Transport Area Working Group                                  M. Cotton
Internet Draft                                                    ICANN
Updates: 2780, 4340 (if approved)                             L. Eggert
Intended status: BCP                                              Nokia
Expires: May 2009                                             A. Mankin
                                                    Johns Hopkins Univ.
                                                          M. Westerlund
                                                               J. Touch
                                                       November 3, 2008

       IANA Procedures for the Transport Protocol Port Number Space

Status of this Memo

   By submitting this Internet-Draft, each author represents that
   any applicable patent or other IPR claims of which he or she is
   aware have been or will be disclosed, and any of which he or she
   becomes aware will be disclosed, in accordance with Section 6 of
   BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   The list of current Internet-Drafts can be accessed at

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   This Internet-Draft will expire on May 3, 2009.


   This document defines the IANA procedures for registering port number
   values for use with the various IETF transport protocols, including

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   TCP, UDP, DCCP, and SCTP.  It provides clear procedures for the
   management of the port number registry, which is important for its
   long-term management.  It updates RFC2780 by obsoleting Sections 8
   and 9.1 of that RFC, and it updates the IANA allocation procedures
   for DCCP as defined in RFC4340.

Table of Contents

   1. Introduction...................................................2
   2. Conventions used in this document..............................4
   3. Port Number Types..............................................5
      3.1. Assigned Port Numbers for Experimentation.................5
   4. Principles for Port Number Space Management....................6
      4.1. Basic Principles of Port Conservation.....................7
      4.2. Principles Specific to Individual Port Number Ranges......8
      4.3. New Principles............................................9
   5. IANA Procedures for Managing the Port Number Space............10
      5.1. Port Number Registration.................................10
      5.2. Port Number De-Registration..............................12
      5.3. Port Number Re-Use.......................................12
      5.4. Port Number Revocation...................................12
      5.5. Port Number Transfer.....................................13
      5.6. Maintenance Issues.......................................13
   6. Port Number Space Requests....................................13
      6.1. Request Procedure........................................13
   7. Security Considerations.......................................14
   8. IANA Considerations...........................................14
   9. Acknowledgments...............................................15
   10. References...................................................16
      10.1. Normative References....................................16
      10.2. Informative References..................................16
   APPENDIX A: Updates to DCCP Registries...........................19
      A.1. DCCP Service Code Registry...............................19
      A.1. DCCP Port Numbers Registry.....Error! Bookmark not defined.

1. Introduction

   The Transmission Control Protocol (TCP) [RFC0793] and the User
   Datagram Protocol (UDP) [RFC0768] have enjoyed a remarkable success
   over the decades as the two most widely used transport protocols on
   the Internet.  They have introduced the concept of "ports" as logical
   entities for Internet communication.  Ports serve two purposes:
   first, they provide a demultiplexing identifier to differentiate
   transport sessions between the same pair of endpoints, and second,
   they also identify the application protocol and associated service to
   which processes bind [I-D.touch-tsvwg-port-guidelines].  Newer

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   transport protocols, such as the Stream Control Transmission Protocol
   (SCTP) [RFC4960] and the Datagram Congestion Control Protocol (DCCP)
   [RFC4342] have adopted the concept of ports for their communication
   sessions and use port numbers in the same way as TCP and UDP.

   Port numbers are the original and most widely used means for
   application and service identification on the Internet.  Ports are
   16-bit numbers, and the combination of source and destination port
   numbers together with the IP addresses of the communicating end
   systems uniquely identifies a session of a given transport protocol.
   Port numbers are also known by their corresponding service names such
   as "telnet" for port number 23 and "http" for port number 80.

   Hosts running services, hosts accessing services on other hosts, and
   intermediate devices (such as firewalls and NATs) that restrict
   services need to agree on which service corresponds to a particular
   destination port.  Although this can be a local decision between the
   endpoints of a connection, most Internet components use a single,
   shared view of this association, provided by the Internet Assigned
   Numbers Authority (IANA) through the port number registry [REGISTRY].

   Designers of applications and application-level protocols may apply
   to IANA for a registered port number for a specific application, and
   may - after successful registration - assume that no other
   application will use that service port number for its communication
   sessions. It is important to note that ownership of registered port
   numbers remains with IANA.  For many years, the allocation and
   registration of new port number values for use with TCP and UDP have
   had less than clear guidelines.  Information about the registration
   procedures for the port namespace existed in three locations: the
   forms for requesting port number registrations on the IANA web site
   [SYSFORM][USRFORM], an introductory text section in the file listing
   the port number registrations themselves [REGISTRY], and two brief
   sections of [RFC2780].

