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
ideafarm-panic 903 tcp self documenting Telnet Panic Door [Wo_o_Ideafarm] [Wo_o_Ideafarm]
ideafarm-panic 903 udp self documenting Panic Door: send 0x00 for info [Wo_o_Ideafarm] [Wo_o_Ideafarm]
linkname 1903 tcp Local Link Name Resolution [Dan_Harrington] [Dan_Harrington]
linkname 1903 udp Local Link Name Resolution [Dan_Harrington] [Dan_Harrington]
suitcase 2903 tcp SUITCASE [Milton_E_Sagen] [Milton_E_Sagen]
suitcase 2903 udp SUITCASE [Milton_E_Sagen] [Milton_E_Sagen]
charsetmgr 3903 tcp CharsetMGR [Tatsuya_Ueda] [Tatsuya_Ueda] 2003-10
charsetmgr 3903 udp CharsetMGR [Tatsuya_Ueda] [Tatsuya_Ueda] 2003-10
4903-4911 Unassigned
ff-ice 5903 tcp Flight & Flow Info for Collaborative Env [International_Civil_Aviation_Organisation] [Greg_Saccone] 2022-06-03 Defined TXT keys: FF-ICE
ff-ice 5903 udp Flight & Flow Info for Collaborative Env [International_Civil_Aviation_Organisation] [Greg_Saccone] 2022-06-03 Defined TXT keys: FF-ICE
ff-ice 5903 sctp Flight & Flow Info for Collaborative Env [International_Civil_Aviation_Organisation] [Greg_Saccone] 2022-06-03 Defined TXT keys: FF-ICE
tnos-dps 7903 tcp TNOS Secure DiaguardProtocol [Rene_Kurt] [Rene_Kurt] 2005-08
tnos-dps 7903 udp TNOS Secure DiaguardProtocol [Rene_Kurt] [Rene_Kurt] 2005-08
9903 tcp Reserved
multicast-ping 9903 udp Multicast Ping Protocol 2011-12-09 [RFC6450]
niprobe 25903 tcp NIProbe [Roman_Oliynyk] [Roman_Oliynyk]
niprobe 25903 udp NIProbe [Roman_Oliynyk] [Roman_Oliynyk]

Contact Information

ID Name Organization Contact URI Last Updated
[Dan_Harrington] Dan Harrington mailto:dth&lucent.com
[Greg_Saccone] Greg Saccone mailto:gregory.t.saccone&boeing.com 2022-08-08
[International_Civil_Aviation_Organisation] International Civil Aviation Organisation (ICAO) mailto:gisinbox&icao.int 2024-11-19
[Milton_E_Sagen] Milton E. Sagen mailto:msagen&extensis.com
[Rene_Kurt] Rene Kurt mailto:rene.kurt&adasoft.ch 2005-08
[Roman_Oliynyk] Roman Oliynyk mailto:romano&netinst.com
[Tatsuya_Ueda] Tatsuya Ueda mailto:tatsu&ist.fujitsu.com 2003-10
[Wo_o_Ideafarm] Wo'o Ideafarm mailto:b85f3c23.9ad6f42c&ideafarm.com