X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/7b2838902b766105e5086e41c0dbb27d87c523ae..c92df897f31aae2f87f69349eda4ad4f295d11b2:/doc/doc-docbook/spec.xfpt?ds=sidebyside diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 00a142a03..5900b9c9e 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -52,7 +52,7 @@ .set I "    " .macro copyyear -2016 +2017 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -434,6 +434,7 @@ directory are: .row &_filter.txt_& "specification of the filter language" .row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3" .row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4" +.row &_openssl.txt_& "installing a current OpenSSL release" .endtable The main specification and the specification of the filtering language are also @@ -4267,7 +4268,7 @@ or &%-bs%& is used. For &%-bh%&, the protocol is forced to one of the standard SMTP protocol names (see the description of &$received_protocol$& in section &<>&). For &%-bs%&, the protocol is always &"local-"& followed by one of those same names. For &%-bS%& (batched SMTP) however, the protocol can -be set by &%-oMr%&. +be set by &%-oMr%&. Repeated use of this option is not supported. .vitem &%-oMs%&&~<&'host&~name'&> .oindex "&%-oMs%&" @@ -4367,6 +4368,7 @@ 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 &`d`& or &`s`& using this option (but that does not seem a real limitation). +Repeated use of this option is not supported. .vitem &%-q%& .oindex "&%-q%&" @@ -4474,12 +4476,12 @@ The name should not contain a &'/'& character. For a periodic queue run (see below) append to the name a slash and a time value. -If other commandline options speicify an action, a &'-qG'& option +If other commandline options specify an action, a &'-qG'& option will specify a queue to operate on. For example: .code exim -bp -qGquarantine -mailq -qGquarantime +mailq -qGquarantine exim -qGoffpeak -Rf @special.domain.example .endd @@ -4918,8 +4920,12 @@ using this syntax: .endd on a line by itself. Double quotes round the file name are optional. If you use the first form, a configuration error occurs if the file does not exist; the -second form does nothing for non-existent files. In all cases, an absolute file +second form does nothing for non-existent files. +.new +The first form allows a relative name. It is resolved relative to +the directory of the including file. For the second form an absolute file name is required. +.wen Includes may be nested to any depth, but remember that Exim reads its configuration file often, so it is a good idea to keep them to a minimum. @@ -6726,8 +6732,8 @@ PostgreSQL database. See section &<>&. .next .cindex "Redis lookup type" .cindex lookup Redis -&(redis)&: The format of the query is an SQL statement that is passed to a -Redis database. See section &<>&. +&(redis)&: The format of the query is either a simple get or simple set, +passed to a Redis database. See section &<>&. .next .cindex "sqlite lookup type" @@ -7105,7 +7111,7 @@ Retries for the dnsdb lookup can be controlled by a retry modifier. The form if &"retry_VAL"& where VAL is an integer. The default count is set by the main configuration option &%dns_retry%&. -.cindex cacheing "of dns lookup" +.cindex caching "of dns lookup" .cindex TTL "of dns lookup" .cindex DNS TTL Dnsdb lookup results are cached within a single process (and its children). @@ -7800,6 +7806,19 @@ are rejected after a timeout period, during which the SQLite library waits for the lock to be released. In Exim, the default timeout is set to 5 seconds, but it can be changed by means of the &%sqlite_lock_timeout%& option. + +.new +.section "More about Redis" "SECTredis" +.cindex "lookup" "Redis" +.cindex "redis lookup type" +Redis is a non-SQL database. Commands are simple get and set. +Examples: +.code +${lookup redis{set keyname ${quote_redis:objvalue plus}}} +${lookup redis{get keyname}} +.endd +.wen + .ecindex IIDfidalo1 .ecindex IIDfidalo2 @@ -9100,7 +9119,7 @@ If the ACL returns defer the result is a forced-fail. Otherwise the expansion f .vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&& {*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&" -.cindex "expansion" "extracting cerificate fields" +.cindex "expansion" "extracting certificate fields" .cindex "&%certextract%&" "certificate fields" .cindex "certificate" "extracting fields" The <&'certificate'&> must be a variable of type certificate. @@ -12205,7 +12224,7 @@ normally the gid of the Exim user. .cindex "uid (user id)" "of originating user" .cindex "sender" "uid" .vindex "&$caller_uid$&" -.vindex "&$originaltor_uid$&" +.vindex "&$originator_uid$&" The value of &$caller_uid$& that was set when the message was received. For messages received via the command line, this is the uid of the sending user. For messages received by SMTP over TCP/IP, this is normally the uid of the Exim @@ -12252,7 +12271,7 @@ qualified host name. See also &$smtp_active_hostname$&. &$proxy_local_port$& &&& &$proxy_session$& These variables are only available when built with Proxy Protocol -or Socks5 support +or SOCKS5 support. For details see chapter &<>&. .vitem &$prdr_requested$& @@ -12602,6 +12621,13 @@ validating resolver (e.g. unbound, or bind with suitable configuration). If you have changed &%host_lookup_order%& so that &`bydns`& is not the first mechanism in the list, then this variable will be false. +.new +This requires that your system resolver library support EDNS0 (and that +DNSSEC flags exist in the system headers). If the resolver silently drops +all EDNS0 options, then this will have no effect. OpenBSD's asr resolver +is known to currently ignore EDNS0, documented in CAVEATS of asr_run(3). +.wen + .vitem &$sender_host_name$& .vindex "&$sender_host_name$&" @@ -12823,7 +12849,7 @@ If TLS has not been negotiated, the value will be 0. .vitem &$tls_in_ourcert$& .vindex "&$tls_in_ourcert$&" -.cindex certificate veriables +.cindex certificate variables 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 @@ -13093,7 +13119,7 @@ initial startup, even if &%perl_at_start%& is set. .oindex "&%perl_taintmode%&" .cindex "Perl" "taintmode" To provide more security executing Perl code via the embedded Perl -interpeter, the &%perl_taintmode%& option can be set. This enables the +interpreter, the &%perl_taintmode%& option can be set. This enables the taint mode of the Perl interpreter. You are encouraged to set this option to a true value. To avoid breaking existing installations, it defaults to false. @@ -13523,6 +13549,7 @@ listed in more than one group. .section "Miscellaneous" "SECID96" .table2 .row &%bi_command%& "to run for &%-bi%& command line option" +.row &%debug_store%& "do extra internal checks" .row &%disable_ipv6%& "do no IPv6 processing" .row &%keep_malformed%& "for broken files &-- should not happen" .row &%localhost_number%& "for unique message ids in clusters" @@ -14013,6 +14040,7 @@ acknowledgment is sent. See chapter &<>& for further details. .option acl_smtp_dkim main string&!! unset .cindex DKIM "ACL for" This option defines the ACL that is run for each DKIM signature +(by default, or as specified in the dkim_verify_signers option) of a received message. See chapter &<>& for further details. @@ -14400,7 +14428,7 @@ it obviously cannot send an error message of any kind. There is a slight performance penalty for these checks. Versions of Exim preceding 4.88 had these disabled by default; -high-rate intallations confident they will never run out of resources +high-rate installations confident they will never run out of resources may wish to deliberately disable them. .option chunking_advertise_hosts main "host list&!!" * @@ -14410,6 +14438,15 @@ The CHUNKING extension (RFC3030) will be advertised in the EHLO message to these hosts. Hosts may use the BDAT command as an alternate to DATA. +.new +.option debug_store main boolean &`false`& +.cindex debugging "memory corruption" +.cindex memory debugging +This option, when true, enables extra checking in Exim's internal memory +management. For use when a memory corruption issue is being investigated, +it should normally be left as default. +.wen + .option daemon_smtp_ports main string &`smtp`& .cindex "port" "for daemon" .cindex "TCP/IP" "setting listening ports" @@ -14659,6 +14696,7 @@ record in the authoritative section is used instead. .option dns_use_edns0 main integer -1 .cindex "DNS" "resolver options" .cindex "DNS" "EDNS0" +.cindex "DNS" "OpenBSD If this option is set to a non-negative number then Exim will initialise the DNS resolver library to either use or not use EDNS0 extensions, overriding the system default. A value of 0 coerces EDNS0 off, a value of 1 coerces EDNS0 @@ -14666,6 +14704,12 @@ on. If the resolver library does not support EDNS0 then this option has no effect. +.new +OpenBSD's asr resolver routines are known to ignore the EDNS0 option; this +means that