   This document aggregates this scattered information into a single
   reference and at the same time clarifies the guidelines for the
   management of the port number space.  It gives more detailed guidance
   to prospective requesters of ports than the existing documentation,
   and it streamlines the IANA procedures for the management of the port
   number space, so that management requests can complete in a timely
   manner.  A key factor of this streamlining is to establish identical
   registration procedures for transport protocol ports, independent of
   a specific transport protocol.  This document brings the IANA
   procedures for TCP and UDP in line with those already in effect for
   SCTP and DCCP, resulting in a single process that requesters and IANA

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   follow for all port number requests for all transport protocols,
   including those not yet defined.

   A second purpose of this document is to describe the principles that
   guide the IETF and IANA in their role as the long-term joint stewards
   of the port number space.  TCP and UDP have been a remarkable success
   over the last decades.  Thousands of applications and application-
   level protocols have registered ports for their use, and there is
   every reason to believe that this trend will continue into the
   future.  It is hence extremely important that management of the port
   number space follow principles that ensure its long-term usefulness
   as a shared resource.  Section 4 discusses these principles in
   detail.  Guidelines for users seeking port numbers, as well as a
   detailed history of the port number registry and alternate means for
   coordinating host agreement on service-to-port-number mappings, is
   provided in a companion document [I-D.touch-tsvwg-port-guidelines].

   In addition to detailing the IANA procedures for the initial
   assignment of port numbers, this document also specifies post-
   assignment procedures that until now have been handled in an ad hoc
   manner.  These include procedures to de-register a port number that
   is no longer in use, to re-use a port number allocated for one
   application that is no longer in use for another application, and
   procedure by which IANA can unilaterally revoke a prior port number
   registration.  Section 5 discusses the specifics of these procedures.

   This document also addresses two technical issues related to the
   ports registry that are tangential to long-term stewardship.  First,
   it clarifies that a method for the early allocation of port numbers
   is available for IETF working groups, in line with [RFC4020].
   Second, it discusses how the use of symbolic names for assigned ports
   (the "keyword" field in [REGISTRY]) for Service Resource Records (SRV
   RRs) in the Domain Name System (DNS) [RFC2782] relates to the use of
   SRV RRs for applications without an assigned port.

   This document updates [RFC2780] by obsoleting Sections 8 and 9.1 of
   RFC.  Note that [RFC5237] updates a different subset of the IANA
   allocation guidelines originally given in [RFC2780] (specifically,
   the policies on the namespace of the IP protocol number and IPv6 next

2. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC-2119 [RFC2119].

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3. Port Number Types

   TCP, UDP (and UDP-Lite), SCTP and DCCP use 16-bit namespaces for
   their port number registries.  The port registries for all these
   transport protocols are subdivided into three ranges of numbers, and
   Section 6 describes the IANA procedures for each range in detail:

   o  the Well Known Ports, i.e., the System Ports, from 0-1023
      (assigned by IANA)

   o  the Registered Ports, i.e., the User Ports, from 1024-49151
      (assigned by IANA)

   o  the Dynamic Ports, i.e., the Private Ports, from 49152-65535
      (never assigned)

   Of the assignable port ranges (Well Known and Registered, i.e., port
   numbers 0-49151), individual port numbers are in one of three states
   at any given time:

   1. Assigned: Assigned port numbers are currently allocated to the
      service indicated in the registry.

   2. Unassigned: Unassigned port numbers are currently available for
      assignment upon request, as per the procedures outlined in this

   3. Reserved: Reserved port numbers are not available for regular
      assignment; they are "assigned to IANA" for special purposes.
      Reserved port numbers include values at the edges of each range,
      e.g., 0, 1023, 1024, etc., which may be used to extend these
      ranges or the overall port number space in the future.

   When this document was written, approximately 76% of the TCP and UDP
   Well Known Ports were assigned, as were a significant fraction of the
   Registered Ports.  (As noted, Dynamic Ports are never assigned.)

