phpman > man > proxymap(8postfix)

PROXYMAP(8postfix)                                                                PROXYMAP(8postfix)



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 pro‐
       cesses. 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 system passwd file in order to reject mail for non-existent local  addresses,  but
              it is not practical to maintain a copy of the passwd file in the chroot jail.  The so‐
              lution:

              local_recipient_maps =
                  proxy:unix:passwd.byname $alias_maps

       •      To consolidate the number of open lookup tables by sharing one open table among multi‐
              ple processes. 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
              multiple 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 regu‐
              lar expression table).

       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 up‐
       date 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 han‐
       dle multiple simultaneous connections.  When all servers are busy while  a  client  connects,
       the  master(8)  creates  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
       privilege,  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  sen‐
       sitive  information  such as UNIX 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  security-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) or postlogd(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 up‐
       date" 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
       examples.

       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  ter‐
              minated 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
              connection 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.

       Available in Postfix 3.3 and later:

       service_name (read-only)
              The master.cf service name of a Postfix daemon process.

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

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA



                                                                                  PROXYMAP(8postfix)