Service Name and Transport Protocol Port Number Registry

Last Updated
2026-09-07
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
opc-job-start 423 tcp IBM Operations Planning and Control Start
opc-job-start 423 udp IBM Operations Planning and Control Start
essbase 1423 tcp Essbase Arbor Software
essbase 1423 udp Essbase Arbor Software
rnrp 2423 tcp RNRP [Per_Sahlqvist] [Per_Sahlqvist]
rnrp 2423 udp RNRP [Per_Sahlqvist] [Per_Sahlqvist]
xtrm 3423 tcp xTrade Reliable Messaging
xtrm 3423 udp xTrade Reliable Messaging
thingkit 4423 tcp thingkit secure mesh [thingkit_inc.] [Chris_Bell] 2016-06-27
4423 udp Reserved
virtualuser 5423 tcp VIRTUALUSER [Chad_Williams] [Chad_Williams]
virtualuser 5423 udp VIRTUALUSER [Chad_Williams] [Chad_Williams]
aritts 8423 tcp Aristech text-to-speech server [Aristech_GmbH] [Martin_Mende] 2017-03-30 2022-02-22
8423 udp Reserved
slmap 36423 sctp SLm Interface Application Protocol [_3GPP_4] [Kimmo_Kymalainen] 2015-06-18
38423-38461 Unassigned

Contact Information

ID Name Organization Contact URI Last Updated
[_3GPP_4] 3GPP mailto:kimmo.kymalainen&etsi.org 2015-06-18
[Aristech_GmbH] Aristech GmbH mailto:aritts&aristech.de 2022-02-22
[Chad_Williams] Chad Williams mailto:chad&apple.com
[Chris_Bell] Chris Bell mailto:cb&thingkit.co 2016-06-27
[Kimmo_Kymalainen] Kimmo Kymalainen mailto:kimmo.kymalainen&etsi.org 2017-05-08
[Martin_Mende] Martin Mende Aristech GmbH mailto:martin.mende&aristech.de 2022-02-22
[Per_Sahlqvist] Per Sahlqvist mailto:psahlqvi&sw.seisy.abb.se
[thingkit_inc.] thingkit, inc. mailto:cb&thingkit.co 2016-06-27