Postfix manual - ldap_table(5)

    LDAP_TABLE(5)                                       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  parame-
           ters  described  below.  An example is given at the end of
           this manual.

           This configuration method is available with  Postfix  ver-
           sion  2.1  and later.  See the section "BACKWARDS COMPATI-
           BILITY" below for older Postfix 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 accessi-
           ble as the name you've given the source in its definition,
           an underscore, and the name of the parameter.   For  exam-
           ple,  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 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 dis-
           cussion.

           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  $mydestina-
           tion:
               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 parenthe-
           ses.  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.your.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.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 tim-
                  ing 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 '%' expan-
                  sions:

                  %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. 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,
                         %d  is replaced by the entire search string.

                  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.

           result_filter (default: %s)
                  Format  template applied to result attributes. Sup-
                  ports the same expansions as the query_filter,  and
                  can  be  easily  used  to append (or prepend) text.
                  This parameter supports the  following  '%'  expan-
                  sions:

                  %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/search-
                  domains

                  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  direc-
                  tory 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 con-
                  tain  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 query, including the special attributes
                  for further  recursion.  URI  processing  retrieves
                  only  those attributes that are included in the URI
                  definition    and    are    *also*    listed     in
                  "result_attribute".  If  the  URI  lists any of the
                  map's special result  attributes,  these  are  also
                  retrieved and used recursively.

           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  not  to bind to the LDAP server. Newer
                  LDAP implementations don't require clients to bind,
                  which saves time. Example:
                      bind = no

                  If  you do need to bind, you might consider config-
                  uring 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  distin-
                  guished 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  syn-
                  tax, with map parameters in main.cf, it is not pos-
                  sible 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 com-
                  mand. 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 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  query  performed  as part of the
                  lookup. A setting of 0 disables the limit.   Expan-
                  sion  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 multi-
                  ple lookup results, via multiple result  attributes
                  and/or  multi-valued  result attributes. This limit
                  caps the per query 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 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.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 explicitly with:
               version = 3

           If any of the Postfix programs querying the map is config-
           ured 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 connec-
                  tion 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  recog-
                  nized  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 Certificate Authority cer-
                  tificates 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.

           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  listening  at  port  389  on
           ldap.my.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.

    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
           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)