|TCPMUX, TCP Port Service Multiplexer|
|Protocol type:||Application layer protocol.|
A TCP client connects to a foreign host on TCP port 1. It sends the service name followed by a carriage-return line-feed <CRLF>. The service name is never case sensitive. The server replies with a single character indicating positive ("+") or negative ("-") acknowledgment, immediately followed by an optional message of explanation, terminated with a <CRLF>. If the reply was positive, the selected protocol begins; otherwise the connection is closed.
The name "HELP" is reserved. If received, the server will output a multi-line message and then close the connection. The reply to the name "HELP" must be a list of the service names of the supported services, one name per line.
|MAC header||IP header||TCP header||TCPMUX message||Data :::|
[RFC 1078] TCP Port Service Multiplexer (TCPMUX).