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 search 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/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  direc-
                  tory entries returned by the lookup, to be resolved
                  to an email address.

                      result_attribute = mailbox, maildrop

           special_result_attribute (default: empty)
                  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 = memberdn

                  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.

           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  expan-
                  sion  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.

                      terminal_result_attribute = 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 expan-
                  sion  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

                  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  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.  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 con-
                  figuration files.

                  The "try" and "never" 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.exam-
           ple.com.   It will bind anonymously, search for any direc-
           tory 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 deliv-
           ered.

    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)