DNSSEC will not work with Exim on that platform either, unless Exim +is linked against an alternative DNS client library. +.wen + .option drop_cr main boolean false This is an obsolete option that is now a no-op. It used to affect the way Exim @@ -14764,7 +14808,7 @@ not used. .option event_action main string&!! unset .cindex events This option declares a string to be expanded for Exim's events mechanism. -For details see &<>&. +For details see chapter &<>&. .option exim_group main string "compile-time configured" @@ -15115,7 +15159,7 @@ If the &%smtp_connection%& log selector is not set, this option has no effect. .option hosts_proxy main "host list&!!" unset .cindex proxy "proxy protocol" This option enables use of Proxy Protocol proxies for incoming -connections. For details see &<>&. +connections. For details see section &<>&. .option hosts_treat_as_local main "domain list&!!" unset @@ -15289,6 +15333,9 @@ connecting on a regular LDAP port. This is the LDAP equivalent of SMTP's of SSL-on-connect. In the event of failure to negotiate TLS, the action taken is controlled by &%ldap_require_cert%&. +.new +This option is ignored for &`ldapi`& connections. +.wen .option ldap_version main integer unset @@ -15629,7 +15676,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. -.option openssl_options main "string list" "+no_sslv2 +single_dh_use" +.option openssl_options main "string list" "+no_sslv2 +single_dh_use +no_ticket" .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, @@ -16705,7 +16752,7 @@ example, instead of &"Administrative prohibition"&, it might give: .option smtputf8_advertise_hosts main "host list&!!" * .cindex "SMTPUTF8" "advertising" When Exim is built with support for internationalised mail names, -the availability therof is advertised in +the availability thereof is advertised in response to EHLO only to those client hosts that match this option. See chapter &<>& for details of Exim's support for internationalisation. @@ -16862,6 +16909,9 @@ generates any deliveries to files or pipes, or any new mail messages, the appropriate &%system_filter_..._transport%& option(s) must be set, to define which transports are to be used. Details of this facility are given in chapter &<>&. +.new +A forced expansion failure results in no filter operation. +.wen .option system_filter_directory_transport main string&!! unset @@ -20883,7 +20933,7 @@ resent to other recipients. .option event_action transports string&!! unset .cindex events This option declares a string to be expanded for Exim's events mechanism. -For details see &<>&. +For details see chapter &<>&. .option group transports string&!! "Exim group" @@ -20998,7 +21048,7 @@ The control does not apply to shadow transports. .cindex "hints database" "transport concurrency control" Exim implements this control by means of a hints database in which a record is -incremented whenever a transport process is beaing created. The record +incremented whenever a transport process is being created. The record is decremented and possibly removed when the process terminates. Obviously there is scope for records to get left lying around if there is a system or program crash. To @@ -23255,7 +23305,7 @@ message_suffix = &`\n`& to &`\r\n`& in &%message_suffix%&. -.option path pipe string&!! "bin:/usr/bin" +.option path pipe string&!! "/bin:/usr/bin" .new This option is expanded and .wen @@ -23645,7 +23695,7 @@ of the message. Its value must not be zero. See also &%final_timeout%&. .option dkim_canon smtp string&!! unset .option dkim_strict smtp string&!! unset .option dkim_sign_headers smtp string&!! unset -DKIM signing options. For details see &<>&. +DKIM signing options. For details see section &<>&. .option delay_after_cutoff smtp boolean true @@ -23962,12 +24012,12 @@ unauthenticated. See also &%hosts_require_auth%&, and chapter .cindex "RFC 3030" "CHUNKING" This option provides a list of servers to which, provided they announce CHUNKING support, Exim will attempt to use BDAT commands rather than DATA. -BDAT will not be used in conjuction with a transport filter. +BDAT will not be used in conjunction with a transport filter. .option hosts_try_fastopen smtp "host list!!" unset -.option "fast open, TCP" "enabling, in client" -.option "TCP Fast Open" "enabling, in client" -.option "RFC 7413" "TCP Fast Open" +.cindex "fast open, TCP" "enabling, in client" +.cindex "TCP Fast Open" "enabling, in client" +.cindex "RFC 