X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/fb05276aaee4c27b6f20fb1f32290ee40a929064..9537fc00a962f7f15c66e3151ee5fcfc62cc6f3f:/doc/doc-docbook/spec.xfpt?ds=inline diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 478b5e1a4..da2a41a2e 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -52,7 +52,7 @@ .set I "    " .macro copyyear -2016 +2017 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -436,6 +436,7 @@ 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 @@ -4481,12 +4482,12 @@ 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 .wen @@ -4926,8 +4927,12 @@ 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. @@ -5043,11 +5048,17 @@ They can be used to conditionally include parts of a configuration The following classes of macros are defined: .display -&` _HAVE_ `& build-time defines -&` _DRVR_AUTH_ `& authehticator drivers -&` _DRVR_RTR_ `& router drivers -&` _DRVR_TPT_ `& transport drivers -&` _OPT_ `& configuration option support +&` _HAVE_* `& build-time defines +&` _DRIVER_ROUTER_* `& router drivers +&` _DRIVER_TRANSPORT_* `& transport drivers +&` _DRIVER_AUTHENTICATOR_* `& authenticator drivers +&` _OPT_MAIN_* `& main config options +&` _OPT_ROUTERS_* `& generic router options +&` _OPT_TRANSPORTS_* `& generic transport options +&` _OPT_AUTHENTICATORS_* `& generic authenticator options +&` _OPT_ROUTER_*_* `& private router options +&` _OPT_TRANSPORT_*_* `& private transport options +&` _OPT_AUTHENTICATOR_*_* `& private authenticator options .endd Use an &"exim -bP macros"& command to get the list of macros. @@ -7113,7 +7124,7 @@ 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). @@ -9110,7 +9121,7 @@ If the ACL returns defer the result is a forced-fail. Otherwise the expansion f .vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&& {*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&" -.cindex "expansion" "extracting cerificate fields" +.cindex "expansion" "extracting certificate fields" .cindex "&%certextract%&" "certificate fields" .cindex "certificate" "extracting fields" The <&'certificate'&> must be a variable of type certificate. @@ -9427,12 +9438,19 @@ message, and any that are added by an ACL statement or by a system filter. Header lines that are added to a particular copy of a message by a router or transport are not accessible. -For incoming SMTP messages, no header lines are visible in ACLs that are obeyed -before the DATA ACL, because the header structure is not set up until the -message is received. Header lines that are added in a RCPT ACL (for example) +For incoming SMTP messages, no header lines are visible in +.new +ACLs that are obeyed before the data phase completes, +.wen +because the header structure is not set up until the message is received. +They are visible in DKIM, PRDR and DATA ACLs. +Header lines that are added in a RCPT ACL (for example) are saved until the message's incoming header lines are available, at which -point they are added. When a DATA ACL is running, however, header lines added -by earlier ACLs are visible. +point they are added. +.new +When any of the above ACLs ar +.wen +running, however, header lines added by earlier ACLs are visible. Upper case and lower case letters are synonymous in header names. If the following character is white space, the terminating colon may be omitted, but @@ -12216,7 +12234,7 @@ normally the gid of the Exim user. .cindex "uid (user id)" "of originating user" .cindex "sender" "uid" .vindex "&$caller_uid$&" -.vindex "&$originaltor_uid$&" +.vindex "&$originator_uid$&" The value of &$caller_uid$& that was set when the message was received. For messages received via the command line, this is the uid of the sending user. For messages received by SMTP over TCP/IP, this is normally the uid of the Exim @@ -12617,6 +12635,13 @@ validating resolver (e.g. unbound, or bind with suitable configuration). If you have changed &%host_lookup_order%& so that &`bydns`& is not the first mechanism in the list, then this variable will be false. +.new +This requires that your system resolver library support EDNS0 (and that +DNSSEC flags exist in the system headers). If the resolver silently drops +all EDNS0 options, then this will have no effect. OpenBSD's asr resolver +is known to currently ignore EDNS0, documented in CAVEATS of asr_run(3). +.wen + .vitem &$sender_host_name$& .vindex "&$sender_host_name$&" @@ -12838,7 +12863,7 @@ If TLS has not been negotiated, the value will be 0. .vitem &$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 @@ -13109,7 +13134,7 @@ 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. @@ -13593,6 +13618,7 @@ listed in more than one group. .row &%slow_lookup_log%& "control logging of slow DNS lookups" .row &%syslog_duplication%& "controls duplicate log lines on syslog" .row &%syslog_facility%& "set syslog &""facility""& field" +.row &%syslog_pid%& "pid in syslog lines" .row &%syslog_processname%& "set syslog &""ident""& field" .row &%syslog_timestamp%& "timestamp syslog lines" .row &%write_rejectlog%& "control use of message log" @@ -14029,6 +14055,7 @@ 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. @@ -14425,7 +14452,7 @@ it obviously cannot send an error message of any kind. .new 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. .wen @@ -14687,6 +14714,7 @@ 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 @@ -14694,6 +14722,12 @@ 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 @@ -14792,7 +14826,7 @@ 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" @@ -15143,7 +15177,7 @@ 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 @@ -15317,6 +15351,9 @@ 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 @@ -16735,7 +16772,7 @@ 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. @@ -16856,6 +16893,15 @@ If this option is unset, &"mail"& is used. See chapter &<>& for details of Exim's logging. +.option syslog_pid main boolean true +.cindex "syslog" "pid" +If &%syslog_pid%& is set false, the PID on Exim's log lines are +omitted when these lines are sent to syslog. (Syslog normally prefixes +the log lines with the PID of the logging process automatically.) You need +to enable the &`+pid`& log selector item, if you want Exim to write it's PID +into the logs.) See chapter &<>& for details of Exim's logging. + + .option syslog_processname main string &`exim`& .cindex "syslog" "process name; setting" @@ -16883,6 +16929,9 @@ 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 @@ -17129,17 +17178,19 @@ prior to the 4.80 release, as Debian used to patch Exim to raise the minimum acceptable