. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.83"
+.set previousversion "4.84"
.include ./local_params
.set ACL "access control lists (ACLs)"
If you have hosts for which you trust RFC1413 and need this
information, you can change this.
-This line enables an efficiency SMTP option. It is negociated by clients
+This line enables an efficiency SMTP option. It is negotiated by clients
and not expected to cause problems but can be disabled if needed.
.code
prdr_enable = true
It is permitted to specify a space as the separator character. Further
white space is ignored.
+.section "Dnsdb lookup modifiers" "SECTdnsdb_mod"
+.cindex "dnsdb modifiers"
+.cindex "modifiers" "dnsdb"
+.cindex "options" "dnsdb"
+Modifiers for &(dnsdb)& lookups are givien by optional keywords,
+each followed by a comma,
+that may appear before the record type.
+
+The &(dnsdb)& lookup fails only if all the DNS lookups fail. If there is a
+temporary DNS error for any of them, the behaviour is controlled by
+a defer-option modifier.
+The possible keywords are
+&"defer_strict"&, &"defer_never"&, and &"defer_lax"&.
+With &"strict"& behaviour, any temporary DNS error causes the
+whole lookup to defer. With &"never"& behaviour, a temporary DNS error is
+ignored, and the behaviour is as if the DNS lookup failed to find anything.
+With &"lax"& behaviour, all the queries are attempted, but a temporary DNS
+error causes the whole lookup to defer only if none of the other lookups
+succeed. The default is &"lax"&, so the following lookups are equivalent:
+.code
+${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}}
+${lookup dnsdb{a=one.host.com:two.host.com}}
+.endd
+Thus, in the default case, as long as at least one of the DNS lookups
+yields some data, the lookup succeeds.
+
+.cindex "DNSSEC" "dns lookup"
+Use of &(DNSSEC)& is controlled by a dnssec modifier.
+The possible keywords are
+&"dnssec_strict"&, &"dnssec_lax"&, and &"dnssec_never"&.
+With &"strict"& or &"lax"& DNSSEC information is requested
+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"&.
+
+See also the &$lookup_dnssec_authenticated$& variable.
+
+
.section "Pseudo dnsdb record types" "SECID66"
.cindex "MX record" "in &(dnsdb)& lookup"
By default, both the preference value and the host name are returned for
in the same way that multiple DNS records for a single item are handled. A
different separator can be specified, as described above.
-Modifiers for &(dnsdb)& lookups are givien by optional keywords,
-each followed by a comma,
-that may appear before the record type.
-
-The &(dnsdb)& lookup fails only if all the DNS lookups fail. If there is a
-temporary DNS error for any of them, the behaviour is controlled by
-a defer-option modifier.
-The possible keywords are
-&"defer_strict"&, &"defer_never"&, and &"defer_lax"&.
-With &"strict"& behaviour, any temporary DNS error causes the
-whole lookup to defer. With &"never"& behaviour, a temporary DNS error is
-ignored, and the behaviour is as if the DNS lookup failed to find anything.
-With &"lax"& behaviour, all the queries are attempted, but a temporary DNS
-error causes the whole lookup to defer only if none of the other lookups
-succeed. The default is &"lax"&, so the following lookups are equivalent:
-.code
-${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}}
-${lookup dnsdb{a=one.host.com:two.host.com}}
-.endd
-Thus, in the default case, as long as at least one of the DNS lookups
-yields some data, the lookup succeeds.
-
-.cindex "DNSSEC" "dns lookup"
-Use of &(DNSSEC)& is controlled by a dnssec modifier.
-The possible keywords are
-&"dnssec_strict"&, &"dnssec_lax"&, and &"dnssec_never"&.
-With &"strict"& or &"lax"& DNSSEC information is requested
-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"&.
-
-See also the &$lookup_dnssec_authenticated$& variable.
-
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,
.cindex "expansion" "inserting from a socket"
.cindex "socket, use of in expansion"
.cindex "&%readsocket%& expansion item"
-This item inserts data from a Unix domain or Internet socket into the expanded
+This item inserts data from a Unix domain or TCP socket into the expanded
string. The minimal way of using it uses just two arguments, as in these
examples:
.code
values of &$received_ip_address$& and &$received_port$& are saved with any
messages that are received, thus making these variables available at delivery
time.
-
-&*Note:*& There are no equivalent variables for outgoing connections, because
-the values are unknown (unless they are explicitly set by options of the
-&(smtp)& transport).
+For outbound connections see &$sending_ip_address$&.
.vitem &$received_port$&
.vindex "&$received_port$&"
.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 "&$sender_host_authenticated$&"
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:
For earlier versions of GnuTLS
the option must be set to the name of a single file.
