. the <bookinfo> element must also be updated for each new edition.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.71"
-.set version "4.72"
+.set previousversion "4.72"
+.set version "4.73"
.set ACL "access control lists (ACLs)"
.set I " "
<author><firstname>Exim</firstname><surname>Maintainers</surname></author>
<authorinitials>EM</authorinitials>
<revhistory><revision>
- <revnumber>4.72</revnumber>
- <date>29 May 2010</date>
+ <revnumber>4.73</revnumber>
+ <date>19 Nov 2010</date>
<authorinitials>EM</authorinitials>
</revision></revhistory>
<copyright><year>2009</year><holder>University of Cambridge</holder></copyright>
waiting for it by the time it recovers, and sending them in a single SMTP
connection is clearly beneficial. Whenever a delivery to a remote host is
deferred,
-
.cindex "hints database"
Exim makes a note in its hints database, and whenever a successful
SMTP delivery has happened, it looks to see if any other messages are waiting
.section "Use of tcpwrappers" "SECID27"
+.new
.cindex "tcpwrappers, building Exim to support"
.cindex "USE_TCP_WRAPPERS"
.cindex "TCP_WRAPPERS_DAEMON_NAME"
in &_Local/Makefile_&, or by setting tcp_wrappers_daemon_name in the
configure file. Consult the &'tcpwrappers'& documentation for
further details.
-
+.wen
.section "Including support for IPv6" "SECID28"
+.section "Dynamically loaded lookup module support" "SECTdynamicmodules"
+.cindex "lookup modules"
+.cindex "dynamic modules"
+.cindex ".so building"
+On some platforms, Exim supports not compiling all lookup types directly into
+the main binary, instead putting some into external modules which can be loaded
+on demand.
+This permits packagers to build Exim with support for lookups with extensive
+library dependencies without requiring all users to install all of those
+dependencies.
+Most, but not all, lookup types can be built this way.
+
+Set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
+installed; Exim will only load modules from that directory, as a security
+measure. You will need to set &`CFLAGS_DYNAMIC`& if not already defined
+for your OS; see &_OS/Makefile-Linux_& for an example.
+Some other requirements for adjusting &`EXTRALIBS`& may also be necessary,
+see &_src/EDITME_& for details.
+
+Then, for each module to be loaded dynamically, define the relevant
+&`LOOKUP_`&<&'lookup_type'&> flags to have the value "2" instead of "yes".
+For example, this will build in lsearch but load sqlite and mysql support
+on demand:
+.code
+LOOKUP_LSEARCH=yes
+LOOKUP_SQLITE=2
+LOOKUP_MYSQL=2
+.endd
+
+
.section "The building process" "SECID29"
.cindex "build directory"
Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been
The same output is generated if the Exim binary is called with no options and
no arguments.
+.new
.vitem &%--version%&
.oindex "&%--version%&"
This option is an alias for &%-bV%& and causes version information to be
displayed.
+.wen
.vitem &%-B%&<&'type'&>
.oindex "&%-B%&"
Exim behaves in exactly the same way as it does when receiving a message via
the listening daemon.
+.new
.vitem &%-bmalware%&&~<&'filename'&>
.oindex "&%-bmalware%&"
.cindex "testing", "malware"
The &%-bmalware%& option will not be extended to be more generally useful,
there are better tools for file-scanning. This option exists to help
administrators verify their Exim and AV scanner configuration.
+.wen
.vitem &%-bt%&
.oindex "&%-bt%&"
.cindex "version number of Exim"
This option causes Exim to write the current version number, compilation
number, and compilation date of the &'exim'& binary to the standard output.
-It also lists the DBM library this is being used, the optional modules (such as
+It also lists the DBM library that is being used, the optional modules (such as
specific lookup types), the drivers that are included in the binary, and the
name of the run time configuration file that is in use.
than a recipient address. This affects any rewriting and qualification that
might happen.
+.new
.vitem &%-C%&&~<&'filelist'&>
.oindex "&%-C%&"
.cindex "configuration file" "alternate"
When this option is used by a caller other than root, and the list is different
from the compiled-in list, Exim gives up its root privilege immediately, and
runs with the real and effective uid and gid set to those of the caller.
-However, if a TRUSTED_CONFIG_LIST file is defined in &_Local/Makefile_&, root
-privilege is retained for any configuration file which is listed in that file
-as long as the caller is the Exim user (or the user specified in the
-CONFIGURE_OWNER option, if any).
+However, if a TRUSTED_CONFIG_LIST file is defined in &_Local/Makefile_&, that
+file contains a list of full pathnames, one per line, for configuration files
+which are trusted. Root privilege is retained for any configuration file so
+listed, as long as the caller is the Exim user (or the user specified in the
+CONFIGURE_OWNER option, if any), and as long as the configuration file is
+not writeable by inappropriate users or groups.
Leaving TRUSTED_CONFIG_LIST unset precludes the possibility of testing a
configuration using &%-C%& right through message reception and delivery,
caller is privileged, or unless it is an exotic configuration that does not
require privilege. No check is made on the owner or group of the files
specified by this option.
+.wen
+.new
.vitem &%-D%&<&'macro'&>=<&'value'&>
.oindex "&%-D%&"
.cindex "macro" "setting on command line"
exim '-D ABC = something' ...
.endd
&%-D%& may be repeated up to 10 times on a command line.
+.wen
.vitem &%-d%&<&'debug&~options'&>
.oindex "&%-d%&"
give a colon-separated list of file names, in which case Exim uses the first
existing file in the list.
+.new
.cindex "EXIM_USER"
.cindex "EXIM_GROUP"
.cindex "CONFIGURE_OWNER"
CONFIGURE_FILE is a list, no default is automatically installed. Chapter
&<<CHAPdefconfil>>& is a &"walk-through"& discussion of the default
configuration.
-
+.wen
.section "Using a different configuration file" "SECID40"
If DISABLE_D_OPTION is defined in &_Local/Makefile_&, the use of &%-D%& is
completely disabled, and its use causes an immediate error exit.
+.new
The WHITELIST_D_MACROS option in &_Local/Makefile_& permits the binary builder
to declare certain macro names trusted, such that root privilege will not
necessarily be discarded.
is root, the Exim run-time user, or the CONFIGURE_OWNER, if set. This is a
transition mechanism and is expected to be removed in the future. Acceptable
values for the macros satisfy the regexp: &`^[A-Za-z0-9_/.-]*$`&
+.wen
Some sites may wish to use the same Exim binary on different machines that
share a file system, but to use different configuration files on each machine.
It is permitted to specify a space as the separator character. Further
white space is ignored.
-.new
.cindex "TXT record" "in &(dnsdb)& lookup"
For TXT records with multiple items of data, only the first item is returned,
unless a separator for them is specified using a comma after the separator
.endd
It is permitted to specify a space as the separator character. Further
white space is ignored.
-.wen
.section "Pseudo dnsdb record types" "SECID66"
.cindex "MX record" "in &(dnsdb)& lookup"
random().
+.new
.vitem &*${reverse_ip:*&<&'ipaddr'&>&*}*&
.cindex "expansion" "IP address"
This operator reverses an IP address; for IPv4 addresses, the result is in
.code
4.2.0.192 and 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
.endd
+.wen
.vitem &*${rfc2047:*&<&'string'&>&*}*&
As a special case, the numerical value of an empty string is taken as
zero.
+
+.new
.vitem &*bool&~{*&<&'string'&>&*}*&
.cindex "expansion" "boolean parsing"
.cindex "&%bool%& expansion condition"
.code
${if bool{$acl_m_privileged_sender} ...
.endd
+.wen
+
.vitem &*bool_lax&~{*&<&'string'&>&*}*&
.cindex "expansion" "boolean parsing"
the generic transport option &%message_size_limit%&, which limits the size of
message that an individual transport can process.
+.new
If you use a virus-scanner and set this option to to a value larger than the
maximum size that your virus-scanner is configured to support, you may get
failures triggered by large mails. The right size to configure for the
probably safest to just set it to a little larger than this value. Eg, with a
default Exim message size of 50M and a default ClamAV StreamMaxLength of 10M,
some problems may result.
+.wen
.option move_frozen_messages main boolean false
transport driver.
+.new
.option openssl_options main "string list" +dont_insert_empty_fragments
.cindex "OpenSSL "compatibility options"
This option allows an administrator to adjust the SSL options applied
.code
openssl_options = -all +microsoft_big_sslv3_buffer
.endd
+.wen
.option oracle_servers main "string list" unset
This specifies the transport driver that is to be used when a &%mail%& command
is used in a system filter.
+.new
.option system_filter_user main string unset
.cindex "uid (user id)" "system filter"
If this option is set to root, the system filter is run in the main Exim
If the system filter generates any pipe, file, or reply deliveries, the uid
under which the filter is run is used when transporting them, unless a
transport option overrides.
+.wen
.option tcp_nodelay main boolean true
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.
+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.
+
.option tls_verify_hosts main "host list&!!" unset
.cindex "TLS" "client certificate verification"
If the result is any other value, the router is run (as this is the last
precondition to be evaluated, all the other preconditions must be true).
+.new
This option is unique in that multiple &%condition%& options may be present.
All &%condition%& options must succeed.
