Provided by: postfix_3.4.5-1ubuntu1_amd64 bug

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 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.

       ·      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 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 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  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
       sensitive 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 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 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
              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 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)