LDAP_TABLE(5)                 File Formats Manual                LDAP_TABLE(5)


NAME
       ldap_table - Postfix LDAP client configuration

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
       Postfix 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 "OBSOLETE MAIN.CF PARAMETERS" below for older
       Postfix versions.

       For details about LDAP SSL and STARTTLS, see the section on SSL and
       STARTTLS below.

LIST MEMBERSHIP
       When using LDAP to store lists such as $mynetworks, $mydestination,
       $relay_domains, $local_recipient_maps, etc., it is important to
       understand 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
       $mydestination 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.

       For example, NEVER do this in a map defining $mydestination:

           query_filter = domain=*
           result_attribute = domain

       Do this instead:

           query_filter = domain=%s
           result_attribute = domain

GENERAL LDAP PARAMETERS
       In the text below, default values are given in parentheses.  Note:
       don't use quotes in these variables; at least, not until the Postfix
       configuration routines understand how to deal with quoted strings.

       server_host (default: localhost)
              The name of the host running the LDAP server, e.g.

                  server_host = ldap.example.com

              Depending on the LDAP client library you're using, it should be
              possible to specify multiple servers here, with the library
              trying them in order should the first one fail. It should also
              be possible to give each server in the list a different port
              (overriding server_port below), by naming them like

                  server_host = ldap.example.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.example.com:1444
                              ldap://ldap2.example.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
                              ldaps://ldap.example.com:636

       server_port (default: 389)
              The port the LDAP server listens on, e.g.

                  server_port = 778

       timeout (default: 10 seconds)
              The number of seconds a search can take before timing out, e.g.

                  timeout = 5

       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

              With Postfix 2.2 and later this parameter supports the following
              '%' expansions:

              %%     This is replaced by a literal '%' character.

              %s     This is replaced by the input key.  RFC 2253 quoting is
                     used to make sure that the input key does not add
                     unexpected metacharacters.

              %u     When the input key is an address of the form user@domain,
                     %u is replaced by the (RFC 2253) quoted local part of the
                     address.  Otherwise, %u is replaced by the entire search
                     string.  If the localpart is empty, the search is
                     suppressed and returns no results.

              %d     When the input key is an address of the form user@domain,
                     %d is replaced by the (RFC 2253) quoted domain part of
                     the address.  Otherwise, the search is suppressed and
                     returns no results.

              %[SUD] For the search_base parameter, the upper-case equivalents
                     of the above expansions behave identically to their
                     lower-case counter-parts. With the result_format
                     parameter (previously called result_filter see the OTHER
                     OBSOLETE FEATURES section and below), they expand to the
                     corresponding components of input key rather than the
                     result value.

              %[1-9] The patterns %1, %2, ... %9 are replaced by the
                     corresponding most significant component of the input
                     key's domain. If the input key is user@mail.example.com,
                     then %1 is com, %2 is example and %3 is mail. If the
                     input key is unqualified or does not have enough domain
                     components to satisfy all the specified patterns, the
                     search is suppressed and returns no results.

       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:

              %%     This is replaced by a literal '%' character. (Postfix 2.2
                     and later).

              %s     This is replaced by the input key.  RFC 2254 quoting is
                     used to make sure that the input key does not add
                     unexpected 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.  Otherwise, %u is replaced by the entire search
                     string.  If the localpart is empty, the search is
                     suppressed and returns no results.

              %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.  Otherwise, the search is suppressed and
                     returns no results.

              %[SUD] The upper-case equivalents of the above expansions behave
                     in the query_filter parameter identically to their
                     lower-case counter-parts. With the result_format
                     parameter (previously called result_filter see the OTHER
                     OBSOLETE FEATURES section and below), they expand to the
                     corresponding components of input key rather than the
                     result value.

                     The above %S, %U and %D expansions are available with
                     Postfix 2.2 and later.

              %[1-9] The patterns %1, %2, ... %9 are replaced by the
                     corresponding most significant component of the input
                     key's domain. If the input key is user@mail.example.com,
                     then %1 is com, %2 is example and %3 is mail. If the
                     input key is unqualified or does not have enough domain
                     components to satisfy all the specified patterns, the
                     search is suppressed and returns no results.

                     The above %1, ..., %9 expansions are available with
                     Postfix 2.2 and later.

