Postfix manual - proxymap(8)

    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 table lookup
           service to Postfix processes. The purpose of  the  service
           is:

           o      To  overcome  chroot  restrictions.  For example, a
                  chrooted SMTP server needs  access  to  the  system
                  passwd  file  in order to reject mail for non-exis-
                  tent 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

           o      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 connec-
                  tions" 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(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 map-
                  type dependent flags (to distinguish a fixed string
                  table from a regular expression table).

           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  map-
                  type: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(8) servers run under control by the Postfix  mas-
           ter(8) server.  Each server can handle multiple simultane-
           ous 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 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(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 rec-
           ognizes  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-sen-
           sitive processes.

    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.

    CONFIGURATION PARAMETERS
           On busy mail systems a long time  may  pass  before  prox-
           ymap(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.

           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 daemon 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.

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

    README FILES
           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)