IMPORTANT: This variable is only populated if there is an actual signature in the message for the current domain or identity (as reflected by &%$dkim_cur_signer%&). .vitem &%$dkim_selector%& -The key record selector string +The key record selector string. .vitem &%$dkim_algo%& The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'. .vitem &%$dkim_canon_body%& @@ -34540,7 +34661,7 @@ in the key record. Key granularity (tag g=) from the key record. Defaults to "*" if not specified in the key record. .vitem &%$dkim_key_notes%& -Notes from the key record (tag n=) +Notes from the key record (tag n=). .endlist In addition, two ACL conditions are provided: @@ -34550,7 +34671,7 @@ In addition, two ACL conditions are provided: ACL condition that checks a colon-separated list of domains or identities for a match against the domain or identity that the ACL is currently verifying (reflected by &%$dkim_cur_signer%&). This is typically used to restrict an ACL -verb to a group of domains or identities, like: +verb to a group of domains or identities. For example: .code # Warn when message apparently from GMail has no signature at all