TCP_TABLE(5)                                                      TCP_TABLE(5)

       tcp_table - Postfix client/server table lookup protocol

       postmap -q "string" tcp:host:port

       postmap -q - tcp:host:port <inputfile

       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.

       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.

       The tcp_table protocol supports only the lookup request.   The  request
       has the following form:

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

       Postfix  will  not  generate  partial  search keys such as domain names
       without one or more subdomains, network addresses without one  or  more
       least-significant  octets,  or  email  addresses without the localpart,
       address extension or domain portion. This behavior is also  found  with
       cidr:, pcre:, and regexp: tables.

       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.
              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.

       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.

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

       Only the lookup method is currently implemented.

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

       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

       DATABASE_README, Postfix lookup table overview

       The Secure Mailer license must be distributed with this software.

       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