Recognised RDN type labels include "CN", "O", "OU" and "DC".
The field selectors marked as "time" above
-may output a number of seconds since epoch
-if the modifier "int" is used.
+take an optional modifier of "int"
+for which the result is the number of seconds since epoch.
+Otherwise the result is a human-readable string
+in the timezone selected by the main "timezone" option.
The field selectors marked as "list" above return a list,
newline-separated by default,
.vitem &$sender_host_address$&
.vindex "&$sender_host_address$&"
-When a message is received from a remote host, this variable contains that
-host's IP address. For locally submitted messages, it is empty.
+When a message is received from a remote host using SMTP,
+this variable contains that
+host's IP address. For locally non-SMTP submitted messages, it is empty.
.vitem &$sender_host_authenticated$&
.vindex "&$sender_host_authenticated$&"
or external command, as described above. It is also used during a
&*reduce*& expansion.
+.vitem &$verify_mode$&
+.vindex "&$verify_mode$&"
+While a router or transport is being run in verify mode
+or for cutthrough delivery,
+contains "S" for sender-verification or "R" for recipient-verification.
+Otherwise, empty.
+
.vitem &$version_number$&
.vindex "&$version_number$&"
The version number of Exim.
adjusted lightly. An unrecognised item will be detected at startup, by
invoking Exim with the &%-bV%& flag.
+The option affects Exim operating both as a server and as a client.
+
Historical note: prior to release 4.80, Exim defaulted this value to
"+dont_insert_empty_fragments", which may still be needed for compatibility
with some clients, but which lowers security by increasing exposure to
some now infamous attacks.
-An example:
+Examples:
.code
# Make both old MS and old Eudora happy:
openssl_options = -all +microsoft_big_sslv3_buffer \
+dont_insert_empty_fragments
+
+# Disable older protocol versions:
+openssl_options = +no_sslv2 +no_sslv3
.endd
Possible options may include:
The value of this option is expanded, and must then be the absolute path to
a file containing permitted certificates for clients that
match &%tls_verify_hosts%& or &%tls_try_verify_hosts%&. Alternatively, if you
-are using OpenSSL, you can set &%tls_verify_certificates%& to the name of a
-directory containing certificate files. This does not work with GnuTLS; the
-option must be set to the name of a single file if you are using GnuTLS.
+are using either GnuTLS version 3.3.6 (or later) or OpenSSL,
+you can set &%tls_verify_certificates%& to the name of a
+directory containing certificate files.
+For earlier versions of GnuTLS
+the option must be set to the name of a single file.
These certificates should be for the certificate authorities trusted, rather
than the public cert of individual clients. With both OpenSSL and GnuTLS, if
or testing recipient verification using &%-bv%&.
See section &<<SECTrouprecon>>& for a list of the order in which preconditions
are evaluated.
+See also the &$verify_mode$& variable.
.option verify_sender routers&!? boolean true
or testing sender verification using &%-bvs%&.
See section &<<SECTrouprecon>>& for a list of the order in which preconditions
are evaluated.
+See also the &$verify_mode$& variable.
.ecindex IIDgenoprou1
.ecindex IIDgenoprou2
The Internet standards bodies strongly discourage use of this mode.
-.option retry_include_ip_address smtp boolean true
+.option retry_include_ip_address smtp boolean&!! true
Exim normally includes both the host name and the IP address in the key it
constructs for indexing retry data after a temporary delivery failure. This
means that when one of several IP addresses for a host is failing, it gets
However, in some dialup environments hosts are assigned a different IP address
each time they connect. In this situation the use of the IP address as part of
the retry key leads to undesirable behaviour. Setting this option false causes
-Exim to use only the host name. This should normally be done on a separate
-instance of the &(smtp)& transport, set up specially to handle the dialup
-hosts.
+Exim to use only the host name.
+Since it is expanded it can be made to depend on the host or domain.
.option serialize_hosts smtp "host list&!!" unset
.vindex "&$host_address$&"
The value of this option must be the absolute path to a file containing
permitted server certificates, for use when setting up an encrypted connection.
-Alternatively, if you are using OpenSSL, you can set
+Alternatively,
+if you are using either GnuTLS version 3.3.6 (or later) or OpenSSL,
+you can set
&%tls_verify_certificates%& to the name of a directory containing certificate
-files. This does not work with GnuTLS; the option must be set to the name of a
-single file if you are using GnuTLS. The values of &$host$& and
+files.
+For earlier versions of GnuTLS the option must be set to the name of a
+single file.
+The values of &$host$& and
&$host_address$& are set to the name and address of the server during the
expansion of this option. See chapter &<<CHAPTLS>>& for details of TLS.
.ilist
The &%tls_verify_certificates%& option must contain the name of a file, not the
-name of a directory (for OpenSSL it can be either).
+name of a directory for GnuTLS versions before 3.3.6
+(for later versions, or OpenSSL, it can be either).
.next
The default value for &%tls_dhparam%& differs for historical reasons.
.next
as part of the &[gnutls_priority_init]& function. This is very similar to the
ciphersuite specification in OpenSSL.
-The &%tls_require_ciphers%& option is treated as the GnuTLS priority string.
+The &%tls_require_ciphers%& option is treated as the GnuTLS priority string
+and controls both protocols and ciphers.
The &%tls_require_ciphers%& option is available both as an global option,
controlling how Exim behaves as a server, and also as an option of the
&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string, then the example code)
on that site can be used to test a given string.
+For example:
+.code
+# Disable older versions of protocols
+tls_require_ciphers = NORMAL:%LATEST_RECORD_VERSION:-VERS-SSL3.0
+.endd
+
Prior to Exim 4.80, an older API of GnuTLS was used, and Exim supported three
additional options, "&%gnutls_require_kx%&", "&%gnutls_require_mac%&" and
"&%gnutls_require_protocols%&". &%tls_require_ciphers%& was an Exim list.
These options are, in fact, expanded strings, so you can make them depend on
the identity of the client that is connected if you wish. The first file
contains the server's X509 certificate, and the second contains the private key
-that goes with it. These files need to be readable by the Exim user, and must
-always be given as full path names. They can be the same file if both the
+that goes with it. These files need to be
+PEM format and readable by the Exim user, and must
+always be given as full path names.
+The key must not be password-protected.
+They can be the same file if both the
certificate and the key are contained within it. If &%tls_privatekey%& is not
set, or if its expansion is forced to fail or results in an empty string, this
is assumed to be the case. The certificate file may also contain intermediate
of the option is expanded and must then be the name of a file that contains a
CRL in PEM format.
The downside is that clients have to periodically re-download a potentially huge
-file from every certificate authority the know of.
+file from every certificate authority they know of.
The way with most moving parts at query time is Online Certificate
Status Protocol (OCSP), where the client verifies the certificate
and $acl_narg is set to the count of values.
Previous values of these variables are restored after the call returns.
The name and values are expanded separately.
+Note that spaces in complex expansions which are used as arguments
+will act as argument separators.
If the nested &%acl%& returns &"drop"& and the outer condition denies access,
the connection is dropped. If it returns &"discard"&, the verb must be
Multiple &%headers_remove%& options for a single router or transport can be
specified; the arguments will append to a single header-names list.
Each item is separately expanded.
+Note that colons in complex expansions which are used to
+form all or part of a &%headers_remove%& list
+will act as list separators.
When &%headers_add%& or &%headers_remove%& is specified on a router,
items are expanded at routing time,
git://git.exim.org / users / jgh / exim.git / blobdiff