3.1. Assigned Port Numbers for Experimentation

   Of the Well-Known Ports, two TCP and UDP port numbers (1021 and 1022)
   have been assigned for experimentation with new applications and
   application-layer protocols that require a port number in the
   assigned ports ranges [RFC4727]. [sctp-dccp-exp]

   The experimental ports 1021 and 1022 SHOULD be used for local
   experiments only in controlled environments, and they SHOULD NOT be
   used on the global Internet.  Many new applications and application-

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   layer protocols can be experimented with without requiring a port in
   the Well-Known or Registered Ports range, and port numbers in the
   Dynamic Ports range can be also used.

   Unfortunately, it can be difficult to limit access to these ports.
   Users SHOULD take measures to ensure that experimental ports are
   connecting to the intended process.  For example, users of these
   experimental ports might include a 64-bit nonce, once on each segment
   of a message-oriented channel (e.g., UDP), or once at the beginning
   of a byte-stream (e.g., TCP), which is used to confirm that the port
   is being used as intended.  Such confirmation of intended use is
   especially important when these ports are associated with privileged
   (e.g., system or administrator) processes.

4. Principles for Port Number Space Management

   Management procedures for the port number space include allocation of
   port numbers upon request, as well as coordination of information
   about existing allocations.  The latter includes maintaining contact
   and description information about assigned ports, revoking abandoned
   ports, and redefining port allocations when needed.  Of these
   procedures, port number allocation is most critical, because of the
   limited number of remaining port numbers.

   Before the publication of this document, the principles of port
   number space allocation followed some simple, undocumented

   o  TCP and UDP ports were simultaneously allocated when either was

   o  Port numbers were the primary allocation; service names were
      informative only, and did not need to be unique

   o  Port numbers were conserved informally, and sometimes
      inconsistently (e.g., some services were allocated ranges of many
      port numbers even where not strictly necessary)

   o  SCTP and DCCP port number and service name spaces were managed
      separately from the TCP/UDP spaces

   This document attempts to update these guidelines to more
   conservatively manage the limited remaining TCP and UDP port number
   spaces, recognizes the potential use of service names in the absence
   of corresponding port number allocations, such as in SCTP and DCCP.

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   The basic principle of port number registry management is to conserve
   the space where possible.  Extensions to support larger port number
   spaces would require changing many core protocols of the current
   Internet in a way that would not be backward compatible and interfere
   with both current and legacy applications.

   Port numbers are intended to indicate a service and enable process
   demultiplexing at an endpoint; uses beyond those basic requirements
   should be avoided [I-D.touch-tsvwg-port-guidelines].  This document
   also focuses on service names as a unique identifier, to increase the
   space available (from 4 bytes to 14), and to enable their use in the
   absence of corresponding port number assignments.

4.1. Basic Principles of Port Conservation

   This section summarizes the basic principles by which IANA attempts
   to conserve the port number space.  This description is intended to
   inform applicants requesting port numbers.  IANA decisions are not
   required to be bound to these principles, however; other factors may
   come into play, and exceptions may occur where deemed in the best
   interest of the Internet.

   Conservation of the port number space recognizes that because this
   space is a limited resource, applications are expected to participate
   in the demultiplexing process where feasible.  The port numbers are
   expected to encode as little information as possible that will enable
   an application to perform further multiplexing by itself.  In
   particular, there should be:

   o  only one port per service

   o  one port for all versions of a service

   o  the same port for different types of devices using the same


   A given service is expected to further demultiplex messages where
   possible.  For example, applications and protocols are expected to
   include in-band version information, so that future versions of the
   application or protocol can share the same allocated port.

   Applications and protocols are also expected to be able to
   efficiently use a single allocated port, either by demultiplexing
   multiple streams within one port, or using the allocated port to
   coordinate using dynamic ports for subsequent exchanges (e.g., in the
   spirit of FTP [RFC0959]).

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   These principles of port conservation are explained in [I-D.touch-
   tsvwg-port-guidelines].  That document explains in further detail how
   ports are used in various ways, notably:

   o  Endpoint process identifier

   o  Application protocol identifier

   o  Firewall filtering

   The process and protocol identifier use suggests that anything a
   single process can demultiplex, or that can be encoded into a single
   protocol, should be.  The firewall filtering use suggests that some
   uses that could be de-multiplexed or encoded must be separated to
   allow for firewall management.  Note that this latter use is much
   less sound, because port numbers have meaning only for the two
   endpoints of a connection (again, as discussed in detail in [I-

