X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/049782c0de52a217f78116f82b3a1d69c0667458..aa3c7e485be428d9d436f917793c8598bfebd3a1:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 0632ba26b..e11881cb9 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -2766,6 +2766,8 @@ used to specify a path on the command line if a pid file is required. The SIGHUP signal .cindex "SIGHUP" .cindex "daemon" "restarting" +.cindex signal "to reload configuration" +.cindex daemon "reload configuration" can be used to cause the daemon to re-execute itself. This should be done whenever Exim's configuration file, or any file that is incorporated into it by means of the &%.include%& facility, is changed, and also whenever a new version @@ -6741,6 +6743,12 @@ lookup types support only literal keys. &*Warning 2*&: In a host list, you must always use &(net-iplsearch)& so that the implicit key is the host's IP address rather than its name (see section &<>&). + +.new +&*Warning 3*&: Do not use an IPv4-mapped IPv6 address for a key; use the +IPv4, in dotted-quad form. (Exim converts IPv4-mapped IPv6 addresses to this +notation before executing the lookup.) +.wen .next .new .cindex lookup json @@ -8678,8 +8686,12 @@ to quote keys was made available in &(lsearch)& files. However, the more recently implemented &(iplsearch)& files do require colons in IPv6 keys (notated using the quoting facility) so as to distinguish them from IPv4 keys. For this reason, when the lookup type is &(iplsearch)&, IPv6 addresses are -converted using colons and not dots. In all cases, full, unabbreviated IPv6 +converted using colons and not dots. +.new +In all cases except IPv4-mapped IPv6, full, unabbreviated IPv6 addresses are always used. +The latter are converted to IPv4 addresses, in dotted-quad form. +.wen Ideally, it would be nice to tidy up this anomalous situation by changing to colons in all cases, given that quoting is now available for &(lsearch)&. @@ -9188,6 +9200,7 @@ Many strings in Exim's runtime configuration are expanded before use. Some of them are expanded every time they are used; others are expanded only once. When a string is being expanded it is copied verbatim from left to right except +.cindex expansion "string concatenation" when a dollar or backslash character is encountered. A dollar specifies the start of a portion of the string that is interpreted and replaced as described below in section &<>& onwards. Backslash is used as an @@ -10944,11 +10957,15 @@ If the string is a single variable of type certificate, returns the SHA-1 hash fingerprint of the certificate. -.vitem &*${sha256:*&<&'string'&>&*}*& +.vitem &*${sha256:*&<&'string'&>&*}*& &&& + &*${sha2:*&<&'string'&>&*}*& &&& + &*${sha2_:*&<&'string'&>&*}*& .cindex "SHA-256 hash" +.cindex "SHA-2 hash" .cindex certificate fingerprint .cindex "expansion" "SHA-256 hashing" .cindex "&%sha256%& expansion item" +.cindex "&%sha2%& expansion item" The &%sha256%& operator computes the SHA-256 hash value of the string and returns it as a 64-digit hexadecimal number, in which any letters are in upper case. @@ -10956,6 +10973,15 @@ it as a 64-digit hexadecimal number, in which any letters are in upper case. If the string is a single variable of type certificate, returns the SHA-256 hash fingerprint of the certificate. +.new +The operator can also be spelled &%sha2%& and does the same as &%sha256%& +(except for certificates, which are not supported). +Finally, if an underbar +and a number is appended it specifies the output length, selecting a +member of the SHA-2 family of hash functions. +Values of 256, 384 and 512 are accepted, with 256 being the default. +.wen + .vitem &*${sha3:*&<&'string'&>&*}*& &&& &*${sha3_:*&<&'string'&>&*}*& @@ -12170,6 +12196,7 @@ This variable contains the version string of the Exim build. The first character is a major version number, currently 4. Then after a dot, the next group of digits is a minor version number. There may be other characters following the minor version. +This value may be overridden by the &%exim_version%& main config option. .vitem &$header_$&<&'name'&> This is not strictly an expansion variable. It is expansion syntax for @@ -13501,7 +13528,8 @@ Otherwise, empty. .vitem &$version_number$& .vindex "&$version_number$&" -The version number of Exim. +The version number of Exim. Same as &$exim_version$&, may be overridden +by the &%exim_version%& main config option. .vitem &$warn_message_delay$& .vindex "&$warn_message_delay$&" @@ -14340,6 +14368,7 @@ See also the &'Policy controls'& section above. .row &%ignore_fromline_hosts%& "allow &""From ""& from these hosts" .row &%ignore_fromline_local%& "allow &""From ""& from local SMTP" .row &%pipelining_advertise_hosts%& "advertise pipelining to these hosts" +.row &%pipelining_connect_advertise_hosts%& "advertise pipelining to these hosts" .row &%prdr_enable%& "advertise PRDR to all hosts" .row &%smtputf8_advertise_hosts%& "advertise SMTPUTF8 to these hosts" .row &%tls_advertise_hosts%& "advertise TLS to these hosts" @@ -15332,6 +15361,14 @@ not also supplied, the gid is taken from the result of &[getpwnam()]& if it is used. See chapter &<>& for a discussion of security issues. +.option exim_version main string "current version" +.cindex "Exim version" +.cindex customizing "version number" +.cindex "version number of Exim" override +This option allows to override the &$version_number$&/&$exim_version$& Exim reports in +various places. Use with care, this may fool stupid security scanners. + + .option extra_local_interfaces main "string list" unset This option defines network interfaces that are to be considered local when routing, but which are not used for listening by the daemon. See section @@ -16157,7 +16194,7 @@ 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 +no_ticket" +.option openssl_options main "string list" "+no_sslv2 +no_sslv3 +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, @@ -16337,6 +16374,19 @@ for each SMTP command and response. When PIPELINING is advertised, Exim assumes that clients will use it; &"out of order"& commands that are &"expected"& do not count as protocol errors (see &%smtp_max_synprot_errors%&). +.new +.option pipelining_connect_advertise_hosts main "host list&!!" * +.cindex "pipelining" "early connection" +.cindex "pipelining" PIPE_CONNECT +If Exim is built with the SUPPORT_PIPE_CONNECT build option +this option controls which hosts the facility is advertised to +and from which pipeline early-connection (before MAIL) SMTP +commands are acceptable. +When used, the pipelining saves on roundtrip times. + +Currently the option name &"X_PIPE_CONNECT"& is used. +.wen + .option prdr_enable main boolean false .cindex "PRDR" "enabling on server" @@ -17553,7 +17603,7 @@ use when sending messages as a client, you must set the &%tls_certificate%& option in the relevant &(smtp)& transport. &*Note*&: If you use filenames based on IP addresses, change the list -separator in the usual way (&<>&) >to avoid confusion under IPv6. +separator in the usual way (&<>&) to avoid confusion under IPv6. &*Note*&: Under versions of OpenSSL preceding 1.1.1, when a list of more than one @@ -23646,7 +23696,7 @@ inserted in the argument list at that point &'as a separate argument'&. This avoids any problems with spaces or shell metacharacters, and is of use when a &(pipe)& transport is handling groups of addresses in a batch. -If &%force_command%& is enabled on the transport, Special handling takes place +If &%force_command%& is enabled on the transport, special handling takes place for an argument that consists of precisely the text &`$address_pipe`&. It is handled similarly to &$pipe_addresses$& above. It is expanded and each argument is inserted in the argument list at that point @@ -24517,6 +24567,30 @@ facilities such as AUTH, PIPELINING, SIZE, and STARTTLS. Exim will not use the SMTP PIPELINING extension when delivering to any host that matches this list, even if the server host advertises PIPELINING support. +.new +.option hosts_pipe_connect smtp "host list&!!" unset +.cindex "pipelining" "early connection" +.cindex "pipelining" PIPE_CONNECT +If Exim is built with the SUPPORT_PIPE_CONNECT build option +this option controls which to hosts the facility watched for +and recorded, and used for subsequent connections. + +The retry hints database is used for the record, +and records are subject to the &%retry_data_expire%& option. +When used, the pipelining saves on roundtrip times. +It also turns SMTP into a client-first protocol +so combines well with TCP Fast Open. + +Note: +When the facility is used, the transport &%helo_data%& option +will be expanded before the &$sending_ip_address$& variable +is filled in. +A check is made for the use of that variable, without the +presence of a &"def:"& test on it, but suitably complex coding +can avoid the check and produce unexpected results. +You have been warned. +.wen + .option hosts_avoid_tls smtp "host list&!!" unset .cindex "TLS" "avoiding for certain hosts" @@ -24556,13 +24630,15 @@ been started will not be passed to a new delivery process for sending another message on the same connection. See section &<>& for an explanation of when this might be needed. -.option hosts_noproxy_tls smtp "host list&!!" * +.new +.option hosts_noproxy_tls smtp "host list&!!" unset .cindex "TLS" "passing connection" .cindex "multiple SMTP deliveries" .cindex "TLS" "multiple