+With OpenSSL the certificates specified
+explicitly
+either by file or directory
+are added to those given by the system default location.
+
These certificates should be for the certificate authorities trusted, rather
than the public cert of individual clients. With both OpenSSL and GnuTLS, if
the value is a file then the certificates are sent by Exim as a server to
connecting clients, defining the list of accepted certificate authorities.
Thus the values defined should be considered public data. To avoid this,
-use OpenSSL with a directory.
+use the explicit directory version.
See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
in clear.
-.option tls_try_verify_hosts smtp "host list&!! unset
+.option tls_try_verify_hosts smtp "host list&!!" unset
.cindex "TLS" "server certificate verification"
.cindex "certificate" "verification of server"
This option gives a list of hosts for which, on encrypted connections,
The &%tls_verify_certificates%& option must also be set.
Note that unless the host is in this list
TLS connections will be denied to hosts using self-signed certificates
-when &%tls_verify_certificates%& is set.
+when &%tls_verify_certificates%& is matched.
The &$tls_out_certificate_verified$& variable is set when
certificate verification succeeds.
files.
For earlier versions of GnuTLS the option must be set to the name of a
single file.
+
+With OpenSSL the certificates specified
+explicitly
+either by file or directory
+are added to those given by the system default location.
+
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.
and certificate verification fails the TLS connection is closed.
-.option tls_verify_hosts smtp "host list&!! unset
+.option tls_verify_hosts smtp "host list&!!" unset
.cindex "TLS" "server certificate verification"
.cindex "certificate" "verification of server"
This option gives a list of hosts for which. on encrypted connections,
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.
&%tls_verify_certificates%&
.next
.vindex "&%tls_ocsp_file%&"
-&%tls_verify_certificates%&
+&%tls_ocsp_file%&
.endlist
Great care should be taken to deal with matters of case, various injection
.cindex "&ACL;" "cutthrough routing"
.cindex "cutthrough" "requesting"
This option requests delivery be attempted while the item is being received.
-It is usable in the RCPT ACL and valid only for single-recipient mails forwarded
-from one SMTP connection to another. If a recipient-verify callout connection is
-requested in the same ACL it is held open and used for the data, otherwise one is made
-after the ACL completes.
+
+The option usable in the RCPT ACL.
+If enabled for a message recieved via smtp and routed to an smtp transport,
+and the message has only one recipient,
+then the delivery connection is made while the receiving connection is open
+and data is copied from one to the other.
+
+If a recipient-verify callout connection is subsequently
+requested in the same ACL it is held open and used for the data,
+otherwise one is made after the initial RCPT ACL completes.
Note that routers are used in verify mode,
and cannot depend on content of received headers.
Should the ultimate destination system positively accept or reject the mail,
a corresponding indication is given to the source system and nothing is queued.
If there is a temporary error the item is queued for later delivery in the
-usual fashion. If the item is successfully delivered in cutthrough mode the log line
-is tagged with ">>" rather than "=>" and appears before the acceptance "<="
-line.
+usual fashion. If the item is successfully delivered in cutthrough mode
+the log line is tagged with ">>" rather than "=>" and appears
+before the acceptance "<=" line.
-Delivery in this mode avoids the generation of a bounce mail to a (possibly faked)
+Delivery in this mode avoids the generation of a bounce mail to a
+(possibly faked)
sender when the destination system is doing content-scan based rejection.
.endd
.vitem &%drweb%&
.cindex "virus scanners" "DrWeb"
-The DrWeb daemon scanner (&url(http://www.sald.com/)) interface takes one
-argument, either a full path to a UNIX socket, or an IP address and port
-separated by white space, as in these examples:
+The DrWeb daemon scanner (&url(http://www.sald.com/)) interface
+takes one option,
+either a full path to a UNIX socket,
+or host and port specifiers separated by white space.
+The host may be a name or an IP address; the port is either a
+single number or a pair of numbers with a dash between.
+For example:
.code
av_scanner = drweb:/var/run/drwebd.sock
av_scanner = drweb:192.168.2.20 31337
If you omit the argument, the default path &_/usr/local/drweb/run/drwebd.sock_&
is used. Thanks to Alex Miller for contributing the code for this scanner.
+.vitem &%f-protd%&
+.cindex "virus scanners" "f-protd"
+The f-protd scanner is accessed via HTTP over TCP.
+One argument is taken, being a space-separated hostname and port number
+(or port-range).
+For example:
+.code
+av_scanner = f-protd:localhost 10200-10204
+.endd
+If you omit the argument, the default values show above are used.
+
.vitem &%fsecure%&
.cindex "virus scanners" "F-Secure"
The F-Secure daemon scanner (&url(http://www.f-secure.com)) takes one
git://git.exim.org / exim.git / blobdiff