Browse Prior Art Database

TCP port service Multiplexer (TCPMUX) (RFC1078) Disclosure Number: IPCOM000001887D
Original Publication Date: 1988-Nov-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 2 page(s) / 3K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

M. Lottor: AUTHOR


Status of this Memo

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 100% of the total text.

Network Working Group M. Lottor

Request For Comments: 1078 SRI-NIC

November 1988

TCP Port Service Multiplexer (TCPMUX)

Status of this Memo

This RFC proposes an Internet standard which can be used by future

TCP services instead of using 'well-known ports'. Distribution of

this memo is unlimited.


Ports are used in the TCP to name the ends of logical connections

which carry long term conversations. For the purpose of providing

services to unknown callers, a service contact port is defined. The

contact port is sometimes called the "well-known port". Standard TCP

services are assigned unique well-known port numbers in the range of

0-255. These ports are of limited number and are typically only

assigned to official Internet protocols.

This RFC defines a protocol to contact multiple services on a single

well-known TCP port using a service name instead of a well-known

number. In addition, private protocols can make use of the service

without needing an official TCP port assignment.

The 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 . 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 . If the reply was positive,

the selected protocol begins; otherwise the connection is closed.

Service Names

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.

The names listed in the "Protocol and Service Names" section of the

current edition of "Assigned Numbers" (RFC-1010 at this time) are

reserved to have exactly the definitions specified there. Services

with distinct assigned ports must be available on those ports and may

optionally be available via this port service multiplexer on port 1.

Private protocols should use a service name that has a high chance of

being unique. A good practice is to prefix the protocol name with

the name of your organization.

Multiple versions of a protocol can suffix the service name with a

protocol version number.

Implementation Notes

A negative reply will typically be returned by the port-multiplexing

process when it can't find the requested service. A positive reply

will typically be returned by the process invoked by the port

multiplexer for the requested service.