message deliveries" For any host that matches this list, a TLS session which has been started will not be passed to a new delivery process for sending another message on the same session. +.wen The traditional implementation closes down TLS and re-starts it in the new process, on the same open TCP connection, for each successive message @@ -24658,7 +24734,7 @@ 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 conjunction with a transport filter. -.option hosts_try_dane smtp "host list&!!" unset +.option hosts_try_dane smtp "host list&!!" * .cindex DANE "transport options" .cindex DANE "attempting for certain servers" If built with DANE support, Exim will lookup a @@ -24668,7 +24744,7 @@ a DANE-verified TLS connection is made to that host; there will be no fallback to in-clear communication. See section &<>&. -.option hosts_try_fastopen smtp "host list&!!" unset +.option hosts_try_fastopen smtp "host list&!!" * .cindex "fast open, TCP" "enabling, in client" .cindex "TCP Fast Open" "enabling, in client" .cindex "RFC 7413" "TCP Fast Open" @@ -28307,7 +28383,7 @@ There is no current way to staple a proof for a client certificate. -.section "Configuring an Exim client to use TLS" "SECID185" +.section "Configuring an Exim client to use TLS" "SECTclientTLS" .cindex "cipher" "logging" .cindex "log" "TLS cipher" .cindex "log" "distinguished name" @@ -30826,13 +30902,13 @@ client host, and its contents have been verified. If there has been no previous attempt to verify the HELO/EHLO contents, it is carried out when this condition is encountered. See the description of the &%helo_verify_hosts%& and &%helo_try_verify_hosts%& options for details of how to request verification -independently of this condition. +independently of this condition, and for detail of the verification. For SMTP input that does not come over TCP/IP (the &%-bs%& command line option), this condition is always true. -.vitem &*verify&~=&~not_blind*& +.vitem &*verify&~=&~not_blind/*&<&'options'&> .cindex "verifying" "not blind" .cindex "bcc recipients, verifying none" This condition checks that there are no blind (bcc) recipients in the message. @@ -30842,6 +30918,11 @@ case-sensitively; domains are checked case-insensitively. If &'Resent-To:'& or &'Resent-Cc:'& header lines exist, they are also checked. This condition can be used only in a DATA or non-SMTP ACL. +.new +There is one possible option, &`case_insensitive`&. If this is present then +local parts are checked case-insensitively. +.wen + There are, of course, many legitimate messages that make use of blind (bcc) recipients. This check should not be used on its own for blocking messages. @@ -37337,6 +37418,15 @@ The field is a single "L". On accept lines, where PIPELINING was offered but not used by the client, the field has a minus appended. + +.new +.cindex "pipelining" "early connection" +If Exim is built with the SUPPORT_PIPE_CONNECT build option +accept "L" fields have a period appended if the feature was +offered but not used, or an asterisk appended if used. +Delivery "L" fields have an asterisk appended if used. +.wen + .next .cindex "log" "queue run" .cindex "queue runner" "logging" @@ -37692,6 +37782,11 @@ Match only frozen messages. .vitem &*-x*& Match only non-frozen messages. + +.new +.vitem &*-G*&&~<&'queuename'&> +Match only messages in the given queue. Without this, the default queue is searched. +.wen .endlist The following options control the format of the output: @@ -39624,8 +39719,9 @@ Signers MUST use RSA keys of at least 1024 bits for all keys. Signers SHOULD use RSA keys of at least 2048 bits. .endd -Support for EC keys is being developed under -&url(https://datatracker.ietf.org/doc/draft-ietf-dcrup-dkim-crypto/). +.new +EC keys for DKIM are defined by RFC 8463. +.wen They are considerably smaller than RSA keys for equivalent protection. As they are a recent development, users should consider dual-signing (by setting a list of selectors, and an expansion for this option) @@ -39645,10 +39741,12 @@ openssl pkey -outform DER -pubout -in dkim_ed25519.private | tail -c +13 | base6 certtool --load_privkey=dkim_ed25519.private --pubkey_info --outder | tail -c +13 | base64 .endd -Note that the format -of Ed25519 keys in DNS has not yet been decided; this release supports -both of the leading candidates at this time, a future release will -probably drop support for whichever proposal loses. +.new +Exim also supports an alternate format +of Ed25519 keys in DNS which was a candidate during development +of the standard, but not adopted. +A future release will probably drop that support. +.wen .option dkim_hash smtp string&!! sha256 Can be set to any one of the supported hash methods, which are: