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
remotefs 556 tcp rfs server
remotefs 556 udp rfs server
veritas-pbx 1556 tcp VERITAS Private Branch Exchange

IANA assigned this well-formed service name as a replacement for "veritas_pbx".
[Stefan_Winkel] [Stefan_Winkel] 2004-04
veritas_pbx 1556 tcp VERITAS Private Branch Exchange [Stefan_Winkel] [Stefan_Winkel] 2004-04 This entry is an alias to "veritas-pbx". This entry is now historic, not usable for use with many common service discovery mechanisms.
veritas-pbx 1556 udp VERITAS Private Branch Exchange

IANA assigned this well-formed service name as a replacement for "veritas_pbx".
[Stefan_Winkel] [Stefan_Winkel] 2004-04
veritas_pbx 1556 udp VERITAS Private Branch Exchange [Stefan_Winkel] [Stefan_Winkel] 2004-04 This entry is an alias to "veritas-pbx". This entry is now historic, not usable for use with many common service discovery mechanisms.
nicetec-nmsvc 2556 tcp nicetec-nmsvc
nicetec-nmsvc 2556 udp nicetec-nmsvc
sky-transport 3556 tcp Sky Transport Protocol [Michael_Paddon] [Michael_Paddon] 2002-07
sky-transport 3556 udp Sky Transport Protocol [Michael_Paddon] [Michael_Paddon] 2002-07
dtn-bundle 4556 tcp DTN Bundle TCP CL Protocol [IESG] [IETF_Chair] 2021-02-22 [RFC9174]
dtn-bundle 4556 udp DTN Bundle UDP CL Protocol 2006-11 2014-02-21 [RFC7122]
dtn-bundle 4556 dccp DTN Bundle DCCP CL Protocol 2013-11-12 2014-02-21 [RFC7122] 1685351985
freeciv 5556 tcp Freeciv gameplay [Reinier_Post_and_Pau] [Reinier_Post_and_Pau] 2006-01 Known Unauthorized Use on port 5556
freeciv 5556 udp Freeciv gameplay [Reinier_Post_and_Pau] [Reinier_Post_and_Pau] 2006-01 Known Unauthorized Use on port 5556
5558-5564 Unassigned
dp-bura 5565 tcp Data Protector BURA [Micro_Focus] [Shishir_Misra] 2016-01-13 2019-10-04
5565 udp Reserved
westec-connect 5566 tcp Westec Connect [Jon_Bolen] [Jon_Bolen] 2009-03-18
5566 udp Reserved
dof-dps-mc-sec 5567 tcp DOF Protocol Stack Multicast/Secure Transport [OpenDOF] [Bryant_Eastham] 2004-11 2015-04-23
dof-dps-mc-sec 5567 udp DOF Protocol Stack Multicast/Secure Transport [OpenDOF] [Bryant_Eastham] 2004-11 2015-04-23
sdt 5568 tcp Session Data Transport Multicast [Daniel_W_Antonuk] [Daniel_W_Antonuk] 2006-05
sdt 5568 udp Session Data Transport Multicast [Daniel_W_Antonuk] [Daniel_W_Antonuk] 2006-05
rdmnet-ctrl 5569 tcp PLASA E1.33, Remote Device Management (RDM) controller status notifications [PLASA] [Simon_Newton] 2012-06-01
rdmnet-device 5569 udp PLASA E1.33, Remote Device Management (RDM) messages [PLASA] [Simon_Newton] 2012-06-01
checkmk-agent 6556 tcp Checkmk Monitoring Agent [Checkmk_GmbH] [Alexander_Wilms] 2020-07-14 2024-08-06
6556 udp Reserved
8556-8566 Unassigned
9556-9558 Unassigned
15556-15659 Unassigned
17556-17728 Unassigned
22556-22762 Unassigned
47101-47556 Unassigned
com-bardac-dw 48556 tcp com-bardac-dw [Nicholas_J_Howes] [Nicholas_J_Howes]
com-bardac-dw 48556 udp com-bardac-dw [Nicholas_J_Howes] [Nicholas_J_Howes]

Contact Information

ID Name Organization Contact URI Last Updated
[Alexander_Wilms] Alexander Wilms Checkmk GmbH mailto:alex.wilms&checkmk.com 2024-08-06
[Bryant_Eastham] Bryant Eastham OenDOF mailto:protocol&opendof.org 2015-04-23
[Checkmk_GmbH] Checkmk GmbH mailto:alex.wilms&checkmk.com 2024-08-06
[Daniel_W_Antonuk] Daniel W. Antonuk mailto:dantonuk&etcconnect.com 2006-05
[IESG] IESG mailto:iesg&ietf.org
[IETF_Chair] IETF Chair IETF mailto:chair&ietf.org
[Jon_Bolen] Jon Bolen mailto:jon.bolen&westec.net 2009-03-18
[Michael_Paddon] Michael Paddon mailto:michael.paddon&activesky.com 2002-07
[Micro_Focus] Micro Focus mailto:swpdl.dp.rd&microfocus.com 2019-09-30
[Nicholas_J_Howes] Nicholas J Howes mailto:nick&ghostwood.org
[OpenDOF] OpenDOF mailto:protocol&opendof.org 2015-04-23
[PLASA] PLASA mailto:standards.na&plasa.org 2012-06-01
[Reinier_Post_and_Pau] Reinier Post and Paul Zastoupil mailto:freeciv&freeciv.org 2006-01
[Shishir_Misra] Shishir Misra mailto:shishir.misra&microfocus.com 2019-09-30
[Simon_Newton] Simon Newton mailto:simon&nomis52.net 2012-06-01
[Stefan_Winkel] Stefan Winkel mailto:stefan&veritas.com 2004-04