7413" "TCP Fast Open" This option provides a list of servers to which, provided the facility is supported by this system, Exim will attempt to perform a TCP Fast Open. @@ -24151,7 +24201,7 @@ the use of the SIZE option altogether. .option socks_proxy smtp string&!! unset .cindex proxy SOCKS This option enables use of SOCKS proxies for connections made by the -transport. For details see &<>&. +transport. For details see section &<>&. .option tls_certificate smtp string&!! unset @@ -25856,6 +25906,19 @@ turned into a permanent error if you wish. In the second case, Exim tries to deliver the message unauthenticated. .endlist +.new +Note that the hostlist test for whether to do authentication can be +confused if name-IP lookups change between the time the peer is decided +on and the transport running. For example, with a manualroute +router given a host name, and DNS "round-robin" use by that name: if +the local resolver cache times out between the router and the transport +running, the transport may get an IP for the name for its authentication +check which does not match the connection peer IP. +No authentication will then be done, despite the names being identical. + +For such cases use a separate transport which always authenticates. +.wen + .cindex "AUTH" "on MAIL command" When Exim has authenticated itself to a remote server, it adds the AUTH parameter to the MAIL commands it sends, if it has an authenticated sender for @@ -27527,7 +27590,7 @@ Great care should be taken to deal with matters of case, various injection attacks in the string (&`../`& or SQL), and ensuring that a valid filename can always be referenced; it is important to remember that &$tls_in_sni$& is arbitrary unverified data provided prior to authentication. -Further, the initial cerificate is loaded before SNI is arrived, so +Further, the initial certificate is loaded before SNI is arrived, so an expansion for &%tls_certificate%& must have a default which is used when &$tls_in_sni$& is empty. @@ -28071,6 +28134,11 @@ run. A &"discard"& return from the DATA or the non-SMTP ACL discards all the remaining recipients. The &"discard"& return is not permitted for the &%acl_smtp_predata%& ACL. +.new +If the ACL for VRFY returns &"accept"&, a recipient verify (without callout) +is done on the address and the result determines the SMTP response. +.wen + .cindex "&[local_scan()]& function" "when all recipients discarded" The &[local_scan()]& function is always run, even if there are no remaining @@ -28890,7 +28958,11 @@ message body. Cutthrough delivery is not supported via transport-filters or when DKIM signing of outgoing messages is done, because it sends data to the ultimate destination before the entire message has been received from the source. -It is not supported for messages received with the SMTP PRDR option in use. +It is not supported for messages received with the SMTP PRDR +.new +or CHUNKING +.wen +options in use. Should the ultimate destination system positively accept or reject the mail, a corresponding indication is given to the source system and nothing is queued. @@ -28904,7 +28976,7 @@ This behaviour can be adjusted by appending the option &*defer=*&<&'value'&> to the control; the default value is &"spool"& and the alternate value &"pass"& copies an SMTP defer response from the target back to the initiator and does not queue the message. -Note that this is independent of any receipient verify conditions in the ACL. +Note that this is independent of any recipient verify conditions in the ACL. Delivery in this mode avoids the generation of a bounce mail to a (possibly faked) @@ -29128,7 +29200,7 @@ that are being submitted at the same time using &%-bs%& or &%-bS%&. .vitem &*control&~=&~utf8_downconvert*& This control enables conversion of UTF-8 in message addresses to a-label form. -For details see &<>&. +For details see section &<>&. .endlist vlist @@ -29741,6 +29813,15 @@ to avoid doing it more than once per message. .cindex "&%verify%& ACL condition" This is a variation of the previous option, in which a modified address is verified as a sender. + +.new +Note that '/' is legal in local-parts; if the address may have such +(eg. is generated from the received message) +they must be protected from the options parsing by doubling: +.code +verify = sender=${sg{${address:$h_sender:}}{/}{//}} +.endd +.wen .endlist @@ -29800,7 +29881,7 @@ deny dnslists = blackholes.mail-abuse.org warn