              The "domain" parameter described below limits the input keys to
              addresses in matching domains. When the "domain" parameter is
              non-empty, LDAP queries for unqualified addresses or addresses
              in non-matching domains are suppressed and return no results.

              NOTE: DO NOT put quotes around the query_filter parameter.

       result_format (default: %s)
              Called result_filter in Postfix releases prior to 2.2.  Format
              template applied to result attributes. Most commonly used to
              append (or prepend) text to the result. This parameter supports
              the following '%' expansions:

              %%     This is replaced by a literal '%' character. (Postfix 2.2
                     and later).

              %s     This is replaced by the value of the result attribute.
                     When result is empty it is skipped.

              %u     When the result attribute value is an address of the form
                     user@domain, %u is replaced by the local part of the
                     address. When the result has an empty localpart it is
                     skipped.

              %d     When a result attribute value is an address of the form
                     user@domain, %d is replaced by the domain part of the
                     attribute value. When the result is unqualified it is
                     skipped.

              %[SUD1-9]
                     The upper-case and decimal digit expansions interpolate
                     the parts of the input key rather than the result. Their
                     behavior is identical to that described with
                     query_filter, and in fact because the input key is known
                     in advance, lookups whose key does not contain all the
                     information specified in the result template are
                     suppressed and return no results.

                     The above %S, %U, %D and %1, ..., %9 expansions are
                     available with Postfix 2.2 and later.

              For example, using "result_format = smtp:[%s]" allows one to use
              a mailHost attribute as the basis of a transport(5) table. After
              applying the result format, 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.

              This parameter was called result_filter in Postfix releases
              prior to 2.2. If no "result_format" is specified, the value of
              "result_filter" will be used instead before resorting to the
              default value. This provides compatibility with old
              configuration files.

              NOTE: DO NOT put quotes around the result format!

       domain (default: no domain list)
              This is a list of domain names, paths to files, or "type:table"
              databases. 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.

              This feature is available in Postfix 1.0 and later.

       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

              Don't rely on the default value ("maildrop"). Set the
              result_attribute explicitly in all ldap table configuration
              files. This is particularly relevant when no result_attribute is
              applicable, e.g. cases in which leaf_result_attribute and/or
              terminal_result_attribute are used instead. The default value is
              harmless if "maildrop" is also listed as a leaf or terminal
              result attribute, but it is best to not leave this to chance.

       special_result_attribute (default: empty)
              The attribute(s) of directory entries that can contain DNs or
              RFC 2255 LDAP URLs. If found, a recursive search is performed to
              retrieve the entry referenced by the DN, or the entries matched
              by the URL query.

                  special_result_attribute = memberdn

              DN recursion retrieves the same result_attributes as the main
              query, including the special attributes for further recursion.

              URL processing retrieves only those attributes that are included
              in both the URL definition and as result attributes (ordinary,
              special, leaf or terminal) in the Postfix table definition.  If
              the URL lists any of the table's special result attributes,
              these are retrieved and used recursively. A URL that does not
              specify any attribute selection, is equivalent (RFC 2255) to a
              URL that selects all attributes, in which case the selected
              attributes will be the full set of result attributes in the
              Postfix table.

              If an LDAP URL attribute-descriptor or the corresponding Postfix
              LDAP table result attribute (but not both) uses RFC 2255
              sub-type options ("attr;option"), the attribute requested from
              the LDAP server will include the sub-type option. In all other
              cases, the URL attribute and the table attribute must match
              exactly. Attributes with options in both the URL and the Postfix
              table are requested only when the options are identical. LDAP
              attribute-descriptor options are very rarely used, most LDAP
              users will not need to concern themselves with this level of
              nuanced detail.

       terminal_result_attribute (default: empty)
              When one or more terminal result attributes are found in an LDAP
              entry, all other result attributes are ignored and only the
              terminal result attributes are returned. This is useful for
              delegating expansion of group members to a particular host, by
              using an optional "maildrop" attribute on selected groups to
              route the group to a specific host, where the group is expanded,
              possibly via mailing-list manager or other special processing.

                  result_attribute =
                  terminal_result_attribute = maildrop

              When using terminal and/or leaf result attributes, the
              result_attribute is best set to an empty value when it is not
              used, or else explicitly set to the desired value, even if it is
              the default value "maildrop".

