proxymap(8) - NetBSD Manual Pages

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PROXYMAP(8)                                                        PROXYMAP(8)




NAME

       proxymap - Postfix lookup table proxy server


SYNOPSIS

       proxymap [generic Postfix daemon options]


DESCRIPTION

       The  proxymap server provides read-only table lookup service to Postfix
       processes. The purpose of the service 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
              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 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.

       The proxymap 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).

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

       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 servers run under control by the Postfix master server.   Each
       server  can handle multiple simultaneous connections.  When all servers
       are busy while a client connects, the master  creates  a  new  proxymap
       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  server  opens  only  tables  that  are  approved via the
       proxy_read_maps configuration parameter, 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  server  is not a trusted daemon process, and must not be
       used to look up sensitive information such as user or group IDs,  mail-
       box file/directory names or external commands.


DIAGNOSTICS

       Problems and transactions are logged to syslogd(8).


BUGS

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


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 con-
              figuration files.

       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 the next service request before exiting.

       max_use (100)
              The  maximal number of connection requests before a Postfix dae-
              mon process terminates.

       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.


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)