4.2. Principles Specific to Individual Port Number Ranges

   It is important to note that different IANA procedures apply to
   different ranges of the port number registry.  Section 6 discusses
   the details of these procedures; this section outlines the rationale
   for these differences:

   o  Ports in the Dynamic Ports range (49152-65535) have been
      specifically set aside for local and dynamic use and cannot be
      registered through IANA.  Applications may simply use them for
      communication without any sort of registration.  On the other
      hand, applications MUST NOT assume that a specific port number in
      the Dynamic Ports range will always be available for communication
      at all times, and a port number in that range hence MUST NOT be
      used as a service identifier.

   o  Ports in the Registered Ports range (1024-49151) are available for
      registration through IANA, and MAY be used as service identifiers
      upon successful registration.  Because registering a port number
      for a specific application consumes a fraction of the shared
      resource that is the port number registry, IANA will require the
      requester to document the intended use of the port number, and
      have a technical expert review this documentation to determine
      whether to grant the registration request.  This documentation
      MUST explain why a port number in the Dynamic Ports range is
      unsuitable for the given application.

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   o  Ports in the Well Known Ports range (0-1023) are also available
      for registration through IANA.  Because the Well Known Ports range
      is both the smallest and the most densely allocated one, the bar
      for new allocations is higher than that for the Registered Ports
      range (1024-49551).  A request for a Well Known port number MUST
      document why a port number in the Registered Ports or Dynamic
      Ports ranges is unsuitable.

4.3. New Principles

   Several new practices stem from the conservation principle that
   guides management of the port numbers registry, and will take effect
   with the approval of this document:

   o  IANA will allocate port numbers only to the transport protocols

   o  IANA will recover unused port numbers, via the new procedures of
      de-registration, revocation, and transfer

   IANA will begin assigning protocol numbers only for those transport
   protocols explicitly included in a registration request.  This ends
   the long-standing practice of automatically assigning a port number
   to an application for both TCP and a UDP, even if the request is only
   for one of these transport protocols.  The new allocation procedure
   conserves resources by only allocating a port number to an
   application for those transport protocols (TCP, UDP, SCTP and/or
   DCCP) it actually uses.  The port number will be marked as reserved -
   instead of assigned - in the port number registries of the other
   transport protocols.  When applications start supporting the use of
   some of those additional transport protocols, they must request IANA
   to convert the reservation into an assignment.  An application MUST
   NOT assume that it can use a port number assigned to it for use with
   one transport protocol with another transport protocol without
   another registration with IANA.  The reason for this procedure is to
   allow allocation of reserved port numbers on the day the range has no
   more unassigend values. [port-reserv]

   Conservation for the port numbers registry is improved by procedures
   that allow previously allocated port numbers to become unassigned,
   either through de-registration or through revocation, and by a
   procedure that lets application designers transfer an allocated but
   unused port number to a new application.  Section 5 describes these
   procedures, which so far were undocumented.

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5. IANA Procedures for Managing the Port Number Space

   IANA supports various procedures to manage the port number space that
   enable ports to be registered, de-registered, reused, and revoked.
   This section explains these procedures, as well as other related

5.1. Port Number Registration

   Registration refers to the allocation of port numbers to applicants.
   All such registrations are made from port numbers that are Unassigned
   or Reserved at the time of the allocation.  Unassigned numbers are
   allocated as needed, and without further explanation.  Reserved
   numbers are assigned only after review by IANA and the IETF, and are
   accompanied by a statement explaining the reason a reserved number is
   appropriate for this action.

   When a registration for one or more (but not all) transport protocols
   is approved, the port number for the non-requested transport
   protocol(s) will remain unassigned but is marked as reserved.
   However, IANA SHOULD NOT assign that port number to any other
   application or service until no port numbers remain unassigned in the
   request range.  The current registration owner of a port number MAY
   register the same port number for other transport protocols when

   A port number registration consists of the following tuple:

   o  Registration Technical Contact:  Name and email address of the
      technical contact person for the registration.  This is REQUIRED.
      Additional address information MAY be provided.  For registrations
      done through IETF-published RFCs, one or more technical contact
      persons SHALL be provided.

   o  Registration Owner: Name and email address of the owner of the
      registration. This is REQUIRED. For individuals, this is the same
      as the registration technical contact; for organizations, this is
      a point of contact at that organization. For registrations done
      through IETF-published RFCs, the registration ownership will
      belong to the IETF and not the technical contact persons.

   o  Transport Protocol:  The transport protocol(s) for which the port
      allocation is requested, currently limited to one or more of TCP,
      UDP, SCTP, and DCCP.

