X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/107077d7fd6736711bf5cd980221723401d37c51..37b849dca4dfd855212a763662825e:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 7db80b2ae..5a757c4ed 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -46,7 +46,7 @@ . Update the Copyright year (only) when changing content. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.96" +.set previousversion "4.97" .include ./local_params .set ACL "access control lists (ACLs)" @@ -996,12 +996,9 @@ contains the number of seconds since the start of the epoch (the normal Unix way of representing the date and time of day). .next After the first hyphen, the next -.new eleven -.wen characters are the id of the process that received the message. .next -.new There are two different possibilities for the final four characters: .olist .oindex "&%localhost_number%&" @@ -1017,7 +1014,6 @@ If &%localhost_number%& is set, it is multiplied by 500000 (250000) and added to the fractional part of the time, which in this case is in units of 2 us (4 us). .endlist -.wen .endlist After a message has been received, Exim waits for the clock to tick at the @@ -2846,13 +2842,11 @@ of Exim is installed. It is not necessary to do this when other files that are referenced from the configuration (for example, alias files) are changed, because these are reread each time they are used. -.new Either a SIGTERM or a SIGINT signal should be used to cause the daemon to cleanly shut down. Subprocesses handling recceiving or delivering messages, or for scanning the queue, will not be affected by the termination of the daemon process. -.wen .cmdopt -bdf This option has the same effect as &%-bd%& except that it never disconnects @@ -2890,11 +2884,9 @@ defined and macros will be expanded. Because macros in the config file are often used for secrets, those are only available to admin users. -.new The word &"set"& at the start of a line, followed by a single space, is recognised specially as defining a value for a variable. The syntax is otherwise the same as the ACL modifier &"set ="&. -.wen .cmdopt -bem <&'filename'&> .cindex "testing" "string expansion" @@ -4450,7 +4442,6 @@ It is only relevant when the &%-bd%& (start listening daemon) option is also given. Normally the daemon creates this socket, unless a &%-oX%& and &*no*& &%-oP%& option is also present. -.new If this option is given then the socket will not be created. This is required if the system is running multiple daemons, in which case it should be used on all. @@ -4464,7 +4455,6 @@ caching compiled regexes .next obtaining a current queue size .endlist -.wen .cmdopt -pd .cindex "Perl" "starting the interpreter" @@ -4569,12 +4559,10 @@ delivered down a single SMTP .cindex "multiple SMTP deliveries" connection because of the hints that were set up during the first queue scan. -.new Two-phase queue runs should be used on systems which, even intermittently, have a large queue (such as mailing-list operators). They may also be useful for hosts that are connected to the Internet intermittently. -.wen .vitem &%-q[q]i...%& .oindex "&%-qi%&" @@ -4660,14 +4648,12 @@ combined daemon at system boot time is to use a command such as Such a daemon listens for incoming SMTP calls, and also starts a queue runner process every 30 minutes. -.new .cindex "named queues" "queue runners" It is possible to set up runners for multiple named queues within one daemon, For example: .code exim -qGhipri/2m -q10m -qqGmailinglist/1h .endd -.wen When a daemon is started by &%-q%& with a time value, but without &%-bd%&, no pid file is written unless one is explicitly requested by the &%-oP%& option. @@ -7409,10 +7395,8 @@ For example, the way to write the NIS+ query is [name="${quote_nisplus:$local_part}"] .endd .cindex "tainted data" "in lookups" -.new &*All*& tainted data used in a query-style lookup must be quoted using a mechanism appropriate for the lookup type. -.wen See chapter &<>& for full coverage of string expansions. The quote operator can be used for all lookup types, but has no effect for single-key lookups, since no quoting is ever needed in their key strings. @@ -9622,7 +9606,6 @@ value. Nevertheless the &%-be%& option can be useful for checking out file and database lookups, and the use of expansion operators such as &%sg%&, &%substr%& and &%nhash%&. -.new When reading lines from the standard input, macros can be defined and ACL variables can be set. For example: @@ -9631,7 +9614,6 @@ MY_MACRO = foo