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PROXYMAP(8)                                                                                      PROXYMAP(8)



NAME
       proxymap - Postfix lookup table proxy server

SYNOPSIS
       proxymap [generic Postfix daemon options]

DESCRIPTION
       The  proxymap(8)  server  provides read-only or read-write table lookup service to Postfix processes.
       These services are implemented with distinct service names: proxymap  and  proxywrite,  respectively.
       The purpose of these services is:

       •      To  overcome chroot restrictions. For example, a chrooted SMTP server needs access to the sys-tem system
              tem passwd file in order to reject mail for non-existent local addresses, but it is not  prac-tical practical
              tical to maintain a copy of the passwd file in the chroot jail.  The solution:

              local_recipient_maps =
                  proxy:unix:passwd.byname $alias_maps

       •      To  consolidate the number of open lookup tables by sharing one open table among multiple pro-cesses. processes.
              cesses. For example, making mysql connections from every Postfix  daemon  process  results  in
              "too many connections" errors. The solution:

              virtual_alias_maps =
                  proxy:mysql:/etc/postfix/virtual_alias.cf

              The total number of connections is limited by the number of proxymap server processes.

       •      To  provide single-updater functionality for lookup tables that do not reliably support multi-ple multiple
              ple writers (i.e. all file-based tables).

       The proxymap(8) server implements the following requests:

       open maptype:mapname flags
              Open the table with type maptype and name mapname, as controlled by flags. The reply  includes
              the maptype dependent flags (to distinguish a fixed string table from a regular expression ta-ble). table).
              ble).

       lookup maptype:mapname flags key
              Look up the data stored under the requested key.  The reply is the request  completion  status
              code and the lookup result value.  The maptype:mapname and flags are the same as with the open
              request.

       update maptype:mapname flags key value
              Update the data stored under the requested key.  The reply is the  request  completion  status
              code.  The maptype:mapname and flags are the same as with the open request.

              To implement single-updater maps, specify a process limit of 1 in the master.cf file entry for
              the proxywrite service.

              This request is supported in Postfix 2.5 and later.

       delete maptype:mapname flags key
              Delete the data stored under the requested key.  The reply is the  request  completion  status
              code.  The maptype:mapname and flags are the same as with the open request.

              This request is supported in Postfix 2.5 and later.

       sequence maptype:mapname flags function
              Iterate   over   the  specified  database.  The  function  is  one  of  DICT_SEQ_FUN_FIRST  or
              DICT_SEQ_FUN_NEXT.  The reply is the request completion status  code  and  a  lookup  key  and
              result value, if found.

              This request is supported in Postfix 2.9 and later.

       The  request  completion  status  is  one  of OK, RETRY, NOKEY (lookup failed because the key was not
       found), BAD (malformed request) or DENY (the table is not approved for proxy read or update  access).

       There is no close command, nor are tables implicitly closed when a client disconnects. The purpose is
       to share tables among multiple client processes.

SERVER PROCESS MANAGEMENT
       proxymap(8) servers run under control by the Postfix master(8) server.  Each server can handle multi-ple multiple
       ple  simultaneous connections.  When all servers are busy while a client connects, the master(8) cre-ates creates
       ates a new proxymap(8) server process, provided that the process limit is not exceeded.  Each  server
       terminates after serving at least $max_use clients or after $max_idle seconds of idle time.

SECURITY
       The   proxymap(8)   server   opens   only  tables  that  are  approved  via  the  proxy_read_maps  or
       proxy_write_maps configuration parameters, does not talk to users, and can run at  fixed  low  privi-lege, privilege,
       lege,  chrooted  or  not.   However,  running the proxymap server chrooted severely limits usability,
       because it can open only chrooted tables.

       The proxymap(8) server is not a trusted daemon process, and must not be used  to  look  up  sensitive
       information such as user or group IDs, mailbox file/directory names or external commands.

       In Postfix version 2.2 and later, the proxymap client recognizes requests to access a table for secu-rity-sensitive security-sensitive
       rity-sensitive purposes, and opens the table directly. This allows the same  main.cf  setting  to  be
       used by sensitive and non-sensitive processes.

       Postfix-writable data files should be stored under a dedicated directory that is writable only by the
       Postfix mail system, such as the Postfix-owned data_directory.

       In particular, Postfix-writable files should never exist in root-owned directories. That  would  open
       up  a  particular  type  of  security  hole where ownership of a file or directory does not match the
       provider of its content.

DIAGNOSTICS
       Problems and transactions are logged to syslogd(8).

BUGS
       The proxymap(8) server provides service to multiple clients, and  must  therefore  not  be  used  for
       tables that have high-latency lookups.

       The  proxymap(8)  read-write  service  does  not explicitly close lookup tables (even if it did, this
       could not be relied on, because the process may be terminated between table updates).  The read-write
       service  should  therefore  not  be used with tables that leave persistent storage in an inconsistent
       state between updates (for example, CDB). Tables that support "sync on update" should  be  safe  (for
       example, Berkeley DB) as should tables that are implemented by a real DBMS.

CONFIGURATION PARAMETERS
       On  busy  mail systems a long time may pass before proxymap(8) relevant changes to main.cf are picked
       up. Use the command "postfix reload" to speed up a change.

       The text below provides only a parameter summary. See postconf(5) for more  details  including  exam-ples. examples.
       ples.

       config_directory (see 'postconf -d' output)
              The default location of the Postfix main.cf and master.cf configuration files.

       data_directory (see 'postconf -d' output)
              The directory with Postfix-writable data files (for example: caches, pseudo-random numbers).

       daemon_timeout (18000s)
              How much time a Postfix daemon process may take to handle a request before it is terminated by
              a built-in watchdog timer.

       ipc_timeout (3600s)
              The time limit for sending or receiving information over an internal communication channel.

       max_idle (100s)
              The maximum amount of time that an idle Postfix daemon process waits for an  incoming  connec-tion connection
              tion before terminating voluntarily.

       max_use (100)
              The  maximal  number of incoming connections that a Postfix daemon process will service before
              terminating voluntarily.

       process_id (read-only)
              The process ID of a Postfix command or daemon process.

       process_name (read-only)
              The process name of a Postfix command or daemon process.

       proxy_read_maps (see 'postconf -d' output)
              The lookup tables that the proxymap(8) server is allowed to access for the read-only  service.

       Available in Postfix 2.5 and later:

       data_directory (see 'postconf -d' output)
              The directory with Postfix-writable data files (for example: caches, pseudo-random numbers).

       proxy_write_maps (see 'postconf -d' output)
              The lookup tables that the proxymap(8) server is allowed to access for the read-write service.

SEE ALSO
       postconf(5), configuration parameters
       master(5), generic daemon options

README FILES
       Use "postconf readme_directory" or "postconf html_directory" to locate this information.
       DATABASE_README, Postfix lookup table overview

LICENSE
       The Secure Mailer license must be distributed with this software.

HISTORY
       The proxymap service was introduced with Postfix 2.0.

AUTHOR(S)
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA



                                                                                                 PROXYMAP(8)