Recommendations on Using Assigned Transport Port Numbers
RFC 7605

Document Type RFC - Best Current Practice (August 2015; Errata)
Last updated 2015-08-21
Replaces draft-touch-tsvwg-port-use
Stream IETF
Formats plain text pdf html
Stream WG state Submitted to IESG for Publication Dec 2014
Consensus Yes
Document shepherd Gorry Fairhurst
Shepherd write-up Show (last changed 2015-01-19)
IESG IESG state RFC 7605 (Best Current Practice)
Telechat date
Responsible AD Spencer Dawkins
Send notices to tsvwg-chairs@ietf.org, draft-ietf-tsvwg-port-use@ietf.org
IANA IANA review state Version Changed - Review Needed
IANA action state No IC
Internet Engineering Task Force (IETF)                          J. Touch
Request for Comments: 7605                                       USC/ISI
BCP: 165                                                     August 2015
Category: Best Current Practice
ISSN: 2070-1721

        Recommendations on Using Assigned Transport Port Numbers

Abstract

   This document provides recommendations to designers of application
   and service protocols on how to use the transport protocol port
   number space and when to request a port assignment from IANA.  It
   provides designer guidance to requesters or users of port numbers on
   how to interact with IANA using the processes defined in RFC 6335;
   thus, this document complements (but does not update) that document.
   It provides guidelines for designers regarding how to interact with
   the IANA processes defined in RFC 6335, thus serving to complement
   (but not update) that document.

Status of This Memo

   This memo documents an Internet Best Current Practice.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   BCPs is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7605.

Touch                     Best Current Practice                 [Page 1]
RFC 7605         Recommendations for Transport Port Use      August 2015

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
   2. Conventions Used in This Document ...............................3
   3. History .........................................................3
   4. Current Port Number Use .........................................5
   5. What is a Port Number? ..........................................5
   6. Conservation ....................................................7
      6.1. Guiding Principles .........................................7
      6.2. Firewall and NAT Considerations ............................8
   7. Considerations for Requesting Port Number Assignments ...........9
      7.1. Is a port number assignment necessary? .....................9
      7.2. How many assigned port numbers are necessary? .............11
      7.3. Picking an Assigned Port Number ...........................12
      7.4. Support for Security ......................................13
      7.5. Support for Future Versions ...............................14
      7.6. Transport Protocols .......................................14
      7.7. When to Request an Assignment .............................16
      7.8. Squatting .................................................17
      7.9. Other Considerations ......................................18
   8. Security Considerations ........................................18
   9. IANA Considerations ............................................19
   10. References ....................................................19
      10.1. Normative References .....................................19
      10.2. Informative References ...................................20
   Acknowledgments ...................................................24
   Author's Address ..................................................24

Touch                     Best Current Practice                 [Page 2]
RFC 7605         Recommendations for Transport Port Use      August 2015

1.  Introduction

   This document provides information and advice to application and
   service designers on the use of assigned transport port numbers.  It
   provides a detailed historical background of the evolution of
   transport port numbers and their multiple meanings.  It also provides
   specific recommendations to designers on how to use assigned port

   numbers.  Note that this document provides information to potential
Show full document text