set acl_m_myvar = bar .endd Such macros and variables can then be used in later input lines. -.wen Exim gives up its root privilege when it is called with the &%-be%& option, and instead runs under the uid and gid it was called with, to prevent users from @@ -9748,9 +9730,7 @@ Example use (as an ACL modifier): add_header = :at_start:${authresults {$primary_hostname}} .endd This is safe even if no authentication results are available -.new and would generally be placed in the DATA ACL. -.wen .vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&& @@ -10010,9 +9990,7 @@ default, but the separator can be changed in the usual way (&<&*_*&<&'limit'&>&*:*&<&'string'&>&*}*& .cindex header "wrapping operator" .cindex expansion "header wrapping" @@ -11136,7 +11113,6 @@ column number is reached. Whitespace at a chosen wrap point is removed. A line-wrap consists of a newline followed by a tab, and the tab is counted as 8 columns. -.wen @@ -13436,7 +13412,6 @@ The main use of this variable is expected to be to distinguish between rejections of MAIL and rejections of RCPT. .tvar &$recipients$& -.new .tvar &$recipients_list$& These variables both contain the envelope recipients for a message. @@ -13445,7 +13420,6 @@ The first uses a comma and a space separate the addresses in the replacement tex this variable is not intended for further processing. The second is a proper Exim list; colon-separated. -.wen However, the variables are not generally available, to prevent exposure of Bcc recipients in @@ -15754,10 +15728,8 @@ by a setting such as this: dns_again_means_nonexist = *.in-addr.arpa .endd This option applies to all DNS lookups that Exim does, -.new except for TLSA lookups (where knowing about such failures is security-relevant). -.wen It also applies when the &[gethostbyname()]& or &[getipnodebyname()]& functions give temporary errors, since these are most likely to be caused by DNS lookup problems. The @@ -16337,10 +16309,8 @@ This option is obsolete, and retained only for backward compatibility, because nowadays the ACL specified by &%acl_smtp_connect%& can also reject incoming connections immediately. -.new If the connection is on a TLS-on-connect port then the TCP connection is just dropped. Otherwise, an SMTP error is sent first. -.wen The ability to give an immediate rejection (either by this option or using an ACL) is provided for use in unusual cases. Many hosts will just try again, @@ -16361,10 +16331,8 @@ local processes, you must create a host list with an empty item. For example: .code hosts_connection_nolog = : .endd -.new The hosts affected by this option also do not log "no MAIL in SMTP connection" lines, as may commonly be produced by a monitoring system. -.wen .option hosts_require_alpn main "host list&!!" unset @@ -17036,7 +17004,6 @@ to be used in conjunction with &(oracle)& lookups (see section &<>&). The option is available only if Exim has been built with Oracle support. -.new .option panic_coredump main boolean false This option is rarely needed but can help for some debugging investigations. If set, when an internal error is detected by Exim which is sufficient @@ -17047,7 +17014,6 @@ then a coredump is requested. Note that most systems require additional administrative configuration to permit write a core file for a setuid program, which is Exim's common installed configuration. -.wen .option percent_hack_domains main "domain list&!!" unset .cindex "&""percent hack""&" @@ -17830,10 +17796,8 @@ positive response to an SMTP connection. The default setting is: smtp_banner = $smtp_active_hostname ESMTP Exim \ $version_number $tod_full .endd -.new Failure to expand the string causes a panic error; a forced fail just closes the connection. -.wen If you want to create a multiline response to the initial SMTP connection, use &"\n"& in the string at appropriate points, but not at the end. Note that the 220 code is not included @@ -18579,9 +18543,7 @@ It has no effect when Exim is used with GnuTLS &%tls_require_ciphers%& option). After expansion it must contain -.new one or (only for OpenSSL versiona 1.1.1 onwards) more -.wen EC curve names, such as &`prime256v1`&, &`secp384r1`&, or &`P-521`&. Consult your OpenSSL manual for valid curve names. @@ -18589,9 +18551,7 @@ 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. -.new If the option expands to an empty string, the effect is undefined. -.wen .option tls_ocsp_file main string&!! unset @@ -22832,8 +22792,11 @@ If unset, or expanding to