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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. Alternatively, table lookups can be directed
       to a TCP server.

       To find out what types of lookup tables your Postfix  sys-
       tem 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 possi-
       bly 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 hexadecimal 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  pur-
       poses.   The client-server connection is not protected and
       the server is not authenticated.

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
       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

                                                                  TCP_TABLE(5)