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
intrinsa 503 tcp Intrinsa [Robert_Ford] [Robert_Ford]
intrinsa 503 udp Intrinsa [Robert_Ford] [Robert_Ford]
imtc-mcs 1503 tcp Databeam [Jim_Johnston] [Jim_Johnston]
imtc-mcs 1503 udp Databeam [Jim_Johnston] [Jim_Johnston]
nms-dpnss 2503 tcp NMS-DPNSS [Jean_Christophe_Desi] [Jean_Christophe_Desi]
nms-dpnss 2503 udp NMS-DPNSS [Jean_Christophe_Desi] [Jean_Christophe_Desi]
lsp-ping 3503 tcp MPLS LSP-echo Port [RFC8029]
lsp-ping 3503 udp MPLS LSP-echo Port [RFC8029]
4503 tcp Reserved
m-bus-oms 4503 udp M-Bus-OMS over UDP [OMS-Group_e._V.] [Ahmed_Kasttet] 2025-05-19
5030 tcp Reserved 2006-12 2022-01-10 Historic usage was surfpass. De-Assigned on 2022-01-10
5030 udp Reserved 2006-12 2022-01-10 Historic usage was surfpass. De-Assigned on 2022-01-10
5031 tcp Reserved
dmp 5031 udp Direct Message Protocol [Gjermund_Wallenius] [Gjermund_Wallenius] 2009-09-30
signacert-agent 5032 tcp SignaCert Enterprise Trust Server Agent [Harris_Corporation] [Daniel_R_Somerfield] 2011-08-05
5032 udp Reserved
jtnetd-server 5033 tcp Janstor Secure Data [Janstor_Technology] [Anthony_Johnson_2] 2015-06-08
5033 udp Reserved
jtnetd-status 5034 tcp Janstor Status [Janstor_Technology] [Anthony_Johnson_2] 2015-06-08
5034 udp Reserved
5035-5041 Unassigned
fcp-srvr-inst2 5503 tcp fcp-srvr-inst2 [Ken_Wittmer] [Ken_Wittmer]
fcp-srvr-inst2 5503 udp fcp-srvr-inst2 [Ken_Wittmer] [Ken_Wittmer]
boks-clntd 6503 tcp BoKS Clntd

IANA assigned this well-formed service name as a replacement for "boks_clntd".
[Magnus_Nystrom] [Magnus_Nystrom]
boks_clntd 6503 tcp BoKS Clntd [Magnus_Nystrom] [Magnus_Nystrom] This entry is an alias to "boks-clntd". This entry is now historic, not usable for use with many common service discovery mechanisms.
boks-clntd 6503 udp BoKS Clntd

IANA assigned this well-formed service name as a replacement for "boks_clntd".
[Magnus_Nystrom] [Magnus_Nystrom]
boks_clntd 6503 udp BoKS Clntd [Magnus_Nystrom] [Magnus_Nystrom] This entry is an alias to "boks-clntd". This entry is now historic, not usable for use with many common service discovery mechanisms.
lsp-self-ping 8503 udp MPLS LSP Self-Ping [IESG] [IETF_Chair] 2015-06-11 2016-02-01 [RFC7746]
8503 tcp Reserved
27443-27503 Unassigned

Contact Information

ID Name Organization Contact URI Last Updated
[Ahmed_Kasttet] Ahmed Kasttet OMS-Group e. V. (Open Metering System Group) mailto:ahmed.kasttet&oms-group.org 2025-05-19
[Anthony_Johnson_2] Anthony Johnson Janstor Technology mailto:jtadmin&janstor.com 2015-06-08
[Daniel_R_Somerfield] Daniel R Somerfield mailto:dsomerfi&harris.com 2011-08-05
[Gjermund_Wallenius] Gjermund Wallenius mailto:gwallenius&ndlocis.mil.no 2009-09-30
[Harris_Corporation] Harris, Corporation mailto:dsomerfi&harris.com 2011-08-05
[IESG] IESG mailto:iesg&ietf.org
[IETF_Chair] IETF Chair IETF mailto:chair&ietf.org
[Janstor_Technology] Janstor Technology mailto:jtadmin&janstor.com 2015-06-08
[Jean_Christophe_Desi] Jean-Christophe Desire mailto:Jean-Christophe_Desire&nms-europe.com
[Jim_Johnston] Jim Johnston mailto:jjohnston&databeam.com
[Ken_Wittmer] Ken Wittmer mailto:kenneth.m.wittmer&accenture.com
[Magnus_Nystrom] Magnus Nystrom mailto:magnus&dynas.se
[OMS-Group_e._V.] OMS-Group e. V. (Open Metering System Group) mailto:office&oms-group.org 2025-05-19
[Robert_Ford] Robert Ford mailto:robert&intrinsa.com