message = X-Warn: sending host is on dialups list dnslists = dialups.mail-abuse.org .endd -.cindex cacheing "of dns lookup" +.cindex caching "of dns lookup" .cindex DNS TTL DNS list lookups are cached by Exim for the duration of the SMTP session (but limited by the DNS return TTL value), @@ -29913,7 +29994,7 @@ multiple DNS records. The inner dnsdb lookup produces a list of MX hosts and the outer dnsdb lookup finds the IP addresses for these hosts. The result of expanding the condition might be something like this: .code -dnslists = sbl.spahmaus.org/<|192.168.2.3|192.168.5.6|... +dnslists = sbl.spamhaus.org/<|192.168.2.3|192.168.5.6|... .endd Thus, this example checks whether or not the IP addresses of the sender domain's mail servers are on the Spamhaus black list. @@ -36006,7 +36087,7 @@ The latter can be disabled by turning off the &%outgoing_interface%& option. &%proxy%&: The internal (closest to the system running Exim) IP address of the proxy, tagged by PRX=, on the &"<="& line for a message accepted on a proxied connection -or the &"=>"& line for a message delivered on a proxied connection.. +or the &"=>"& line for a message delivered on a proxied connection. See &<>& for more information. .next .cindex "log" "incoming remote port" @@ -36037,7 +36118,7 @@ off the &%outgoing_interface%& option. .next .cindex "log" "outgoing remote port" .cindex "port" "logging outgoint remote" -.cindex "TCP/IP" "logging ougtoing remote port" +.cindex "TCP/IP" "logging outgoing remote port" &%outgoing_port%&: The remote port number is added to delivery log lines (those containing => tags) following the IP address. The local port is also added if &%incoming_interface%& and @@ -37866,9 +37947,8 @@ lock will be lost at the instant of rename. .next .vindex "&$body_linecount$&" If you change the number of lines in the file, the value of -&$body_linecount$&, which is stored in the -H file, will be incorrect. At -present, this value is not used by Exim, but there is no guarantee that this -will always be the case. +&$body_linecount$&, which is stored in the -H file, will be incorrect and can +cause incomplete transmission of messages or undeliverable messages. .next If the message is in MIME format, you must take care not to break it. .next @@ -38481,9 +38561,9 @@ To include this support, include &"SUPPORT_PROXY=yes"& in Local/Makefile. It was built on specifications from: -http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt +(&url(http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt)). That URL was revised in May 2014 to version 2 spec: -http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e +(&url(http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e)). The purpose of this facility is so that an application load balancer, such as HAProxy, can sit in front of several Exim servers @@ -38497,6 +38577,13 @@ recorded in an ACL (example is below). Use of a proxy is enabled by setting the &%hosts_proxy%& main configuration option to a hostlist; connections from these hosts will use Proxy Protocol. +Exim supports both version 1 and version 2 of the Proxy Protocol and +automatically determines which version is in use. + +The Proxy Protocol header is the first data received on a TCP connection +and is inserted before any TLS-on-connect handshake from the client; Exim +negotiates TLS between Exim-as-server and the remote client, not between +Exim and the proxy server. The following expansion variables are usable (&"internal"& and &"external"& here refer to the interfaces @@ -38617,6 +38704,12 @@ Exim has support for Internationalised mail names. To include this it must be built with SUPPORT_I18N and the libidn library. Standards supported are RFCs 2060, 5890, 6530 and 6533. +.new +If Exim is built with SUPPORT_I18N_2008 (in addition to SUPPORT_I18N, not +instead of it) then IDNA2008 is supported; this adds an extra library +requirement, upon libidn2. +.wen + .section "MTA operations" SECTi18nMTA .cindex SMTPUTF8 "ESMTP option" The main configuration option &%smtputf8_advertise_hosts%& specifies @@ -38789,7 +38882,7 @@ can be used to affect that action (more on this below). An additional variable, &$event_data$&, is filled with information varying with the event type: .display -&`msg:delivery `& smtp confirmation mssage +&`msg:delivery `& smtp confirmation message &`msg:rcpt:host:defer `& error string &`msg:rcpt:defer `& error string &`msg:host:defer `& error string