TCP_TABLE(5) File Formats Manual 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
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.
Each request specifies a command, a lookup key, and possibly a lookup
get SPACE key NEWLINE
Look up data under the specified key.
put SPACE key SPACE value NEWLINE
This request is currently not implemented.
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.
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
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
Use "postconf readme_directory" or "postconf html_directory" to locate
DATABASE_README, Postfix lookup table overview
The Secure Mailer license must be distributed with this software.
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA