X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/1a2e76e1676bf405a464a233950a95012533c227..b2d54f831659ee95d4d4cf395f568b395e262310:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index c2adc9ea6..294034a6c 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -52,7 +52,7 @@ .set I "    " .macro copyyear -2018 +2018, 2019 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -1886,11 +1886,10 @@ to your &_Local/Makefile_& and rebuild Exim. .section "Including TLS/SSL encryption support" "SECTinctlsssl" .cindex "TLS" "including support for TLS" .cindex "encryption" "including support for" -.cindex "SUPPORT_TLS" .cindex "OpenSSL" "building Exim with" .cindex "GnuTLS" "building Exim with" -Exim can be built to support encrypted SMTP connections, using the STARTTLS -command as per RFC 2487. It can also support legacy clients that expect to +Exim is usually built to support encrypted SMTP connections, using the STARTTLS +command as per RFC 2487. It can also support clients that expect to start a TLS session immediately on connection to a non-standard port (see the &%tls_on_connect_ports%& runtime option and the &%-tls-on-connect%& command line option). @@ -1899,35 +1898,41 @@ If you want to build Exim with TLS support, you must first install either the OpenSSL or GnuTLS library. There is no cryptographic code in Exim itself for implementing SSL. +.new +If you do not want TLS support you should set +.code +DISABLE_TLS=yes +.endd +in &_Local/Makefile_&. +.wen + If OpenSSL is installed, you should set .code -SUPPORT_TLS=yes +USE_OPENSL=yes TLS_LIBS=-lssl -lcrypto .endd in &_Local/Makefile_&. You may also need to specify the locations of the OpenSSL library and include files. For example: .code -SUPPORT_TLS=yes +USE_OPENSL=yes TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto TLS_INCLUDE=-I/usr/local/openssl/include/ .endd .cindex "pkg-config" "OpenSSL" If you have &'pkg-config'& available, then instead you can just use: .code -SUPPORT_TLS=yes +USE_OPENSL=yes USE_OPENSSL_PC=openssl .endd .cindex "USE_GNUTLS" If GnuTLS is installed, you should set .code -SUPPORT_TLS=yes USE_GNUTLS=yes TLS_LIBS=-lgnutls -ltasn1 -lgcrypt .endd in &_Local/Makefile_&, and again you may need to specify the locations of the library and include files. For example: .code -SUPPORT_TLS=yes USE_GNUTLS=yes TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt TLS_INCLUDE=-I/usr/gnu/include @@ -1935,7 +1940,6 @@ TLS_INCLUDE=-I/usr/gnu/include .cindex "pkg-config" "GnuTLS" If you have &'pkg-config'& available, then instead you can just use: .code -SUPPORT_TLS=yes USE_GNUTLS=yes USE_GNUTLS_PC=gnutls .endd @@ -3959,6 +3963,20 @@ is sent to the sender, containing the text &"cancelled by administrator"&. Bounce messages are just discarded. This option can be used only by an admin user. +.new +.vitem &%-MG%&&~<&'queue&~name'&&~<&'message&~id'&>&~<&'message&~id'&>&~... +.oindex "&%-MG%&" +.cindex queue named +.cindex "named queues" +.cindex "queue" "moving messages" +This option requests that each listed message be moved from its current +queue to the given named queue. +The destination queue name argument is required, but can be an empty +string to define the default queue. +If the messages are not currently located in the default queue, +a &%-qG%& option will be required to define the source queue. +.wen + .vitem &%-Mmad%&&~<&'message&~id'&>&~<&'message&~id'&>&~... .oindex "&%-Mmad%&" .cindex "delivery" "cancelling all" @@ -6109,9 +6127,6 @@ dnslookup: domains = ! +local_domains transport = remote_smtp ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8 -.ifdef _HAVE_DNSSEC - dnssec_request_domains = * -.endif no_more .endd The &%domains%& option behaves as per smarthost, above. @@ -6262,9 +6277,6 @@ Two remote transports and four local transports are defined. remote_smtp: driver = smtp message_size_limit = ${if > {$max_received_linelength}{998} {1}{0}} -.ifdef _HAVE_DANE - hosts_try_dane = * -.endif .ifdef _HAVE_PRDR hosts_try_prdr = * .endif @@ -6665,11 +6677,10 @@ aliases or other indexed data referenced by an MTA. Information about cdb and tools for building the files can be found in several places: .display &url(https://cr.yp.to/cdb.html) -&url(http://www.corpit.ru/mjt/tinycdb.html) +&url(https://www.corpit.ru/mjt/tinycdb.html) &url(https://packages.debian.org/stable/utils/freecdb) &url(https://github.com/philpennock/cdbtools) (in Go) .endd -. --- 2018-09-07: corpit.ru http:-only A cdb distribution is not needed in order to build Exim with cdb support, because the code for reading cdb files is included directly in Exim itself. However, no means of building or testing cdb files is provided with Exim, so @@ -7331,7 +7342,7 @@ with the lookup. With &"strict"& a response from the DNS resolver that is not labelled as authenticated data is treated as equivalent to a temporary DNS error. -The default is &"never"&. +The default is &"lax"&. See also the &$lookup_dnssec_authenticated$& variable. @@ -9377,7 +9388,7 @@ If the ACL returns defer the result is a forced-fail. Otherwise the expansion f .cindex headers "authentication-results:" .cindex authentication "expansion item" This item returns a string suitable for insertion as an -&'Authentication-Results"'& +&'Authentication-Results:'& header line. The given <&'authserv-id'&> is included in the result; typically this will be a domain name identifying the system performing the authentications. @@ -9474,9 +9485,15 @@ set in &_Local/Makefile_&. Once loaded, Exim remembers the dynamically loaded object so that it doesn't reload the same object file in the same Exim process (but of course Exim does start new processes frequently). -There may be from zero to eight arguments to the function. When compiling -a local function that is to be called in this way, &_local_scan.h_& should be -included. The Exim variables and functions that are defined by that API +There may be from zero to eight arguments to the function. + +.new +When compiling +a local function that is to be called in this way, +first &_DLFUNC_IMPL_& should be defined, +and second &_local_scan.h_& should be included. +.wen +The Exim variables and functions that are defined by that API are also available for dynamically loaded functions. The function itself must have the following type: .code @@ -13353,6 +13370,9 @@ or a &%def%& condition. &*Note*&: Under versions of OpenSSL preceding 1.1.1, when a list of more than one file is used for &%tls_certificate%&, this variable is not reliable. +.new +The macro "_TLS_BAD_MULTICERT_IN_OURCERT" will be defined for those versions. +.wen .vitem &$tls_in_peercert$& .vindex "&$tls_in_peercert$&" @@ -13502,6 +13522,19 @@ the transport. .vindex &$tls_out_tlsa_usage$& Bitfield of TLSA record types found. See section &<>&. +.new +.vitem &$tls_in_ver$& +.vindex "&$tls_in_ver$&" +When a message is received from a remote host over an encrypted SMTP connection +this variable is set to the protocol version, eg &'TLS1.2'&. + +.vitem &$tls_out_ver$& +.vindex "&$tls_out_ver$&" +When a message is being delivered to a remote host over an encrypted SMTP connection +this variable is set to the protocol version. +.wen + + .vitem &$tod_bsdinbox$& .vindex "&$tod_bsdinbox$&" The time of day and the date, in the format required for BSD-style mailbox @@ -14691,13 +14724,20 @@ recommended, except when you have no other choice. .cindex "UTF-8" "in domain name" Lots of discussion is going on about internationalized domain names. One camp is strongly in favour of just using UTF-8 characters, and it seems -that at least two other MTAs permit this. This option allows Exim users to -experiment if they wish. +that at least two other MTAs permit this. +This option allows Exim users to experiment if they wish. If it is set true, Exim's domain parsing function allows valid UTF-8 multicharacters to appear in domain name components, in addition to -letters, digits, and hyphens. However, just setting this option is not -enough; if you want to look up these domain names in the DNS, you must also +letters, digits, and hyphens. + +.new +If Exim is built with internationalization support +and the SMTPUTF8 ESMTP option is in use (see chapter &<>&) +this option can be left as default. +.wen +Without that, +if you want to look up such domain names in the DNS, you must also adjust the value of &%dns_check_names_pattern%& to match the extended form. A suitable setting is: .code @@ -16262,7 +16302,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. -.option openssl_options main "string list" "+no_sslv2 +no_sslv3 +single_dh_use +no_ticket" +.option openssl_options main "string list" "+no_sslv2 +no_sslv3 +single_dh_use +no_ticket +no_renegotiation" .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, @@ -16452,6 +16492,8 @@ and from which pipeline early-connection (before MAIL) SMTP commands are acceptable. When used, the pipelining saves on roundtrip times. +See also the &%hosts_pipe_connect%& smtp transport option. + Currently the option name &"X_PIPE_CONNECT"& is used. .wen @@ -16727,6 +16769,7 @@ received_header_text = Received: \ ${if def:sender_helo_name {(helo=$sender_helo_name)\n\t}}}}\ by $primary_hostname \ ${if def:received_protocol {with $received_protocol }}\ + ${if def:tls_ver { ($tls_ver)}}\ ${if def:tls_in_cipher_std { tls $tls_in_cipher_std\n\t}}\ (Exim $version_number)\n\t\ ${if def:sender_address \ @@ -17676,9 +17719,9 @@ separator in the usual way (&<>&) to avoid confusion under IP &*Note*&: Under versions of OpenSSL preceding 1.1.1, when a list of more than one file is used, the &$tls_in_ourcert$& variable is unreliable. - -&*Note*&: OCSP stapling is not usable under OpenSSL -when a list of more than one file is used. +.new +The macro "_TLS_BAD_MULTICERT_IN_OURCERT" will be defined for those versions. +.wen If the option contains &$tls_out_sni$& and Exim is built against OpenSSL, then if the OpenSSL build supports TLS extensions and the TLS client sends the @@ -17729,7 +17772,14 @@ larger prime than requested. The value of this option is expanded and indicates the source of DH parameters to be used by Exim. -&*Note: The Exim Maintainers strongly recommend using a filename with site-generated +.new +This option is ignored for GnuTLS version 3.6.0 and later. +The library manages parameter negotiation internally. +.wen + +&*Note: The Exim Maintainers strongly recommend, +for other TLS library versions, +using a filename with site-generated local DH parameters*&, which has been supported across all versions of Exim. The other specific constants available are a fallback so that even when "unconfigured", Exim can offer Perfect Forward Secrecy in older ciphersuites in TLS. @@ -17824,12 +17874,37 @@ status proof for the server's certificate, as obtained from the Certificate Authority. Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later). +.new +The macro "_HAVE_TLS_OCSP" will be defined for those versions. +.wen -For GnuTLS 3.5.6 or later the expanded value of this option can be a list +.new +For OpenSSL 1.1.0 or later, and +.wen +for GnuTLS 3.5.6 or later the expanded value of this option can be a list of files, to match a list given for the &%tls_certificate%& option. The ordering of the two lists must match. +.new +The macro "_HAVE_TLS_OCSP_LIST" will be defined for those versions. +.wen -The file(s) should be in DER format +.new +The file(s) should be in DER format, +except for GnuTLS 3.6.3 or later +or for OpenSSL, +when an optional filetype prefix can be used. +The prefix must be one of "DER" or "PEM", followed by +a single space. If one is used it sets the format for subsequent +files in the list; the initial format is DER. +If multiple proofs are wanted, for multiple chain elements +(this only works under TLS1.3) +they must be coded as a combined OCSP response. + +Although GnuTLS will accept PEM files with multiple separate +PEM blobs (ie. separate OCSP responses), it sends them in the +TLS Certificate record interleaved with the certificates of the chain; +although a GnuTLS client is happy with that, an OpenSSL client is not. +.wen .option tls_on_connect_ports main "string list" unset .cindex SSMTP @@ -18347,7 +18422,7 @@ or for any deliveries caused by this router. You should not set this option unless you really, really know what you are doing. See also the generic transport option of the same name. -.option dnssec_request_domains routers "domain list&!!" unset +.option dnssec_request_domains routers "domain list&!!" * .cindex "MX record" "security" .cindex "DNSSEC" "MX lookup" .cindex "security" "MX lookup" @@ -24536,7 +24611,7 @@ See the &%search_parents%& option in chapter &<>& for more details. -.option dnssec_request_domains smtp "domain list&!!" unset +.option dnssec_request_domains smtp "domain list&!!" * .cindex "MX record" "security" .cindex "DNSSEC" "MX lookup" .cindex "security" "MX lookup" @@ -24715,6 +24790,8 @@ When used, the pipelining saves on roundtrip times. It also turns SMTP into a client-first protocol so combines well with TCP Fast Open. +See also the &%pipelining_connect_advertise_hosts%& main option. + Note: When the facility is used, the transport &%helo_data%& option will be expanded before the &$sending_ip_address$& variable @@ -27998,11 +28075,8 @@ to use GnuTLS, you need to set .code USE_GNUTLS=yes .endd -in Local/Makefile, in addition to -.code -SUPPORT_TLS=yes -.endd -You must also set TLS_LIBS and TLS_INCLUDE appropriately, so that the +in Local/Makefile +you must also set TLS_LIBS and TLS_INCLUDE appropriately, so that the include files and libraries for GnuTLS can be found. There are some differences in usage when using GnuTLS instead of OpenSSL: @@ -29018,7 +29092,8 @@ If DANE is requested and useable (see above) the following transport options are If DANE is not usable, whether requested or not, and CA-anchored verification evaluation is wanted, the above variables should be set appropriately. -Currently the (router or transport options) &%dnssec_request_domains%& must be active and &%dnssec_require_domains%& is ignored. +The router and transport option &%dnssec_request_domains%& must not be +set to "never" and &%dnssec_require_domains%& is ignored. If verification was successful using DANE then the "CV" item in the delivery log line will show as "CV=dane". @@ -34238,8 +34313,10 @@ with translation. This function is used in conjunction with &'smtp_printf()'&, as described below. -.vitem &*void&~smtp_printf(char&~*,&~...)*& -The arguments of this function are like &[printf()]&; it writes to the SMTP +.new +.vitem &*void&~smtp_printf(char&~*,BOOL,&~...)*& +The arguments of this function are almost like &[printf()]&; it writes to the SMTP +.wen output stream. You should use this function only when there is an SMTP output stream, that is, when the incoming message is being received via interactive SMTP. This is the case when &%smtp_input%& is TRUE and &%smtp_batched_input%& @@ -34251,6 +34328,17 @@ is involved. If an SMTP TLS connection is established, &'smtp_printf()'& uses the TLS output function, so it can be used for all forms of SMTP connection. +.new +The second argument is used to request that the data be buffered +(when TRUE) or flushed (along with any previously buffered, when FALSE). +This is advisory only, but likely to save on system-calls and packets +sent when a sequence of calls to the function are made. + +The argument was added in Exim version 4.90 - changing the API. +Nobody noticed until 4.93 was imminent. +A decision on the way forward has not yet been made. +.wen + Strings that are written by &'smtp_printf()'& from within &[local_scan()]& must start with an appropriate response code: 550 if you are going to return LOCAL_SCAN_REJECT, 451 if you are going to return @@ -34268,7 +34356,11 @@ the data returned via the &%return_text%& argument. The added value of using multiple output lines. The &'smtp_printf()'& function does not return any error indication, because it -does not automatically flush pending output, and therefore does not test +does not +.new +guarantee a flush of +.wen +pending output, and therefore does not test the state of the stream. (In the main code of Exim, flushing and error detection is done when Exim is ready for the next SMTP input command.) If you want to flush the output and check for an error (for example, the @@ -40287,8 +40379,12 @@ for more information of what they mean. SPF is a mechanism whereby a domain may assert which IP addresses may transmit messages with its domain in the envelope from, documented by RFC 7208. -For more information on SPF see &url(http://www.openspf.org). -. --- 2018-09-07: still not https +For more information on SPF see &url(http://www.open-spf.org), a static copy of +the &url(http://openspf.org). +. --- 2019-10-28: still not https, open-spf.org is told to be a +. --- web-archive copy of the now dead openspf.org site +. --- See https://www.mail-archive.com/mailop@mailop.org/msg08019.html for a +. --- discussion. Messages sent by a system not authorised will fail checking of such assertions. This includes retransmissions done by traditional forwarders. @@ -40351,7 +40447,7 @@ deny spf = fail message = $sender_host_address is not allowed to send mail from \ ${if def:sender_address_domain \ {$sender_address_domain}{$sender_helo_name}}. \ - Please see http://www.openspf.org/Why?scope=\ + Please see http://www.open-spf.org/Why?scope=\ ${if def:sender_address_domain {mfrom}{helo}};\ identity=${if def:sender_address_domain \ {$sender_address}{$sender_helo_name}};\ @@ -40404,9 +40500,9 @@ In addition to SPF, you can also perform checks for so-called "Best-guess". Strictly speaking, "Best-guess" is not standard SPF, but it is supported by the same framework that enables SPF capability. -Refer to &url(http://www.openspf.org/FAQ/Best_guess_record) +Refer to &url(http://www.open-spf.org/FAQ/Best_guess_record) for a description of what it means. -. --- 2018-09-07: still not https: +. --- 2019-10-28: still not https: To access this feature, simply use the spf_guess condition in place of the spf one. For example: @@ -40489,10 +40585,11 @@ defines the location of a text file of valid top level domains the opendmarc library uses during domain parsing. Maintained by Mozilla, the most current version can be downloaded -from a link at &url(http://publicsuffix.org/list/). +from a link at &url(https://publicsuffix.org/list/, currently pointing +at https://publicsuffix.org/list/public_suffix_list.dat) See also util/renew-opendmarc-tlds.sh script. -The default for the option is currently -/etc/exim/opendmarc.tlds +The default for the option is /etc/exim/opendmarc.tlds. + The &%dmarc_history_file%& option, if set .oindex &%dmarc_history_file%& @@ -41013,7 +41110,9 @@ Events have names which correspond to the point in process at which they fire. The name is placed in the variable &$event_name$& and the event action expansion must check this, as it will be called for every possible event type. +.new The current list of events is: +.wen .display &`dane:fail after transport `& per connection &`msg:complete after main `& per message @@ -41027,6 +41126,7 @@ The current list of events is: &`tcp:close after transport `& per connection &`tls:cert before both `& per certificate in verification chain &`smtp:connect after transport `& per connection +&`smtp:ehlo after transport `& per connection .endd New event types may be added in future. @@ -41053,6 +41153,7 @@ with the event type: &`msg:host:defer `& error string &`tls:cert `& verification chain depth &`smtp:connect `& smtp banner +&`smtp:ehlo `& smtp ehlo response .endd The :defer events populate one extra variable: &$event_defer_errno$&.