Service Name and Transport Protocol Port Number Registry

Last Updated
2026-08-17
Expert(s)
TCP/UDP: Joe Touch; Eliot Lear, Kumiko Ono, Wes Eddy, Brian Trammell,
and Michael Scharf
SCTP: Michael Tuexen
DCCP: Eddie Kohler and Yoshifumi Nishida
Reference
[RFC6335]
Note
Service names and port numbers are used to distinguish between different
services that run over transport protocols such as TCP, UDP, DCCP, and
SCTP.

Service names are assigned on a first-come, first-served process, as
documented in [RFC6335].

Port numbers are assigned in various ways, based on three ranges: System
Ports (0-1023), User Ports (1024-49151), and the Dynamic and/or Private
Ports (49152-65535); the different uses of these ranges are described in
[RFC6335]. According to Section 8.1.2 of [RFC6335], System Ports are 
assigned by the "IETF Review" or "IESG Approval" procedures described in 
[RFC8126]. User Ports are assigned by IANA using the "IETF Review" process, 
the "IESG Approval" process, or the "Expert Review" process, as per 
[RFC6335]. Dynamic Ports are not assigned.

The registration procedures for service names and port numbers are
described in [RFC6335].

Assigned ports both System and User ports SHOULD NOT be used without
or prior to IANA registration.

************************************************************************
* PLEASE NOTE THE FOLLOWING:                                           *
*                                                                      *
* 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 DOES NOT MEAN THAT   *
* IT IS "GOOD" TRAFFIC, NOR THAT IT NECESSARILY CORRESPONDS TO 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.                                                   *
************************************************************************

Request an Assignment
  [https://www.iana.org/protocols/apply]

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Service Name Port Number Transport Protocol Description Assignee Contact Registration Date Modification Date Reference Service Code Unauthorized Use Reported Assignment Notes
gdomap 538 tcp gdomap [Richard_Frith_Macdon] [Richard_Frith_Macdon]
gdomap 538 udp gdomap [Richard_Frith_Macdon] [Richard_Frith_Macdon]
3ds-lm 1538 tcp 3ds-lm [Keith_Trummel] [Keith_Trummel]
3ds-lm 1538 udp 3ds-lm [Keith_Trummel] [Keith_Trummel]
vnwk-prapi 2538 tcp vnwk-prapi [John_Hasselkus] [John_Hasselkus]
vnwk-prapi 2538 udp vnwk-prapi [John_Hasselkus] [John_Hasselkus]
ibm-diradm 3538 tcp IBM Directory Server
ibm-diradm 3538 udp IBM Directory Server
swx-gate 4538 tcp Software Data Exchange Gateway [Julien_VALIENTE] [Julien_VALIENTE] 2006-05
swx-gate 4538 udp Software Data Exchange Gateway [Julien_VALIENTE] [Julien_VALIENTE] 2006-05
stuns 5349 udp STUN over DTLS [IESG] [IETF_Chair] 2014-07-03 [RFC7350] This service name was initially created by [RFC5389].
19413-19538 Unassigned
22538-22554 Unassigned

Contact Information

ID Name Organization Contact URI Last Updated
[IESG] IESG mailto:iesg&ietf.org
[IETF_Chair] IETF Chair IETF mailto:chair&ietf.org
[John_Hasselkus] John Hasselkus mailto:Jhasselkus&visualnetworks.com
[Julien_VALIENTE] Julien VALIENTE mailto:j.valiente&objectif-software.com 2006-05
[Keith_Trummel] Keith Trummel mailto:ktrummel&autodesk.com
[Richard_Frith_Macdon] Richard Frith-Macdonald mailto:richard&brainstorm.co.uk