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   o  Port Number:  The currently unassigned port number(s) the
      requester suggests for allocation.  If specified and when
      possible, IANA is encouraged to allocate the suggested number.  If
      not specified, IANA will choose a suitable number from the
      Registered Ports range. Note that the applicant MUST NOT use the
      suggested ports prior to the completion of registration.

   o  Broadcast, Multicast or Anycast:  Indicates whether the protocol
      supports either broadcast, multicast, or anycast network layer

   o  Port Name:  The long name (description) of the port.  It should
      avoid all but the most well known acronyms.

   o  Service Name:  This short name for the port number, used in
      various service selection and discovery mechanisms, currently
      including TCPMUX [RFC1078] and DNS SRV resource records [RFC2782].
      This name is limited to 14 bytes, case-insensitive US-ASCII
      letters, digits, and dashes.  It MUST NOT conflict with already
      allocated names in the service name registry [serv-nam-reg].

   o  Reference:  A reference document describing the protocol or
      application using this port.  For registration requests for
      Registered Ports, this documentation MUST explain why a port
      number in the Dynamic Ports range is unsuitable for the given
      application.  For registration requests for Well Known Ports, this
      documentation MUST explain why a port number in the Registered
      Ports or Dynamic Ports ranges is unsuitable.

   The following rules apply to the port number registry database
   maintained by IANA: [database-rules]

   o  Service Names MUST be unique.

   o  Service Name MUST exist for all transport protocols.

   o  Port Number MUST exist for TCP and UDP; it MAY exist for SCTP and

   o  Transport Protocol MUST exist for all entries.

   o  Service Code MUST NOT occur for TCP, UDP or SCTP, and MUST occur
      for DCCP.

   o  Port Name MUST exist for all entries.

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   o  Currently valid Registration Contact SHOULD exist for all entries;
      it MUST exist for all new entries.

   o  Reference SHOULD exist for all entries.

5.2. Port Number De-Registration

   The original requesters of a granted port number assignment can
   return the port number to IANA at any time if they no longer have a
   need for it.  The port number will be de-registered and will be
   marked as reserved [res-vs-unass]. IANA should not re-assign port
   numbers that have been de-registered until all other available port
   numbers in the specific range have been assigned.

   Before proceeding with a de-registration, IANA needs to reasonably
   establish that the port number is no longer in use.

5.3. Port Number Re-Use

   If the original requesters of a granted port number assignment no
   longer have a need for the registered number, but would like to re-
   use it for a different application, they can submit a request to IANA
   to do so.

   Logically, port number re-use is to be thought of as a de-
   registration followed by an immediate re-registration of the same
   port number for a new application.  Consequently, the information
   that needs to be provided about the proposed new use of the port
   number is identical to what would need to be provided for a new port
   number allocation for the specific ports range.

   IANA needs to carefully review such requests before approving them.
   In some instances, the Expert Reviewer will determine that the
   application that the port number was assigned to has found usage
   beyond the original requester, or that there is a concern that it may
   have such users.  This determination MUST be made quickly.  A
   community call concerning revocation of a port number (see below) MAY
   be considered, if a broader use of the port number is suspected.

5.4. Port Number Revocation

   Sometimes, it will be clear that a specific port number is no longer
   in use and that IANA can de-register it and mark it as reserved [res-
   vs-unass2]. At other times, it may be unclear whether a given
   assigned port number is still in use somewhere in the Internet.  In
   those cases, despite the requester's wish to de-register, IANA must
   consider the consequences that de-registering the port number.

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   With the help of their IESG-appointed Expert Reviewer, IANA SHALL
   formulate a request to the IESG to issue a four-week community call
   concerning the pending port number revocation.  The IESG and IANA,
   with the Expert Reviewer's support, SHALL determine promptly after
   the end of the community call whether revocation should proceed and
   then communicate their decision to the community.  This procedure
   typically involves similar steps to de-registration except that it is
   initiated by IANA.

5.5. Port Number Transfer

   The value of port numbers is defined by their careful management as a
   shared Internet resource, whereas enabling transfer allows the
   potential for associated monetary exchanges to motivate this
   management.  As a result, current IANA procedures do not permit port
   number assignments to be transferred between parties, even when they
   are mutually consenting.  The appropriate alternate procedure is for
   the new party to request its own port number registration and for the
   previous party to release its registration via the de-registration
   procedure outlined above.

5.6. Maintenance Issues

   The previous procedures help IANA manage defining properties of the
   port name space.  There are additional procedures which are
   administrative, and help IANA maintain non-defining information in a
   registration.  This includes changes to the Port Name (i.e.,
   description), and changes to contact information.  These changes are
   coordinated by IANA in an informal manner, and may be initiated by
   either the registrant or by IANA, e.g., the latter when requesting an
   update to current contact information.

6. Port Number Space Requests

   This section describes the process for requests associated with
   IANA's management of the the port number space.  Such requests
   include initial registration, de-registration, re-use, changes to the
   service name, as well as updates to the contact information or port
   name (description).  Revocation is initiated by IANA.

6.1. Request Procedure

All registration requests for a TCP, SCTP, DCCP and/or UDP ports must
contain the following pieces of information:

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   o  Port number tuple:  A port number tuple, as described in Section
      5.1. The port number would typically be omitted; when provided, it
      indicates a preference for requesting a currently unassigned

   o  Port Range:  Indicates the port range desired (i.e., Well Known
      Ports or Registered Ports).

   o  Requested Action:  One of REGISTER, DEREGISTER, REUSE,
      SVC_NAME_CHANGE, or UPDATE_INFO (port name, registration contact).

   The Well Known Ports are assigned by IANA and cover the range 0-1023.
   On many systems, they can only be used by system (or root) processes
   or by programs executed by privileged users.  Registration requests
   for a Well Known port number MUST follow the "IETF Review" policy of
   [RFC5226].  Registrations for a port number in this range MUST
   document why a port number in the Registered Ports range will not
   fulfill the application needs.

   The Registered Ports are assigned by IANA and on most systems can be
   used by ordinary user processes or programs executed by ordinary
   users.  The Registered Ports are in the range 1024-49151.
   Registration requests for a Registered Port number MUST follow the
   "Expert Review" policy of [RFC5226].

7. Security Considerations

   The IANA guidelines described in this document do not change the
   security properties of either TCP, SCTP, DCCP or UDP.

   Assignment of a port number does not in any way imply an endorsement
   of an application or product, and the fact that network traffic is
   flowing to or from a registered port number does not mean that it is
   "good" traffic, or even that it is used by the assigned service.
   Firewall and system administrators should choose how to configure
   their systems based on their knowledge of the traffic in question,
   not whether there is a port number registered or not.

8. IANA Considerations

   This document obsoletes Sections 8 and 9.1 of [RFC2780].  Upon
   approval of this document, IANA is requested to adopt the procedures
   described herein.

   IANA should take immediate actions to resolve inconsistencies raised
   by requirements of this document.

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9. Acknowledgments

   The text in Appendix A is based on a suggestion by Tom Phelan.

   Lars Eggert is partly funded by [TRILOGY], a research project
   supported by the European Commission under its Seventh Framework

   This document was prepared using

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10. References

10.1. Normative References

   [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
             August 1980.

   [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC
             793, September 1981.

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2780] Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
             Values In the Internet Protocol and Related Headers", BCP
             37, RFC 2780, March 2000.

   [RFC4020] Kompella, K. and A. Zinin, "Early IANA Allocation of
             Standards Track Code Points", BCP 100, RFC 4020, February

   [RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram Congestion
             Control Protocol (DCCP)", RFC 4340, March 2006.

   [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
             ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006.

   [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
             IANA Considerations Section in RFCs", BCP 26, RFC 5226, May

10.2. Informative References

   [I-D.touch-tsvwg-port-guidelines] Touch, J., "Guidelines for
             Transport Port Use", Work in Progress, Nov. 2008.

   [REGISTRY] Internet Assigned Numbers Authority (IANA), "Port

   [RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol", STD
             9, RFC 959, October 1985.

   [RFC1078] Lottor, M., "TCP port service Multiplexer (TCPMUX)", RFC
             1078, November 1988.

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   [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
             specifying the location of services (DNS SRV)", RFC 2782,
             February 2000.

   [RFC4342] Floyd, S., Kohler, E., and J. Padhye, "Profile for Datagram
             Congestion Control Protocol (DCCP) Congestion Control ID 3:
             TCP-Friendly Rate Control (TFRC)", RFC 4342, March 2006.

   [RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC
             4960, September 2007.

