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.

           Postfix 2.2 has enhanced query interfaces  for  MySQL  and
           PostgreSQL.   These  include features that were previously
           available only in the Postfix LDAP client. This work  also
           created an opportunity for improvements in the LDAP inter-
           face. The primary compatibility issue is that  result_fil-
           ter (a name that has caused some confusion as to its mean-
           ing in the past) has been renamed to  result_format.   For
           backwards  compatibility  with  the  pre  2.2 LDAP client,
           result_filter can for now be used instead  of  result_for-
           mat,  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.

    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.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 tim-
                  ing 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 param-
                         eter (previously  called  result_filter  see
                         the  COMPATIBILITY  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 speci-
                         fied 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 '%' expan-
                  sions:

                  %%     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 param-
                         eter   identically   to   their   lower-case
                         counter-parts. With the result_format param-
                         eter (previously  called  result_filter  see
                         the  COMPATIBILITY  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  speci-
                         fied  patterns, the saerch is suppressed and
                         returns no results.

                         The above %1, ..., %9 expansions are  avail-
                         able 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_fil-
                         ter,  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 expan-
                         sions 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
                  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.

                  This feature is available in Postfix 1.0 and later.

           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 search 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  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 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 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)