Provided by: postfix_2.11.0-1ubuntu1.2_amd64 
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 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
TCP_TABLE(5)