+.wen
The &%condition%& option provides a means of applying custom conditions to the
running of routers. Note that in the case of a simple conditional expansion,
.code
condition = ${if >{$message_age}{600}{true}{}}
.endd
+.new
A multiple condition example, which succeeds:
.code
condition = ${if >{$message_age}{600}}
condition = ${if !eq{${lc:$local_part}}{postmaster}}
condition = foobar
.endd
+.wen
If the expansion fails (other than forced failure) delivery is deferred. Some
of the other precondition options are common special cases that could in fact
be specified using &%condition%&.
apply to a command specified as a transport filter.
+.new
.option permit_coredump pipe boolean false
Normally Exim inhibits core-dumps during delivery. If you have a need to get
a core-dump of a pipe command, enable this command. This enables core-dumps
resource consumption can be quite high. Note also that Exim is typically
installed as a setuid binary and most operating systems will inhibit coredumps
of these by default, so further OS-specific action may be required.
+.wen
.option pipe_as_creator pipe boolean false
driver = plaintext
public_name = LOGIN
server_prompts = Username:: : Password::
- server_condition = ${if and{{
+ server_condition = ${if and{{ \
!eq{}{$auth1} }{ \
ldapauth{user="cn=${quote_ldap_dn:$auth1},ou=people,o=example.org" \
pass=${quote:$auth2} \
your resources.
+.new
+.section "The SMTP DKIM ACL" "SECTDKIMACL"
+The &%acl_smtp_dkim%& ACL is available only when Exim is compiled with DKIM support
+enabled (which is the default).
+
+The ACL test specified by &%acl_smtp_dkim%& happens after a message has been
+received, and is executed for each DKIM signature found in a message. If not
+otherwise specified, the default action is to accept.
+
+For details on the operation of DKIM, see chapter &<<CHID12>>&.
+.wen
+
+
.section "The SMTP MIME ACL" "SECID194"
The &%acl_smtp_mime%& option is available only when Exim is compiled with the
content-scanning extension. For details, see chapter &<<CHAPexiscan>>&.
Notice that we put back the lower cased version afterwards, assuming that
is what is wanted for subsequent tests.
+.new
.vitem &*control&~=&~debug/*&<&'options'&>
.cindex "&ACL;" "enabling debug logging"
.cindex "debugging" "enabling from an ACL"
control = debug/opts=+expand+acl
control = debug/tag=.$message_exim_id/opts=+expand
.endd
+.wen
.vitem &*control&~=&~enforce_sync*& &&&
&*control&~=&~no_enforce_sync*&
use the &%demime%& condition (see section &<<SECTdemimecond>>&) before the
&%malware%& condition.
+.new
Beware the interaction of Exim's &%message_size_limit%& with any size limits
imposed by your anti-virus scanner.
+.wen
Here is a very simple scanning example:
.code
&%spam%& condition for its side effects (see the variables below), you can make
it always return &"true"& by appending &`:true`& to the username.
+.new
.cindex "spam scanning" "returned variables"
When the &%spam%& condition is run, it sets up a number of expansion
variables. These variables are saved with the received message, thus they are
available for use at delivery time.
+.wen
.vlist
.vitem &$spam_score$&
and EHLO act as RSET; VRFY, EXPN, ETRN and HELP, act
as NOOP; QUIT quits.
-No policy checking is done for BSMTP input. That is, no ACL is run at anytime.
-In this respect it is like non-SMTP local input.
+Minimal policy checking is done for BSMTP input. Only the non-SMTP
+ACL is run in the same way as for non-SMTP local input.
If an error is detected while reading a message, including a missing &"."& at
the end, Exim gives up immediately. It writes details of the error to the
into the Exim account from running a privileged Exim with an arbitrary
configuration file, and using it to break into other accounts.
.next
+.new
If a non-trusted configuration file (i.e. not the default configuration file
or one which is trusted by virtue of being listed in the TRUSTED_CONFIG_LIST
file) is specified with &%-C%&, or if macros are given with &%-D%& (but see
it re-execs to regain privilege for the delivery, the use of &%-C%& causes
privilege to be lost. However, root can test reception and delivery using two
separate commands.
+.wen
.next
The WHITELIST_D_MACROS build option declares some macros to be safe to override
with &%-D%& if the real uid is one of root, the Exim run-time user or the
+.section "Dynamic module directory" "SECTdynmoddir"
+Any dynamically loadable modules must be installed into the directory
+defined in &`LOOKUP_MODULE_DIR`& in &_Local/Makefile_& for Exim to permit
+loading it.
+
+
+
.section "Use of sprintf()" "SECID279"
.cindex "&[sprintf()]&"
A large number of occurrences of &"sprintf"& in the code are actually calls to
git://git.exim.org / exim.git / blobdiff