Dedicated to preserving the central coordinating functions of the global
Internet for the public good.

Application for User (Registered) Port Number

The User (Registered) Ports are those from 1024 through 49151. (See http://www.iana.org/assignments/port-numbers.)

Because of their limited number, registered ports are a scarce resource, and therefore IANA must examine each application carefully. At the same time, assignment of a port number does not in any way imply an endorsement of an appliction or product, and the fact that network traffic is flowing to or from a registered port does not mean that it is "good" traffic. Firewall and system administrators should choose how to configure their systems based on their knowledge of the traffic in question, and any other relevant criteria.

The IANA needs a technical description on your proposed use of a user port number. We require enough detail to understand how your application uses the network. Once we have the above information in hand, and understand it, we can assign a user port number.

IESG STATEMENT to the IANA

The IESG believes that IANA may allocate an additional port in the 'user port' range to protocols whose current port allocation requires access to a privileged port. This allocation should not be automatic, but may occur upon application by an interested party whose application would otherwise fit IANA's policies.

Please note that a particular application or service should be able to operate only one registered user port number. For applications or services that offer multiple functions it is usually possible to use one port as a multiplexer or rendezvous service. That is, the client always initiates the use of a service by contacting the rendezvous port and indicating in its first message which function is needed. The rendezvous service then either (A) creates (forks, spawns) a process to perform that function and passes the connection to it; or (B) dynamically selects a (high-numbered) port and starts a process to perform the function listening on that port and sends a message back to the client telling it to call the new process on that port.

If you are applying for a DCCP port number, please review the guidelines at the following: Datagram Congestion Control Protocol (DCCP)

Please see below for the application:

We need at least the following information, which is for our internal use only.

  • Your Name:

  • Your E-mail:

  1. What is the protocol-number between the user machine and the server machine?

  2. What message formats are used?
    [The sequence of fields in a message. For example, length, opcode, argument, filename, null.]

  3. What message types are used?
    [The kinds of messages in the protocol. For example, request, reply, cancel, interrupt.]

  4. What message op codes are used?
    [The operation codes in the protocol. For example, read, write, delete, restore.]

  5. What message sequences are used?
    [The allowed sequences of messages. For example, a client sends a request and must wait for a reply from the server, except it can send a cancel.]

  6. What functions are performed by this protocol?

  7. Is either broadcast or multicast used?
    Yes No

    If yes, how and what for?

  8. Please give us a technical description of your proposed use of the user port number. (At least 2 paragraphs)

  9. What is the proposed name of the user port number? (For example: Super User Message Service)

  10. What SHORT name (14 CHARACTER MAXIMUM) do you want associated with this port number? (For example: sums)


(Pressing the submit button will cause your application to be transmitted by email to the IANA staff.)

Please send comments on this web site to: webmaster@iana.org
Page Updated 09-July-2004.
Copyright © 2004 The Internet Corporation for Assigned Names and Numbers. All rights reserved.