              This feature is available with Postfix 2.4 or later.

       leaf_result_attribute (default: empty)
              When one or more special result attributes are found in a
              non-terminal (see above) LDAP entry, leaf result attributes are
              excluded from the expansion of that entry. This is useful when
              expanding groups and the desired mail address attribute(s) of
              the member objects obtained via DN or URI recursion are also
              present in the group object. To only return the attribute values
              from the leaf objects and not the containing group, add the
              attribute to the leaf_result_attribute list, and not the
              result_attribute list, which is always expanded. Note, the
              default value of "result_attribute" is not empty, you may want
              to set it explicitly empty when using "leaf_result_attribute" to
              expand the group to a list of member DN addresses. If groups
              have both member DN references AND attributes that hold multiple
              string valued rfc822 addresses, then the string attributes go in
              "result_attribute".  The attributes that represent the email
              addresses of objects referenced via a DN (or LDAP URI) go in
              "leaf_result_attribute".

                  result_attribute = memberaddr
                  special_result_attribute = memberdn
                  terminal_result_attribute = maildrop
                  leaf_result_attribute = mail

              When using terminal and/or leaf result attributes, the
              result_attribute is best set to an empty value when it is not
              used, or else explicitly set to the desired value, even if it is
              the default value "maildrop".

              This feature is available with Postfix 2.4 or later.

       scope (default: sub)
              The LDAP search scope: sub, base, or one.  These translate into
              LDAP_SCOPE_SUBTREE, LDAP_SCOPE_BASE, and LDAP_SCOPE_ONELEVEL.

       bind (default: yes)
              Whether or how to bind to the LDAP server. Newer LDAP
              implementations don't require clients to bind, which saves time.
              Example:

                  # Don't bind
                  bind = no
                  # Use SIMPLE bind
                  bind = yes
                  # Use SASL bind
                  bind = sasl

              Postfix versions prior to 2.8 only support "bind = no" which
              means don't bind, and "bind = yes" which means do a SIMPLE bind.
              Postfix 2.8 and later also supports "bind = SASL" when compiled
              with LDAP SASL support as described in LDAP_README, it also adds
              the synonyms "bind = none" and "bind = simple" for "bind = no"
              and "bind = yes" respectively. See the SASL section below for
              additional parameters available with "bind = sasl".

              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
              support 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
              With "bind = sasl" (see above) the DN may be optional for some
              SASL mechanisms, don't specify a DN if not needed.

       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
              With "bind = sasl" (see above) the password may be optional for
              some SASL mechanisms, don't specify a password if not needed.

       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
              number.

       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 search performed as part of the lookup. A setting of 0
              disables the limit.  Expansion of DN and URL references involves
              nested LDAP queries, each of which is separately subjected to
              this limit.

              Note: even a single LDAP entry can generate multiple lookup
              results, via multiple result attributes and/or multi-valued
              result attributes. This limit caps the per search resource
              utilization on the LDAP server, not the final multiplicity of
              the lookup result. It is analogous to the "-z" option of
              "ldapsearch".

       dereference (default: 0)
              When to dereference LDAP aliases. (Note that this has nothing do
              with Postfix aliases.) The permitted values are those legal for
              the OpenLDAP/UM LDAP implementations:

              0      never

              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 SASL PARAMETERS
       If you're using the OpenLDAP libraries compiled with SASL support,
       Postfix 2.8 and later built with LDAP SASL support as described in
       LDAP_README can authenticate to LDAP servers via SASL.

       This enables authentication to the LDAP server via mechanisms other
       than a simple password. The added flexibility has a cost: it is no
       longer practical to set an explicit timeout on the duration of an LDAP
       bind operation. Under adverse conditions, whether a SASL bind times
       out, or if it does, the duration of the timeout is determined by the
       LDAP and SASL libraries.

       It is best to use tables that use SASL binds via proxymap(8), this way
       the requesting process can time-out the proxymap request. This also
       lets you tailer the process environment by overriding the proxymap(8)
       import_environment setting in master.cf(5). Special environment
       settings may be needed to configure GSSAPI credential caches or other
       SASL mechanism specific options. The GSSAPI credentials used for LDAP
       lookups may need to be different than say those used for the Postfix
       SMTP client to authenticate to remote servers.

       Using SASL mechanisms requires LDAP protocol version 3, the default
       protocol version is 2 for backwards compatibility. You must set
       "version = 3" in addition to "bind = sasl".

       The following parameters are relevant to using LDAP with SASL

       sasl_mechs (default: empty)
              Space separated list of SASL mechanism(s) to try.

       sasl_realm (default: empty)
              SASL Realm to use, if applicable.

       sasl_authz_id (default: empty)
              The SASL authorization identity to assert, if applicable.

       sasl_minssf (default: 0)
              The minimum required sasl security factor required to establish
              a connection.

LDAP SSL AND STARTTLS PARAMETERS
       If you're using the OpenLDAP libraries compiled with SSL support,
       Postfix 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.example.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
       explicitly with:

           version = 3

       If any of the Postfix programs querying the map is configured in
       master.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
              automatically when the TCP connection is opened).

       tls_ca_cert_dir (No default; set either this or tls_ca_cert_file)
              Directory containing X509 Certification 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 files are looked up by the CA subject name hash value, which
              must hence be available. If more than one CA certificate with
              the same name hash value exist, the extension must be different
              (e.g. 9d66eef0.0, 9d66eef0.1 etc). The search is performed in
              the ordering of the extension number, regardless of other
              properties of the certificates. Use the c_rehash utility (from
              the OpenSSL distribution) to create the necessary links.

       tls_ca_cert_file (No default; set either this or tls_ca_cert_dir)
              File containing the X509 Certification Authority certificates in
              PEM format which are to be recognized by the client in SSL/TLS
              connections. This setting takes precedence over tls_ca_cert_dir.

       tls_cert (No default; you must set this)
              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.  The
              supported values are no and yes.

              With no, the server certificate trust chain is not checked, but
              with OpenLDAP prior to 2.1.13, the name in the server
              certificate must still match the LDAP server name. With OpenLDAP
              2.0.0 to 2.0.11 the server name is not necessarily what you
              specified, rather it is determined (by reverse lookup) from the
              IP address of the LDAP server connection. With OpenLDAP prior to
              2.0.13, subjectAlternativeName extensions in the LDAP server
              certificate are ignored: the server name must match the subject
              CommonName. The no setting corresponds to the never value of
              TLS_REQCERT in LDAP client configuration files.

              Don't use TLS with OpenLDAP 2.0.x (and especially with x <= 11)
              if you can avoid it.

              With yes, the server certificate must be issued by a trusted CA,
              and not be expired. The LDAP server name must match one of the
              name(s) found in the certificate (see above for OpenLDAP library
              version dependent behavior). The yes setting corresponds to the
              demand value of TLS_REQCERT in LDAP client configuration files.

              The "try" and "allow" values of TLS_REQCERT have no equivalents
              here. They are not available with OpenLDAP 2.0, and in any case
              have questionable security properties. Either you want TLS
              verified LDAP connections, or you don't.

              The yes value only works correctly with Postfix 2.5 and later,
              or with OpenLDAP 2.0. Earlier Postfix releases or later OpenLDAP
              releases don't work together with this setting. Support for LDAP
              over TLS was added to Postfix based on the OpenLDAP 2.0 API.

       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.example.com
           search_base = dc=example, 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
       listening at port 389 on ldap.example.com.  It will bind anonymously,
       search for any directory entries whose mailacceptinggeneralid attribute
       is "ldapuser", 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.

OBSOLETE MAIN.CF PARAMETERS
       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
       definition, 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.

OTHER OBSOLETE FEATURES

       result_filter (No default)
              For backwards compatibility with the pre 2.2 LDAP clients,
              result_filter can for now be used instead of result_format, when
              the latter parameter is not also set.  The new name better
              reflects the function of the parameter. This compatibility
              interface may be removed in a future release.

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)
       Carsten Hoeger, Hery Rakotoarisoa, John Hensley, Keith Stevenson,
       LaMont Jones, Liviu Daia, Manuel Guesdon, Mike Mattice, Prabhat K
       Singh, Sami Haahtinen, Samuel Tardieu, Victor Duchovni, and many
       others.

                                                                 LDAP_TABLE(5)