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TCP_TABLE(5) File Formats Manual 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



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.






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. 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 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
Wietse Venema
Google, Inc.
111 8th Avenue
New York, NY 10011, USA