SYNOPSIS
postmap -q "string" ldap:/etc/postfix/filename
postmap -q - ldap:/etc/postfix/filename <inputfile
DESCRIPTION
The Postfix mail system uses optional tables for address rewriting or
mail routing. These tables are usually in dbm or db format.
Alternatively, lookup tables can be specified as LDAP databases.
In order to use LDAP lookups, define an LDAP source as a lookup table
in main.cf, for example:
alias_maps = ldap:/etc/postfix/ldap-aliases.cf
The file /etc/postfix/ldap-aliases.cf has the same format as the Post-
fix main.cf file, and can specify the parameters described below. An
example is given at the end of this manual.
This configuration method is available with Postfix version 2.1 and
later. See the section "BACKWARDS COMPATIBILITY" below for older Post-
fix versions.
For details about LDAP SSL and STARTTLS, see the section on SSL and
STARTTLS below.
BACKWARDS COMPATIBILITY
For backwards compatibility with Postfix version 2.0 and earlier, LDAP
parameters can also be defined in main.cf. Specify as LDAP source a
name that doesn't begin with a slash or a dot. The LDAP parameters
will then be accessible as the name you've given the source in its def-
inition, an underscore, and the name of the parameter. For example, if
the map is specified as "ldap:ldapsource", the "server_host" parameter
below would be defined in main.cf as "ldapsource_server_host".
Note: with this form, the passwords for the LDAP sources are written in
main.cf, which is normally world-readable. Support for this form will
be removed in a future Postfix version.
LIST MEMBERSHIP
When using LDAP to store lists such as $mynetworks, $mydestination,
$relay_domains, $local_recipient_maps, etc., it is important to under-
stand that the table must store each list member as a separate key. The
table lookup verifies the *existence* of the key. See "Postfix lists
versus tables" in the DATABASE_README document for a discussion.
Do NOT create tables that return the full list of domains in $mydesti-
nation or $relay_domains etc., or IP addresses in $mynetworks.
DO create tables with each matching item as a key and with an arbitrary
value. With LDAP databases it is not uncommon to return the key itself.
The name of the host running the LDAP server, e.g.
server_host = ldap.your.com
Depending on the LDAP client library you're using, it should be
possible to specify multiple servers here, with the library try-
ing them in order should the first one fail. It should also be
possible to give each server in the list a different port (over-
riding server_port below), by naming them like
server_host = ldap.your.com:1444
With OpenLDAP, a (list of) LDAP URLs can be used to specify both
the hostname(s) and the port(s):
server_host = ldap://ldap.your.com:1444
All LDAP URLs accepted by the OpenLDAP library are supported,
including connections over UNIX domain sockets, and LDAP SSL
(the last one provided that OpenLDAP was compiled with support
for SSL):
server_host = ldapi://%2Fsome%2Fpath
server_host = ldaps://ldap.your.com:636
server_port (default: 389)
The port the LDAP server listens on, e.g.
server_port = 778
search_base (No default; you must configure this)
The RFC2253 base DN at which to conduct the search, e.g.
search_base = dc=your, dc=com
timeout (default: 10 seconds)
The number of seconds a search can take before timing out, e.g.
timeout = 5
query_filter (default: mailacceptinggeneralid=%s)
The RFC2254 filter used to search the directory, where %s is a
substitute for the address Postfix is trying to resolve, e.g.
query_filter = (&(mail=%s)(paid_up=true))
This parameter supports the following '%' expansions:
%s This is replaced by the input key. RFC 2254 quoting is
used to make sure that the input key does not add unex-
pected metacharacters.
%u When the input key is an address of the form user@domain,
%u is replaced by the (RFC 2254) quoted local part of the
address. If no domain is specified, %u is replaced by the
entire search string.
%d When the input key is an address of the form user@domain,
%d is replaced by the (RFC 2254) quoted domain part of
the address. When the input key has no domain qualifier,
%s This is replaced by the value of the result attribute.
%u When the result attribute is an address of the form
user@domain, %u is replaced local part of the address, if
the result attribute is unqualified, %u is replaced by
the entire attribute value.
%d When a result attribute is an address of the form
user@domain, %d is replaced by the domain part of the
attribute value. If an attribute value is unqualified %d
is replaced by the entire attribute value.
For example, using "result_filter = smtp:[%s]" allows one to use
a mailHost attribute as the basis of a transport(5) table. After
applying the result filter, multiple values are concatenated as
comma separated strings. The expansion_limit and size_limit
parameters explained below allow one to restrict the number of
values in the result, which is especially useful for maps that
should return a single value.
The default value %s specifies that each attribute value should
be used as is.
NOTE: DO NOT put quotes around the result filter!
domain (default: no domain list)
This is a list of domain names, paths to files, or dictionaries.
When specified, only fully qualified search keys with a *non-
empty* localpart and a matching domain are eligible for lookup:
'user' lookups, bare domain lookups and "@domain" lookups are
not performed. This can significantly reduce the query load on
the LDAP server.
domain = postfix.org, hash:/etc/postfix/searchdomains
It is best not to use LDAP to store the domains eligible for
LDAP lookups.
NOTE: DO NOT define this parameter for local(8) aliases.
result_attribute (default: maildrop)
The attribute(s) Postfix will read from any directory entries
returned by the lookup, to be resolved to an email address.
result_attribute = mailbox,maildrop
special_result_attribute (No default)
The attribute(s) of directory entries that can contain DNs or
URLs. If found, a recursive subsequent search is done using
their values.
special_result_attribute = member
DN recursion retrieves the same result_attributes as the main
ple:
bind = no
If you do need to bind, you might consider configuring Postfix
to connect to the local machine on a port that's an SSL tunnel
to your LDAP server. If your LDAP server doesn't natively sup-
port SSL, put a tunnel (wrapper, proxy, whatever you want to
call it) on that system too. This should prevent the password
from traversing the network in the clear.
bind_dn (default: empty)
If you do have to bind, do it with this distinguished name.
Example:
bind_dn = uid=postfix, dc=your, dc=com
bind_pw (default: empty)
The password for the distinguished name above. If you have to
use this, you probably want to make the map configuration file
readable only by the Postfix user. When using the obsolete
ldap:ldapsource syntax, with map parameters in main.cf, it is
not possible to securely store the bind password. This is
because main.cf needs to be world readable to allow local
accounts to submit mail via the sendmail command. Example:
bind_pw = postfixpw
cache (IGNORED with a warning)
cache_expiry (IGNORED with a warning)
cache_size (IGNORED with a warning)
The above parameters are NO LONGER SUPPORTED by Postfix. Cache
support has been dropped from OpenLDAP as of release 2.1.13.
recursion_limit (default: 1000)
A limit on the nesting depth of DN and URL special result
attribute evaluation. The limit must be a non-zero positive num-
ber.
expansion_limit (default: 0)
A limit on the total number of result elements returned (as a
comma separated list) by a lookup against the map. A setting of
zero disables the limit. Lookups fail with a temporary error if
the limit is exceeded. Setting the limit to 1 ensures that
lookups do not return multiple values.
size_limit (default: $expansion_limit)
A limit on the number of LDAP entries returned by any single
LDAP query performed as part of the lookup. A setting of 0 dis-
ables the limit. Expansion of DN and URL references involves
nested LDAP queries, each of which is separately subjected to
this limit.
1 when searching
2 when locating the base object for the search
3 always
See ldap.h or the ldap_open(3) or ldapsearch(1) man pages for
more information. And if you're using an LDAP package that has
other possible values, please bring it to the attention of the
postfix-users@postfix.org mailing list.
chase_referrals (default: 0)
Sets (or clears) LDAP_OPT_REFERRALS (requires LDAP version 3
support).
version (default: 2)
Specifies the LDAP protocol version to use.
debuglevel (default: 0)
What level to set for debugging in the OpenLDAP libraries.
LDAP SSL AND STARTTLS PARAMETERS
If you're using the OpenLDAP libraries compiled with SSL support, Post-
fix can connect to LDAP SSL servers and can issue the STARTTLS command.
LDAP SSL service can be requested by using a LDAP SSL URL in the
server_host parameter:
server_host = ldaps://ldap.your.com:636
STARTTLS can be turned on with the start_tls parameter:
start_tls = yes
Both forms require LDAP protocol version 3, which has to be set explic-
itly with:
version = 3
If any of the Postfix programs querying the map is configured in mas-
ter.cf to run chrooted, all the certificates and keys involved have to
be copied to the chroot jail. Of course, the private keys should only
be readable by the user "postfix".
The following parameters are relevant to LDAP SSL and STARTTLS:
start_tls (default: no)
Whether or not to issue STARTTLS upon connection to the server.
Don't set this with LDAP SSL (the SSL session is setup automati-
cally when the TCP connection is opened).
tls_ca_cert_dir (No default; set either this or tls_ca_cert_file)
Directory containing X509 Certificate Authority certificates in
PEM format which are to be recognized by the client in SSL/TLS
connections. The files each contain one CA certificate. The
File containing client's X509 certificate to be used by the
client in SSL/ TLS connections.
tls_key (No default; you must set this)
File containing the private key corresponding to the above
tls_cert.
tls_require_cert (default: no)
Whether or not to request server's X509 certificate and check
its validity when establishing SSL/TLS connections.
tls_random_file (No default)
Path of a file to obtain random bits from when /dev/[u]random is
not available, to be used by the client in SSL/TLS connections.
tls_cipher_suite (No default)
Cipher suite to use in SSL/TLS negotiations.
EXAMPLE
Here's a basic example for using LDAP to look up local(8) aliases.
Assume that in main.cf, you have:
alias_maps = hash:/etc/aliases,
ldap:/etc/postfix/ldap-aliases.cf
and in ldap:/etc/postfix/ldap-aliases.cf you have:
server_host = ldap.my.com
search_base = dc=my, dc=com
Upon receiving mail for a local address "ldapuser" that isn't found in
the /etc/aliases database, Postfix will search the LDAP server listen-
ing at port 389 on ldap.my.com. It will bind anonymously, search for
any directory entries whose mailacceptinggeneralid attribute is "lda-
puser", read the "maildrop" attributes of those found, and build a list
of their maildrops, which will be treated as RFC822 addresses to which
the message will be delivered.
SEE ALSO
postmap(1), Postfix lookup table manager
postconf(5), configuration parameters
mysql_table(5), MySQL lookup tables
pgsql_table(5), PostgreSQL lookup tables
README FILES
Use "postconf readme_directory" or "postconf html_directory" to locate
this information.
DATABASE_README, Postfix lookup table overview
LDAP_README, Postfix LDAP client guide
LICENSE
The Secure Mailer license must be distributed with this software.
AUTHOR(S)
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