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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 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 ver-
              sion 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 purposes.  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
       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



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