. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.89"
+.set previousversion "4.90"
.include ./local_params
.set ACL "access control lists (ACLs)"
the same lookup again. Otherwise, because each Exim process caches the results
of lookups, you will just get the same result as before.
-.new
Macro processing is done on lines before string-expansion: new macros can be
defined and macros will be expanded.
Because macros in the config file are often used for secrets, those are only
available to admin users.
-.wen
.vitem &%-bem%&&~<&'filename'&>
.oindex "&%-bem%&"
by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
host to which Exim is connected supports TLS encryption.
-.new
.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&>
.oindex "&%-MCt%&"
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
connection is being proxied by a parent process for handling TLS encryption.
The arguments give the local address and port being proxied, and the TLS cipher.
-.wen
.vitem &%-Mc%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
.oindex "&%-Mc%&"
hexadecimal digits. There may be fewer than eight components if an empty
component (adjacent colons) is present. Only one empty component is permitted.
-.new
&*Note*&: The checks used to be just on the form of the address; actual numerical
values were not considered. Thus, for example, 999.999.999.999 passed the IPv4
check.
This is no longer the case.
-.wen
The main use of these tests is to distinguish between IP addresses and
host names, or between IPv4 and IPv6 addresses. For example, you could use
.vindex "&$config_file$&"
The name of the main configuration file Exim is using.
+.vitem &$dkim_verify_status$& &&&
+Results of DKIM verification.
+For details see chapter &<<CHAPdkim>>&.
+
.vitem &$dkim_cur_signer$& &&&
- &$dkim_verify_status$& &&&
&$dkim_verify_reason$& &&&
&$dkim_domain$& &&&
&$dkim_identity$& &&&
This variable contains the number of bytes in the longest line that was
received as part of the message, not counting the line termination
character(s).
-.new
It is not valid if the &%spool_files_wireformat%& option is used.
-.wen
.vitem &$message_age$&
.cindex "message" "age of"
separates the body from the header. Newlines are included in the count. See
also &$message_size$&, &$body_linecount$&, and &$body_zerocount$&.
-.new
If the spool file is wireformat
(see the &%spool_files_wireformat%& main option)
the CRLF line-terminators are included in the count.
-.wen
.vitem &$message_exim_id$&
.vindex "&$message_exim_id$&"
In the MAIL and RCPT ACLs, the value is zero because at that stage the
message has not yet been received.
-.new
This variable is not valid if the &%spool_files_wireformat%& option is used.
-.wen
.vitem &$message_size$&
.cindex "size" "of message"
space removed. Following the introduction of &$smtp_command$&, this variable is
somewhat redundant, but is retained for backwards compatibility.
-.new
.vitem &$smtp_command_history$&
.cindex SMTP "command history"
.vindex "&$smtp_command_history$&"
A comma-separated list (with no whitespace) of the most-recent SMTP commands
received, in time-order left to right. Only a limited number of commands
are remembered.
-.wen
.vitem &$smtp_count_at_connection_start$&
.vindex "&$smtp_count_at_connection_start$&"
&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator,
or a &%def%& condition.
+&*Note*&: Under current versions of OpenSSL, when a list of more than one
+file is used for &%tls_certificate%&, this variable is not reliable.
+
.vitem &$tls_in_peercert$&
.vindex "&$tls_in_peercert$&"
This variable refers to the certificate presented by the peer of an
these hosts.
Hosts may use the BDAT command as an alternate to DATA.
-.new
.option commandline_checks_require_admin main boolean &`false`&
.cindex "restricting access to features"
This option restricts various basic checking features to require an
administrative user.
This affects most of the &%-b*%& options, such as &%-be%&.
-.wen
.option debug_store main boolean &`false`&
.cindex debugging "memory corruption"
By using this option to override the compiled-in path, it is possible to run
tests of Exim without using the standard spool.
-.new
.option spool_wireformat main boolean false
.cindex "spool directory" "file formats"
If this option is set, Exim may for some messages use an alternate format
Using any of the ACL conditions noted will negate the reception benefit
(as a Unix-mbox-format file is contructed for them).
The transimssion benefit is maintained.
-.wen
.option sqlite_lock_timeout main time 5s
.cindex "sqlite lookup type" "lock timeout"
is not required the &%tls_advertise_hosts%& option should be set empty.
-.option tls_certificate main string&!! unset
+.option tls_certificate main string list&!! unset
.cindex "TLS" "server certificate; location of"
.cindex "certificate" "server, location of"
-The value of this option is expanded, and must then be the absolute path to a
-file which contains the server's certificates. The server's private key is also
+The value of this option is expanded, and must then be a list of absolute paths to
+files which contains the server's certificates. Commonly only one file is
+needed.