   [RFC5237] Arkko, J. and S. Bradner, "IANA Allocation Guidelines for
             the Protocol Field", BCP 37, RFC 5237, February 2008.

   [SYSFORM] Internet Assigned Numbers Authority (IANA), "Application
             for System (Well Known) Port Number",

   [TRILOGY] "Trilogy Project",

   [USRFORM] Internet Assigned Numbers Authority (IANA), "Application
             for User (Registered) Port Number",

Editorial Comments

   [database-rules] Lars: Some of these rules below allow entries that
   aren't in full alignment with the procedures in this document. I
   assume that is, because the rules attempt to describe the state of
   the IANA database including all existing entries? If so, we should
   make that clearer.

   [port-reserv] Magnus: The usage of for the above reason reserved port
   numbers should probably not have the same rules as the other reserved
   ports. Needs discussion if we should separate this properly. I think
   the IETF consultation part will make it difficult the day one
   registry runs out of unassigned ones.

   [res-vs-unass]    Lars: This used to say "unassigned" instead of
   "reserved". I suggest "reserved", so that IANA has an indication in
   their list that they need to be careful when re-assigning a
   previously de-registered port.

   [res-vs-unass2]   Lars: See [res-vs-unass].

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   [sctp-dccp-exp]   Lars: This document should register ports 1021 and
   1022 for DCCP and SCTP. Joe: and potentially for all new protocols,
   as suggested by Alfred?

   [serv-nam-reg]    Lars: Add citation to the service name registry
   draft, when it exists

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APPENDIX A: Updates to DCCP Registries

   This document updates the IANA allocation procedures for the DCCP
   Port Number and DCCP Service Codes Registries as defined in

A.1. DCCP Service Code Registry

   Service Codes are allocated first-come-first-served according to
   Section 19.8 of [RFC4340].  This document updates Section 19.8 of
   [RFC4340] by extending the guidelines given there in the following

   o  IANA MAY assign new Service Codes without seeking Expert Review
      using their discretion, but SHOULD seek expert review when a
      request seeks an appreciable number of Service Codes (e.g., more
      than five).

   o  IANA should feel free to contact the DCCP Expert Reviewer with
      questions on any registry, regardless of the registry policy, for
      clarification or if there is a problem with a request [RFC4340].

A.2. DCCP Port Numbers Registry

   The DCCP ports registry is defined by [RFC4340] in Section 19.9.
   Allocations in this registry require prior allocation of a Service
   Code.  Not all Service Codes require IANA-registered ports.  This
   document updates Section 19.9 of [RFC4340] by extending the
   guidelines given there in the following way:

   o  IANA should normally assign a value in the range 1024-49151 to a
      DCCP server port.  IANA allocation requests to allocate port
      numbers in the Well Known Ports range (0 through 1023), require
      IETF action prior to allocation by IANA [RFC4340]. Such action
      typically requires confirmation that the protocol indicated is in
      the standards track of the IETF.

   Section 19.9 of [RFC4340] requires each DCCP server port assignment
   to be associated with at least one Service Code value.  This document
   updates [RFC4340] in the following way:

   o  IANA MUST NOT allocate a single Service Code value to more than
      one DCCP server port.

   o  The set of Service Code values associated with a DCCP server port
      should be recorded in the ports registry.

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   o  A request for additional Service Codes to be associated with an
      already allocated Port Number requires Expert Review.  These
      requests will normally be accepted when they originate from the
      contact associated with the port registration.  In other cases,
      these applications will be expected to use an unallocated port,
      when this is available.

   RFC4340] notes that a short port name MUST be associated with each
   DCCP server port that has been registered.  This document requires
   that this name MUST be unique.

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Authors' Addresses

   Michelle Cotton
   Internet Corporation for Assigned Names and Numbers
   4676 Admiralty Way, Suite 330
   Marina del Rey, CA  90292

   Phone: +1 310 823 9358

   Lars Eggert
   Nokia Research Center
   P.O. Box 407
   Nokia Group  00045

   Phone: +358 50 48 24461

   Allison Mankin
   Johns Hopkins Univ.

   Phone: +1 301 728 7199

   Magnus Westerlund
   Torshamsgatan 23
   Stockholm  164 80

   Phone: +46 8 719 0000

   Joe Touch
   4676 Admiralty Way
   Marina del Rey, CA  90292

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   Phone: +1 310 448 9151

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