an empty string, no filtering is done. When the message is about to be written out, the command specified by &%transport_filter%& is started up in a separate, parallel process, and the entire message, including the header lines, is passed to it on its standard -input (this in fact is done from a third process, to avoid deadlock). The -command must be specified as an absolute path. +input (this in fact is done from a third process, to avoid deadlock). +The command must be specified as an absolute path. + +The process run by the command must use its standard input as the message +data to be transformed, and write the results on its standard output. The lines of the message that are written to the transport filter are terminated by newline (&"\n"&). The message is passed to the filter before any @@ -25783,11 +25746,9 @@ Exim will request a Certificate Status on a TLS session for any host that matches this list. &%tls_verify_certificates%& should also be set for the transport. -.new The default is &"**"& if DANE is not in use for the connection, or if DANE-TA us used. It is empty if DANE-EE is used. -.wen .option hosts_require_alpn smtp "host list&!!" unset .cindex ALPN "require negotiation in client" @@ -25933,16 +25894,12 @@ has advertised support for IGNOREQUOTA in its response to the LHLO command. .option max_rcpt smtp integer&!! 100 .cindex "RCPT" "maximum number of outgoing" This option, -.new after expansion, -.wen limits the number of RCPT commands that are sent in a single SMTP message transaction. A value setting of zero disables the limit. -.new If a constant is given, -.wen each set of addresses is treated independently, and so can cause parallel connections to the same host if &%remote_max_parallel%& permits this. @@ -27753,7 +27710,6 @@ no successful authentication. Successful authentication sets up information used by the &%authresults%& expansion item. -.new .cindex authentication "failure event, server" If an authenticator is run and does not succeed, an event (see &<>&) of type "auth:fail" is raised. @@ -27764,7 +27720,6 @@ will be valid. If the event is serviced and a string is returned then the string will be logged instead of the default log line. See <> for details on events. -.wen .section "Testing server authentication" "SECID169" @@ -27843,7 +27798,6 @@ Exim abandons trying to send the message to the host for the moment. It will try again later. If there are any backup hosts available, they are tried in the usual way. -.new .next .cindex authentication "failure event, client" If the response to authentication is a permanent error (5&'xx'& code), @@ -27853,7 +27807,6 @@ While the event is being processed the variable will be valid. If the event is serviced and a string is returned then the string will be logged. See <> for details on events. -.wen .next If the response to authentication is a permanent error (5&'xx'& code), Exim @@ -28433,11 +28386,9 @@ dovecot_ntlm: server_set_id = $auth1 .endd -.new &*Note*&: plaintext authentication methods such as PLAIN and LOGIN should not be advertised on cleartext SMTP connections. See the discussion in section &<>&. -.wen If the SMTP connection is encrypted, or if &$sender_host_address$& is equal to &$received_ip_address$& (that is, the connection is local), the &"secured"& @@ -30670,11 +30621,9 @@ accepted by an &%accept%& verb that has a &%message%& modifier, the contents of the message override the banner message that is otherwise specified by the &%smtp_banner%& option. -.new For tls-on-connect connections, the ACL is run before the TLS connection is accepted; if the ACL does not accept then the TCP connection is dropped without any TLS startup attempt and without any SMTP response being transmitted. -.wen .subsection "The EHLO/HELO ACL" SECID192 @@ -32211,7 +32160,6 @@ DATA, MIME or DKIM ACLs for a message delivered by cutthrough routing. More than one header can be removed at the same time by using a colon separated list of header specifiers. -.new If a specifier does not start with a circumflex (^) then it is treated as a header name. The header name matching is case insensitive. @@ -32225,7 +32173,6 @@ Example: .code remove_header = \N^(?i)Authentication-Results\s*::\s*example.org;\N .endd -.wen List expansion is not performed, so you cannot use hostlists to create a list of headers, however both connection and message variable expansion @@ -39187,12 +39134,10 @@ only way to log such cases is to interpose a script such as &_util/logargs.sh_& between the caller and Exim. .next .cindex "log" "connection identifier" -.new &%connection_identifier%&: An identifier for the accepted connection is added to connection start and end lines and to message accept lines. The identifier is tagged by Ci=. The value is PID-based, so will reset on reboot and will wrap. -.wen .next .cindex "log" "connection rejections" &%connection_reject%&: A log entry is written whenever an incoming SMTP @@ -41791,8 +41736,9 @@ RFC 6376 lists these tags as RECOMMENDED. Verification of DKIM signatures in SMTP incoming email is done for all messages for which an ACL control &%dkim_disable_verify%& has not been set. + .cindex DKIM "selecting signature algorithms" -Individual classes of signature algorithm can be ignored by changing +Individual classes of DKIM signature algorithm can be ignored by changing the main options &%dkim_verify_hashes%& or &%dkim_verify_keytypes%&. The &%dkim_verify_minimal%& option can be set to cease verification processing for a message once the first passing signature is found. @@ -41805,7 +41751,7 @@ For most purposes the default option settings suffice and the remainder of this section can be ignored. The results of verification are made available to the -&%acl_smtp_dkim%& ACL, which can examine and modify them. +&%acl_smtp_dkim%& ACL, which (for complex needs) can examine and modify them. A missing ACL definition defaults to accept. By default, the ACL is called once for each syntactically(!) correct signature in the incoming message. @@ -41870,6 +41816,12 @@ an identity. This is one of the list items from the expanded main option &%dkim_verify_signers%& (see above). .vitem &%$dkim_verify_status%& +So long as a DKIM ACL is defined +(it need do no more than accept, which is the default), +after all the DKIM ACL runs have completed, the value becomes a +colon-separated list of the values after each run. +The value is maintained for the MIME, PRDR and DATA ACLs. + Within the DKIM ACL, a string describing the general status of the signature. One of .ilist @@ -41898,11 +41850,6 @@ hash-method or key-size: set dkim_verify_reason = hash too weak or key too short .endd -So long as a DKIM ACL is defined (it need do no more than accept), -after all the DKIM ACL runs have completed, the value becomes a -colon-separated list of the values after each run. -This is maintained for the mime, prdr and data ACLs. - .vitem &%$dkim_verify_reason%& A string giving a little bit more detail when &%$dkim_verify_status%& is either "fail" or "invalid". One of @@ -42027,13 +41974,15 @@ option. .endlist -In addition, two ACL conditions are provided, usable only in a DKIM ACL: +In addition, two ACL conditions are provided: .vlist .vitem &%dkim_signers%& 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 &%$dkim_cur_signer%&). This is typically used to restrict an ACL +(reflected by &%$dkim_cur_signer%&). +This condition is only usable in a DKIM ACL. +This is typically used to restrict an ACL verb to a group of domains or identities. For example: .code @@ -42049,7 +41998,18 @@ for that check for empty &$h_DKIM-Signature:$& in the data ACL. .vitem &%dkim_status%& ACL condition that checks a colon-separated list of possible DKIM verification -results against the actual result of verification. This is typically used +results against the actual result of verification, +given by &$dkim_verify_status$& if that is non-empty or "none" if empty. +.new +This condition may be used in DKIM, MIME, PRDR and DATA ACLs. +.wen + +A basic verification might be: +.code +deny !dkim_status = pass:none:invalid +.endd + +A more complex use could be to restrict an ACL verb to a list of verification outcomes, for example: .code @@ -42062,6 +42022,12 @@ deny sender_domains = paypal.com:paypal.de The possible status keywords are: 'none','invalid','fail' and 'pass'. Please see the documentation of the &%$dkim_verify_status%& expansion variable above for more information of what they mean. + +The condition is true if the status +.new +(or any of the list of status values) +.wen +is any one of the supplied list. .endlist @@ -42314,11 +42280,9 @@ return false. If it is, the condition will return true and the variable &$srs_recipient$& will be set to the decoded (original) value. -.new If the second argument is empty then the condition returns true if the first argument is in valid SRS formet, else false. The variable &$srs_recipient$& is not set for this case. -.wen .endlist Example usage: