Build: Enable SUPPORT_TLS by default

[exim.git] / doc / doc-docbook / spec.xfpt

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index bb486d678a0e98c638dd397a44ad936ab0c15eb3..856bb0c15756ecc8516effb496a9461eb446eaa5 100644 (file)
--- 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"
 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
 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
 &<<SECThoslispatsikey>>&).
 &*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
 &<<SECThoslispatsikey>>&).

+
+.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
 .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
 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.
 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)&.
 
 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
 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 &<<SECTexpansionitems>>& onwards. Backslash is used as an
 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 &<<SECTexpansionitems>>& 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.
 
 
 returns the SHA-1 hash fingerprint of the certificate.
 
 

-.vitem &*${sha256:*&<&'string'&>&*}*&
+.vitem &*${sha256:*&<&'string'&>&*}*& &&&
+       &*${sha2:*&<&'string'&>&*}*& &&&
+       &*${sha2_<n>:*&<&'string'&>&*}*&

 .cindex "SHA-256 hash"
 .cindex "SHA-256 hash"

+.cindex "SHA-2 hash"

 .cindex certificate fingerprint
 .cindex "expansion" "SHA-256 hashing"
 .cindex "&%sha256%& expansion item"
 .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.
 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.
 
 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_<n>:*&<&'string'&>&*}*&
 
 .vitem &*${sha3:*&<&'string'&>&*}*& &&&
        &*${sha3_<n>:*&<&'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.
 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
 
 .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 "&$version_number$&"
 
 .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 "&$warn_message_delay$&"
 
 .vitem &$warn_message_delay$&
 .vindex "&$warn_message_delay$&"


@@ -15332,6 +15360,14 @@ not also supplied, the gid is taken from the result of &[getpwnam()]& if it is
 used. See chapter &<<CHAPsecurity>>& for a discussion of security issues.
 
 
 used. See chapter &<<CHAPsecurity>>& 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
 .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 +16193,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)&
 transport driver.
 
 
 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,
 .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,


@@ -17553,7 +17589,7 @@ 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
 option in the relevant &(smtp)& transport.
 
 &*Note*&: If you use filenames based on IP addresses, change the list

-separator in the usual way (&<<SECTlistsepchange>>&) >to avoid confusion under IPv6.
+separator in the usual way (&<<SECTlistsepchange>>&) to avoid confusion under IPv6.

 
 &*Note*&: Under versions of OpenSSL preceding 1.1.1,
 when a list of more than one
 
 &*Note*&: Under versions of OpenSSL preceding 1.1.1,
 when a list of more than one


@@ -24556,13 +24592,15 @@ been started will not be passed to a new delivery process for sending another
 message on the same connection. See section &<<SECTmulmessam>>& for an
 explanation of when this might be needed.
 
 message on the same connection. See section &<<SECTmulmessam>>& 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.
 .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
 
 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 +24696,7 @@ 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.
 
 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
 .cindex DANE "transport options"
 .cindex DANE "attempting for certain servers"
 If built with DANE support, Exim  will lookup a


@@ -28307,7 +28345,7 @@ 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"
 .cindex "cipher" "logging"
 .cindex "log" "TLS cipher"
 .cindex "log" "distinguished name"


@@ -30832,7 +30870,7 @@ For SMTP input that does not come over TCP/IP (the &%-bs%& command line
 option), this condition is always true.
 
 
 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.
 .cindex "verifying" "not blind"
 .cindex "bcc recipients, verifying none"
 This condition checks that there are no blind (bcc) recipients in the message.


@@ -30842,6 +30880,11 @@ 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.
 
 &'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.
 
 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.
 


@@ -37001,7 +37044,7 @@ the following table:
 &`F   `&        sender address (on delivery lines)
 &`H   `&        host name and IP address
 &`I   `&        local interface used
 &`F   `&        sender address (on delivery lines)
 &`H   `&        host name and IP address
 &`I   `&        local interface used

-&`id  `&        message id for incoming message
+&`id  `&        message id (from header) for incoming message

 &`K   `&        CHUNKING extension used
 &`L   `&        on &`<=`& and &`=>`& lines: PIPELINING extension used
 &`M8S `&        8BITMIME status for incoming message
 &`K   `&        CHUNKING extension used
 &`L   `&        on &`<=`& and &`=>`& lines: PIPELINING extension used
 &`M8S `&        8BITMIME status for incoming message


@@ -37108,6 +37151,8 @@ selection marked by asterisks:
 &` incoming_port              `&  remote port on <= lines
 &`*lost_incoming_connection   `&  as it says (includes timeouts)
 &` millisec                   `&  millisecond timestamps and RT,QT,DT,D times
 &` incoming_port              `&  remote port on <= lines
 &`*lost_incoming_connection   `&  as it says (includes timeouts)
 &` millisec                   `&  millisecond timestamps and RT,QT,DT,D times

+&`*msg_id                     `&  on <= lines, Message-ID: header value
+&` msg_id_created             `&  on <= lines, Message-ID: header value when one had to be added

 &` outgoing_interface         `&  local interface on => lines
 &` outgoing_port              `&  add remote port to => lines
 &`*queue_run                  `&  start and end queue runs
 &` outgoing_interface         `&  local interface on => lines
 &` outgoing_port              `&  add remote port to => lines
 &`*queue_run                  `&  start and end queue runs


@@ -37291,6 +37336,16 @@ connection is unexpectedly dropped.
 &%millisec%&: Timestamps have a period and three decimal places of finer granularity
 appended to the seconds value.
 .next
 &%millisec%&: Timestamps have a period and three decimal places of finer granularity
 appended to the seconds value.
 .next

+.new
+.cindex "log" "message id"
+&%msg_id%&: The value of the Message-ID: header.
+.next
+&%msg_id_created%&: The value of the Message-ID: header, when one had to be created.
+This will be either because the message is a bounce, or was submitted locally
+(submission mode) without one.
+The field identifier will have an asterix appended: &"id*="&.
+.wen
+.next

 .cindex "log" "outgoing interface"
 .cindex "log" "local interface"
 .cindex "log" "local address and port"
 .cindex "log" "outgoing interface"
 .cindex "log" "local interface"
 .cindex "log" "local address and port"


@@ -37680,6 +37735,11 @@ Match only frozen messages.
 
 .vitem &*-x*&
 Match only non-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:
 .endlist
 
 The following options control the format of the output:


@@ -39534,7 +39594,7 @@ senders).
 .cindex "DKIM" "signing"
 
 For signing to be usable you must have published a DKIM record in DNS.
 .cindex "DKIM" "signing"
 
 For signing to be usable you must have published a DKIM record in DNS.

-Note that RFC 8301 says:
+Note that RFC 8301 (which does not cover EC keys) says:

 .code
 rsa-sha1 MUST NOT be used for signing or verifying.
 
 .code
 rsa-sha1 MUST NOT be used for signing or verifying.
 


@@ -39554,7 +39614,11 @@ These options take (expandable) strings as arguments.
 .option dkim_domain smtp string list&!! unset
 The domain(s) you want to sign with.
 After expansion, this can be a list.
 .option dkim_domain smtp string list&!! unset
 The domain(s) you want to sign with.
 After expansion, this can be a list.

-Each element in turn is put into the &%$dkim_domain%& expansion variable
+Each element in turn,
+.new
+lowercased,
+.wen
+is put into the &%$dkim_domain%& expansion variable

 while expanding the remaining signing options.
 If it is empty after expansion, DKIM signing is not done,
 and no error will result even if &%dkim_strict%& is set.
 while expanding the remaining signing options.
 If it is empty after expansion, DKIM signing is not done,
 and no error will result even if &%dkim_strict%& is set.


@@ -39608,8 +39672,9 @@ Signers MUST use RSA keys of at least 1024 bits for all keys.
 Signers SHOULD use RSA keys of at least 2048 bits.
 .endd
 
 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)
 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)


@@ -39629,10 +39694,12 @@ 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
 
 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:
 
 .option dkim_hash smtp string&!! sha256
 Can be set to any one of the supported hash methods, which are:


@@ -39755,6 +39822,14 @@ dkim_verify_signers = $sender_address_domain:$dkim_signers
 If a domain or identity is listed several times in the (expanded) value of
 &%dkim_verify_signers%&, the ACL is only called once for that domain or identity.
 
 If a domain or identity is listed several times in the (expanded) value of
 &%dkim_verify_signers%&, the ACL is only called once for that domain or identity.
 

+.new
+Note that if the option is set using untrustworthy data
+(such as the From: header)
+care should be taken to force lowercase for domains
+and for the domain part if identities.
+The default setting can be regarded as trustworthy in this respect.
+.wen
+

 If multiple signatures match a domain (or identity), the ACL is called once
 for each matching signature.
 
 If multiple signatures match a domain (or identity), the ACL is called once
 for each matching signature.
 


@@ -40192,6 +40267,8 @@ of the proxy):
 .endd
 If &$proxy_session$& is set but &$proxy_external_address$& is empty
 there was a protocol error.
 .endd
 If &$proxy_session$& is set but &$proxy_external_address$& is empty
 there was a protocol error.

+The variables &$sender_host_address$& and &$sender_host_port$&
+will have values for the actual client system, not the proxy.

 
 Since the real connections are all coming from the proxy, and the
 per host connection tracking is done before Proxy Protocol is
 
 Since the real connections are all coming from the proxy, and the
 per host connection tracking is done before Proxy Protocol is