+The server's private key is also
assumed to be in this file if &%tls_privatekey%& is unset. See chapter
&<<CHAPTLS>>& for further details.
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.
+
+&*Note*&: Under current versions of OpenSSL, when a list of more than one
+file is used, the &$tls_in_ourcert$& veriable is unreliable.
+
+&*Note*&: OCSP stapling is not usable under OpenSSL
+when a list of more than one file is used.
+
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
Server Name Indication extension, then this option and others documented in
.cindex "TLS" "server certificate revocation list"
.cindex "certificate" "revocation list for server"
This option specifies a certificate revocation list. The expanded value must
-be the name of a file that contains a CRL in PEM format.
+be the name of a file that contains CRLs in PEM format.
+
+.new
+Under OpenSSL the option can specify a directory with CRL files.
+
+&*Note: Under OpenSSL the option must, if given, supply a CRL
+for each signing element of the certificate chain (i.e. all but the leaf).
+For the file variant this can be multiple PEM blocks in the one file.
+.wen
See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later).
+.new
+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.
+.wen
+
.option tls_on_connect_ports main "string list" unset
.cindex SSMTP
-.option tls_privatekey main string&!! unset
+.option tls_privatekey main string list&!! unset
.cindex "TLS" "server private key; location of"
-The value of this option is expanded, and must then be the absolute path to a
-file which contains the server's private key. If this option is unset, or if
+The value of this option is expanded, and must then be a list of absolute paths to
+files which contains the server's private keys.
+If this option is unset, or if
the expansion is forced to fail, or the result is an empty string, the private
key is assumed to be in the same file as the server's certificates. See chapter
&<<CHAPTLS>>& for further details.
message on the same connection. See section &<<SECTmulmessam>>& for an
explanation of when this might be needed.
-.new
.option hosts_noproxy_tls smtp "host list&!!" *
.cindex "TLS" "passing connection"
.cindex "multiple SMTP deliveries"
the SMTP connection from and to the new process and any subsequents.
The new process has no access to TLS information, so cannot include it in
logging.
-.wen
(If an API is found to let OpenSSL be configured in this way,
let the Exim Maintainers know and we'll likely use it).
.next
+With GnuTLS, if an explicit list is used for the &%tls_privatekey%& main option
+main option, it must be ordered to match the &%tls_certificate%& list.
+.next
Some other recently added features may only be available in one or the other.
This should be documented with the feature. If the documentation does not
explicitly state that the feature is infeasible in the other TLS
{HIGH:!MD5:!SHA1}}
.endd
+This example will prefer ECDSA-authenticated ciphers over RSA ones:
+.code
+tls_require_ciphers = ECDSA:RSA:!COMPLEMENTOFDEFAULT
+.endd
.section "Requiring specific ciphers or other parameters in GnuTLS" &&&
Further protection requires some further configuration at the server end.
-It is rumoured that all existing clients that support TLS/SSL use RSA
-encryption. To make this work you need to set, in the server,
+To make TLS work you need to set, in the server,
.code
tls_certificate = /some/file/name
tls_privatekey = /some/file/name
certificates that need to be sent to the client to enable it to authenticate
the server's certificate.
+For dual-stack (eg. RSA and ECDSA) configurations, these options can be
+colon-separated lists of file paths. Ciphers using given authentication
+algorithms require the presence of a suitable certificate to supply the
+public-key. The server selects among the certificates to present to the
+client depending on the selected cipher, hence the priority ordering for
+ciphers will affect which certificate is used.
+
If you do not understand about certificates and keys, please try to find a
source of this background information, which is not Exim-specific. (There are a
few comments below in section &<<SECTcerandall>>&.)
If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it
specifies a collection of expected server certificates.
-These may be the system default set (depending on library version),
-a file or,
-depending on library version, a directory,
-must name a file or,
-for OpenSSL only (not GnuTLS), a directory.
+These may be
+the system default set (depending on library version),
+a file,
+or (depending on library version) a directory.
The client verifies the server's certificate
against this collection, taking into account any revoked certificates that are
in the list defined by &%tls_crl%&.
