TCP_TABLE(5)                                                      TCP_TABLE(5)

NAME
       tcp_table - Postfix client/server table lookup protocol

SYNOPSIS
       postmap -q "string" tcp:host:port

       postmap -q - tcp:host:port <inputfile

DESCRIPTION
       The  Postfix  mail system uses optional tables for address rewriting or
       mail routing. These tables are usually in dbm or  db  format.  Alterna-
       tively, table lookups can be directed to a TCP server.

       To  find  out  what types of lookup tables your Postfix system supports
       use the "postconf -m" command.

       To test lookup tables, use the "postmap -q" command as described in the
       SYNOPSIS above.

PROTOCOL DESCRIPTION
       The TCP map class implements a very simple protocol: the client sends a
       request, and the server sends one reply. Requests and replies are  sent
       as  one  line of ASCII text, terminated by the ASCII newline character.
       Request and reply parameters (see below) are separated by whitespace.

       Send and receive operations must complete in 100 seconds.

REQUEST FORMAT
       Each request specifies a command, a lookup key, and possibly  a  lookup
       result.

       get SPACE key NEWLINE
              Look up data under the specified key.

       put SPACE key SPACE value NEWLINE
              This request is currently not implemented.

REPLY FORMAT
       Each  reply specifies a status code and text. Replies must be no longer
       than 4096 characters including the newline terminator.

       500 SPACE text NEWLINE
              In case of a lookup request, the requested data does not  exist.
              In  case  of  an  update request, the request was rejected.  The
              text describes the nature of the problem.

       400 SPACE text NEWLINE
              This indicates an error condition. The text describes the nature
              of the problem. The client should retry the request later.

       200 SPACE text NEWLINE
              The request was successful. In the case of a lookup request, the
              text contains an encoded version of the requested data.

ENCODING
       In request and reply parameters, the  character  %,  each  non-printing
       character, and each whitespace character must be replaced by %XX, where
       XX is the corresponding ASCII hexadecimal character value. The hexadec-
       imal codes can be specified in any case (upper, lower, mixed).

       The  Postfix  client always encodes a request.  The server may omit the
       encoding as long as the reply is guaranteed to not  contain  the  %  or
       NEWLINE character.

SECURITY
       Do  not  use  TCP  lookup  tables  for security critical purposes.  The
       client-server connection is not protected and the server is not authen-
       ticated.

BUGS
       Only the lookup method is currently implemented.

       The  client  does  not  hang  up when the connection is idle for a long
       time.

SEE ALSO
       postmap(1), Postfix lookup table manager
       regexp_table(5), format of regular expression tables
       pcre_table(5), format of PCRE tables
       cidr_table(5), format of CIDR tables

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.

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

                                                                  TCP_TABLE(5)