Service Name and Transport Protocol Port Number Registry

Last Updated
2026-09-02
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
dhcpv6-client 546 udp DHCPv6 Client [IESG] [IETF_Chair] 2018-05-21 [RFC9915]
dhcpv6-server 547 udp DHCPv6 Server [IESG] [IETF_Chair] 2018-05-21 [RFC9915]
nas 991 tcp Netnews Administration System [Vera_Heinau][Heiko_Schlichting] [Vera_Heinau][Heiko_Schlichting] 2017-02-10 [RFC4707]
nas 991 udp Netnews Administration System [Vera_Heinau][Heiko_Schlichting] [Vera_Heinau][Heiko_Schlichting] 2017-02-10 [RFC4707]
stun-p2 1991 tcp cisco STUN Priority 2 port
stun-p2 1991 udp cisco STUN Priority 2 port
wkstn-mon 2991 tcp WKSTN-MON [William_David] [William_David]
wkstn-mon 2991 udp WKSTN-MON [William_David] [William_David]
bv-smcsrv 3991 tcp BindView-SMCServer
bv-smcsrv 3991 udp BindView-SMCServer
vrt 4991 tcp VITA Radio Transport [Sam_Bretheim] [Sam_Bretheim] 2009-01-08
vrt 4991 udp VITA Radio Transport [Sam_Bretheim] [Sam_Bretheim] 2009-01-08
nuxsl 5991 tcp NUXSL [Kai_Kretschmann] [Kai_Kretschmann] 2002-03
nuxsl 5991 udp NUXSL [Kai_Kretschmann] [Kai_Kretschmann] 2002-03
netconf-tls 6513 tcp NETCONF over TLS [IESG] [IETF_Chair] 2024-01-24 [RFC7589][RFC9918]
https-wmap 8991 tcp webmail HTTPS service [Chris_Newman] [Chris_Newman] 2007-12-03
https-wmap 8991 udp webmail HTTPS service [Chris_Newman] [Chris_Newman] 2007-12-03
9910 Unassigned
sype-transport 9911 tcp SYPECom Transport Protocol [Sylvain_Pedneault] [Sylvain_Pedneault] 2003-03
sype-transport 9911 udp SYPECom Transport Protocol [Sylvain_Pedneault] [Sylvain_Pedneault] 2003-03
9912-9924 Unassigned
osm-oev 9991 tcp OSM Event Server [Vinay_Gupta] [Vinay_Gupta] 2003-08
osm-oev 9991 udp OSM Event Server [Vinay_Gupta] [Vinay_Gupta] 2003-08
10991-10999 Unassigned
intel-rci-mp 16991 tcp INTEL-RCI-MP [Jane_Dashevsky] [Jane_Dashevsky]
intel-rci-mp 16991 udp INTEL-RCI-MP [Jane_Dashevsky] [Jane_Dashevsky]

Contact Information

ID Name Organization Contact URI Last Updated
[Chris_Newman] Chris Newman mailto:chris.newman&oracle.com 2017-01-26
[Heiko_Schlichting] Heiko Schlichting mailto:heiko.schlichting&fu-berlin.de 2022-06-07
[IESG] IESG mailto:iesg&ietf.org
[IETF_Chair] IETF Chair IETF mailto:chair&ietf.org
[Jane_Dashevsky] Jane Dashevsky mailto:jane.dashevsky&intel.com
[Kai_Kretschmann] Kai Kretschmann mailto:K.Kretschmann&security-gui.de 2002-03
[Sam_Bretheim] Sam Bretheim mailto:info&opensigint.org 2009-01-08
[Sylvain_Pedneault] Sylvain Pedneault mailto:sylvain&sypecom.qc.ca 2003-03
[Vera_Heinau] Vera Heinau mailto:vera.heinau&fu-berlin.de 2022-06-07
[Vinay_Gupta] Vinay Gupta mailto:vinay.gupta&hp.com 2003-08
[William_David] William David mailto:william.david&lmco.com