"SECTmulmessam"
.cindex "multiple SMTP deliveries with TLS"
.cindex "TLS" "multiple message deliveries"
-.new
Exim sends multiple messages down the same TCP/IP connection by starting up
an entirely new delivery process for each message, passing the socket from
one process to the next. This implementation does not fit well with the use
An older mode of operation can be enabled on a per-host basis by the
&%hosts_noproxy_tls%& option on the &(smtp)& transport. If the host matches
this list the proxy process descibed above is not used; instead Exim
-.wen
shuts down an existing TLS session being run by the delivery process
before passing the socket to a new process. The new process may then
try to start a new TLS session, and if successful, may try to re-authenticate
Note also that headers cannot be
modified by any of the post-data ACLs (DATA, MIME and DKIM).
Headers may be modified by routers (subject to the above) and transports.
-.new
The Received-By: header is generated as soon as the body reception starts,
rather than the traditional time after the full message is received;
this will affect the timestamp.
-.wen
All the usual ACLs are called; if one results in the message being
rejected, all effort spent in delivery (including the costs on
sender when checking recipients. If used indiscriminately, it reduces the
usefulness of callout caching.
-.new
.vitem &*hold*&
This option applies to recipient callouts only. For example:
.code
if the use_sender option is used,
if neither the random nor the use_postmaster option is used,
and if no other callouts intervene.
-.wen
.endlist
If you use any of the parameters that set a non-empty sender for the MAIL
item creates a signed address, and the &%prvscheck%& expansion item checks one.
The syntax of these expansion items is described in section
&<<SECTexpansionitems>>&.
+The validity period on signed addresses is seven days.
As an example, suppose the secret per-address keys are stored in an MySQL
database. A query to look up the key for an address could be defined as a macro
.endd
If you omit the argument, the default values show above are used.
-.new
.vitem &%f-prot6d%&
.cindex "virus scanners" "f-prot6d"
The f-prot6d scanner is accessed using the FPSCAND protocol over TCP.
av_scanner = f-prot6d:localhost 10200
.endd
If you omit the argument, the default values show above are used.
-.wen
.vitem &%fsecure%&
.cindex "virus scanners" "F-Secure"
.code
av_scanner = sock:127.0.0.1 6001:%s:(SPAM|VIRUS):(.*)$
.endd
-.new
Note that surrounding whitespace is stripped from each option, meaning
there is no way to specify a trailing newline.
The socket specifier and both regular-expressions are required.
Default for the commandline is &_%s\n_& (note this does have a trailing newline);
specify an empty element to get this.
-.wen
.vitem &%sophie%&
.cindex "virus scanners" "Sophos and Sophie"
.vlist
.vitem &*int&~body_linecount*&
This variable contains the number of lines in the message's body.
-.new
It is not valid if the &%spool_files_wireformat%& option is used.
-.wen
.vitem &*int&~body_zerocount*&
This variable contains the number of binary zero bytes in the message's body.
-.new
It is not valid if the &%spool_files_wireformat%& option is used.
-.wen
.vitem &*unsigned&~int&~debug_selector*&
This variable is set to zero when no debugging is taking place. Otherwise, it
flagged with &`->`& instead of &`=>`&. When two or more messages are delivered
down a single SMTP connection, an asterisk follows the IP address in the log
lines for the second and subsequent messages.
-.new
When two or more messages are delivered down a single TLS connection, the
DNS and some TLS-related information logged for the first message delivered
will not be present in the log lines for the second and subsequent messages.
TLS cipher information is still available.
-.wen
.cindex "delivery" "cutthrough; logging"
.cindex "cutthrough" "logging"
&%lost_incoming_connection%&: A log line is written when an incoming SMTP
connection is unexpectedly dropped.
.next
-.new
.cindex "log" "millisecond timestamps"
.cindex millisecond logging
.cindex timstamps "millisecond, in logs"
&%millisec%&: Timestamps have a period and three decimal places of finer granularity
appended to the seconds value.
-.wen
.next
.cindex "log" "outgoing interface"
.cindex "log" "local interface"
unprivileged), Exim must be built to allow group read access to its spool
files.
-.new
By default, regular users are trusted to perform basic testing and
introspection commands, as themselves. This setting can be tightened by
setting the &%commandline_checks_require_admin%& option.
This affects most of the checking options,
such as &%-be%& and anything else &%-b*%&.
-.wen
.section "Spool files" "SECID275"
-J file and uses it to update the -H file before starting the next delivery
attempt.
-.new
Files whose names end with -K or .eml may also be seen in the spool.
These are temporaries used for DKIM or malware processing, when that is used.
They should be tidied up by normal operations; any old ones are probably
relics of crashes and can be removed.
-.wen
.section "Format of the -H file" "SECID282"
.cindex "uid (user id)" "in spool file"
If a message was scanned by SpamAssassin, this is present. It records the value
of &$spam_score_int$&.