bound from 1024 to 2048. -.option tls_eccurve main string&!! prime256v1 +.option tls_eccurve main string&!! &`auto`& .cindex TLS "EC cryptography" -If built with a recent-enough version of OpenSSL, -this option selects a EC curve for use by Exim. +This option selects a EC curve for use by Exim. + +After expansion it must contain a valid EC curve parameter, such as +&`prime256v1`&, &`secp384r1`&, or &`P-512`&. Consult your OpenSSL manual +for valid selections. -Curve names of the form &'prime256v1'& are accepted. -For even more-recent library versions, names of the form &'P-512'& -are also accepted, plus the special value &'auto'& -which tells the library to choose. +For OpenSSL versions before (and not including) 1.0.2, the string +&`auto`& selects &`prime256v1`&. For more recent OpenSSL versions +&`auto`& tells the library to choose. -If the option is set to an empty string, no EC curves will be enabled. +If the option expands to an empty string, no EC curves will be enabled. .option tls_ocsp_file main string&!! unset @@ -20908,7 +20959,7 @@ 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" @@ -21023,7 +21074,7 @@ 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 @@ -23280,12 +23331,12 @@ message_suffix = &`\n`& to &`\r\n`& in &%message_suffix%&. -.option path pipe string "see below" -This option specifies the string that is set up in the PATH environment -variable of the subprocess. The default is: -.code -/bin:/usr/bin -.endd +.option path pipe string&!! "/bin:/usr/bin" +.new +This option is expanded and +.wen +specifies the string that is set up in the PATH environment +variable of the subprocess. If the &%command%& option does not yield an absolute path name, the command is sought in the PATH directories, in the usual way. &*Warning*&: This does not apply to a command specified as a transport filter. @@ -23670,7 +23721,7 @@ 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 @@ -23988,14 +24039,14 @@ 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. .wen .new .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. @@ -24180,7 +24231,7 @@ 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 @@ -25885,6 +25936,19 @@ 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 @@ -26794,7 +26858,7 @@ tls: .endd This accepts a client certificate that is verifiable against any of your configured trust-anchors -which usually means the full set of public CAs) +(which usually means the full set of public CAs) and which has a SAN with a good account name. Note that the client cert is on the wire in-clear, including the SAN, whereas a plaintext SMTP AUTH done inside TLS is not. @@ -27559,7 +27623,7 @@ 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$& is arbitrary unverified data provided prior to authentication. .new -Further, the initial cerificate is loaded before SNI is arrived, so +Further, the initial certificate is loaded before SNI is arrived, so an expansion for &%tls_certificate%& must have a default which is used when &$tls_in_sni$& is empty. .wen @@ -28106,6 +28170,11 @@ 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 @@ -28927,7 +28996,11 @@ 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. @@ -28942,7 +29015,7 @@ 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. .wen Delivery in this mode avoids the generation of a bounce mail to a @@ -29169,7 +29242,7 @@ 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 @@ -29782,6 +29855,15 @@ 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 @@ -29841,7 +29923,7 @@ 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), @@ -29954,7 +30036,7 @@ 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. @@ -31658,6 +31740,15 @@ configuration as follows (example): .code spamd_address = 192.168.99.45 387 .endd +The SpamAssassin protocol relies on a TCP half-close from the client. +If your SpamAssassin client side is running a Linux system with an +iptables firewall, consider setting +&%net.netfilter.nf_conntrack_tcp_timeout_close_wait%& to at least the +timeout, Exim uses when waiting for a response from the SpamAssassin +server (currently defaulting to 120s). With a lower value the Linux +connection tracking may consider your half-closed connection as dead too +soon. + To use Rspamd (which by default listens on all local addresses on TCP port 11333) @@ -36071,7 +36162,7 @@ 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 @@ -37900,9 +37991,8 @@ 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 @@ -38246,6 +38336,7 @@ These options take (expandable) strings as arguments. MANDATORY: The domain you want to sign with. The result of this expanded option is put into the &%$dkim_domain%& expansion variable. +If it is empty after expansion, DKIM signing is not done. .option dkim_selector smtp string&!! unset MANDATORY: @@ -38518,9 +38609,9 @@ To include this support, include &"SUPPORT_PROXY=yes"& in Local/Makefile. It was built on specifications from: -http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt +(&url(http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt)). That URL was revised in May 2014 to version 2 spec: -http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e +(&url(http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e)). The purpose of this facility is so that an application load balancer, such as HAProxy, can sit in front of several Exim servers @@ -38769,7 +38860,7 @@ must be representable in UTF-16. .cindex events The events mechanism in Exim can be used to intercept processing at a number -of points. It was originally invented to giave a way to do customised logging +of points. It was originally invented to give a way to do customised logging actions (for example, to a database) but can also be used to modify some processing actions. @@ -38828,7 +38919,7 @@ can be used to affect that action (more on this below). An additional variable, &$event_data$&, is filled with information varying with the event type: .display -&`msg:delivery `& smtp confirmation mssage +&`msg:delivery `& smtp confirmation message &`msg:rcpt:host:defer `& error string &`msg:rcpt:defer `& error string &`msg:host:defer `& error string @@ -38839,7 +38930,7 @@ with the event type: The :defer events populate one extra variable: &$event_defer_errno$&. For complex operations an ACL expansion can be used in &%event_action%& -however due to the multiple contextx that Exim operates in during +however due to the multiple contexts that Exim operates in during the course of its processing: .ilist variables set in transport events will not be visible outside that