-.new
.vitem &%-spool_file_wireformat%&
The -D file for this message is in wire-format (for ESMTP CHUNKING)
rather than Unix-format.
The line-ending is CRLF rather than newline.
There is still, however, no leading-dot-stuffing.
-.wen
.vitem &%-tls_certificate_verified%&
A TLS certificate was received from the client that sent this message, and the
.ecindex IIDforspo2
.ecindex IIDforspo3
-.new
.section "Format of the -D file" "SECID282a"
The data file is traditionally in Unix-standard format: lines are ended with
an ASCII newline character.
ESMTP CHUNKING option, meaning lower processing overhead.
Lines are terminated with an ASCII CRLF pair.
There is no dot-stuffing (and no dot-termination).
-.wen
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
.option dkim_domain smtp string list&!! unset
The domain(s) you want to sign with.
-.new
After expansion, this can be a list.
Each element in turn is put into the &%$dkim_domain%& expansion variable
while expanding the remaining signing options.
-.wen
If it is empty after expansion, DKIM signing is not done.
.option dkim_selector smtp string list&!! unset
This sets the key selector string.
-.new
After expansion, which can use &$dkim_domain$&, this can be a list.
Each element in turn is put in the expansion
variable &%$dkim_selector%& which may be used in the &%dkim_private_key%&
option along with &%$dkim_domain%&.
If the option is empty after expansion, DKIM signing is not done for this domain.
-.wen
.option dkim_private_key smtp string&!! unset
This sets the private key to use.
.endlist
If the option is empty after expansion, DKIM signing is not done.
-.new
.option dkim_hash smtp string&!! sha256
Can be set alternatively to &"sha1"& to use an alternate hash
method. Note that sha1 is now condidered insecure, and deprecated.
syntax of this optional tag to a mail address, with possibly-empty
local part, an @, and a domain identical to or subdomain of the "d="
tag value. Note that Exim does not check the value.
-.wen
.option dkim_canon smtp string&!! unset
This option sets the canonicalization method used when signing a message.
.option dkim_sign_headers smtp string&!! "see below"
If set, this option must expand to a colon-separated
list of header names.
-.new
Headers with these names, or the absence or such a header, will be included
in the message signature.
When unspecified, the header names listed in RFC4871 will be used,
If a '+' prefix if used, all headers that are present with this name
will be signed, and one signtature added for a missing header with the
name will be appended.
-.wen
.section "Verifying DKIM signatures in incoming mail" "SECID514"
If a domain or identity is listed several times in the (expanded) value of
&%dkim_verify_signers%&, the ACL is only called once for that domain or identity.
+If multiple signatures match a domain (or identity), the ACL is called once
+for each matching signature.
+
Inside the &%acl_smtp_dkim%&, the following expansion variables are
available (from most to least important):
&%dkim_verify_signers%& (see above).
.vitem &%$dkim_verify_status%&
-A string describing the general status of the signature. One of
+Within the DKIM ACL,
+a string describing the general status of the signature. One of
.ilist
&%none%&: There is no signature in the message for the current domain or
identity (as reflected by &%$dkim_cur_signer%&).
&%pass%&: The signature passed verification. It is valid.
.endlist
+This variable can be overwritten using an ACL 'set' modifier.
+This might, for instance, be done to enforce a policy restriction on
+hash-method or key-size:
+.code
+ warn condition = ${if eq {$dkim_algo}{rsa-sha1}}
+ condition = ${if eq {$dkim_verify_status}{pass}}
+ logwrite = NOTE: forcing dkim verify fail (was pass)
+ set dkim_verify_status = fail
+ set dkim_verify_reason = hash too weak
+.endd
+
+After all the DKIM ACL runs have completed, the value becomes a
+colon-separated list of the values after each run.
+
.vitem &%$dkim_verify_reason%&
A string giving a little bit more detail when &%$dkim_verify_status%& is either
"fail" or "invalid". One of
DKIM verification. It may of course also mean that the signature is forged.
.endlist
+This variable can be overwritten using an ACL 'set' modifier.
+
.vitem &%$dkim_domain%&
The signing domain. IMPORTANT: This variable is only populated if there is
an actual signature in the message for the current domain or identity (as
before or after the action is associates with. Those which fire before
can be used to affect that action (more on this below).
-.new
The third column in the table above says what section of the configumration
should define the event action.
-.wen
An additional variable, &$event_data$&, is filled with information varying
with the event type:
git://git.exim.org / users / jgh / exim.git / blobdiff