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
re-mail-ck 50 tcp Remote Mail Checking Protocol [Steve_Dorner] [Steve_Dorner]
re-mail-ck 50 udp Remote Mail Checking Protocol [Steve_Dorner] [Steve_Dorner]
imap 143 tcp Internet Message Access Protocol [IESG] [IETF_Chair] 2021-02-22 [RFC3501][RFC9051]
sql-net 150 tcp SQL-NET [Martin_Picard] [Martin_Picard]
sql-net 150 udp SQL-NET [Martin_Picard] [Martin_Picard]
z39-50 210 tcp ANSI Z39.50

IANA assigned this well-formed service name as a replacement for "z39.50".
[Mark_H_Needleman] [Mark_H_Needleman]
z39.50 210 tcp ANSI Z39.50 [Mark_H_Needleman] [Mark_H_Needleman] This entry is an alias to "z39-50". This entry is now historic, not usable for use with many common service discovery mechanisms.
z39-50 210 udp ANSI Z39.50

IANA assigned this well-formed service name as a replacement for "z39.50".
[Mark_H_Needleman] [Mark_H_Needleman]
z39.50 210 udp ANSI Z39.50 [Mark_H_Needleman] [Mark_H_Needleman] This entry is an alias to "z39-50". This entry is now historic, not usable for use with many common service discovery mechanisms.
matip-type-a 350 tcp MATIP Type A [Alain_Robert] [Alain_Robert] [RFC2351]
matip-type-a 350 udp MATIP Type A [Alain_Robert] [Alain_Robert] [RFC2351]
tserver 450 tcp Computer Supported Telecomunication Applications [Harvey_S_Schultz] [Harvey_S_Schultz]
tserver 450 udp Computer Supported Telecomunication Applications [Harvey_S_Schultz] [Harvey_S_Schultz]
isakmp 500 tcp isakmp [Mark_Schertler] [Mark_Schertler]
isakmp 500 udp isakmp [Mark_Schertler] [Mark_Schertler]
stmf 501 tcp STMF [Alan_Ungar] [Alan_Ungar]
stmf 501 udp STMF [Alan_Ungar] [Alan_Ungar]
mbap 502 tcp Modbus Application Protocol [modbus.org] [Dennis_Dube] 2014-06-10
mbap 502 udp Modbus Application Protocol [modbus.org] [Dennis_Dube] 2014-06-10
intrinsa 503 tcp Intrinsa [Robert_Ford] [Robert_Ford]
intrinsa 503 udp Intrinsa [Robert_Ford] [Robert_Ford]
citadel 504 tcp citadel [Art_Cancro] [Art_Cancro]
citadel 504 udp citadel [Art_Cancro] [Art_Cancro]
mailbox-lm 505 tcp mailbox-lm [Beverly_Moody] [Beverly_Moody]
mailbox-lm 505 udp mailbox-lm [Beverly_Moody] [Beverly_Moody]
ohimsrv 506 tcp ohimsrv [Scott_Powell] [Scott_Powell]
ohimsrv 506 udp ohimsrv [Scott_Powell] [Scott_Powell]
crs 507 tcp crs [Brad_Wright] [Brad_Wright]
crs 507 udp crs [Brad_Wright] [Brad_Wright]
xvttp 508 tcp xvttp [Keith_J_Alphonso] [Keith_J_Alphonso]
xvttp 508 udp xvttp [Keith_J_Alphonso] [Keith_J_Alphonso]
snare 509 tcp snare [Dennis_Batchelder] [Dennis_Batchelder]
snare 509 udp snare [Dennis_Batchelder] [Dennis_Batchelder]
new-rwho 550 tcp new-who [n/a]
new-rwho 550 udp new-who [n/a]
obex 650 tcp OBEX [Jeff_Garbers] [Jeff_Garbers]
obex 650 udp OBEX [Jeff_Garbers] [Jeff_Garbers]
rfile 750 tcp
loadav 750 udp
kerberos-iv 750 udp kerberos version iv [Martin_Hamilton] [Martin_Hamilton]
domain-s 853 udp DNS query-response protocol run over DTLS or QUIC [IESG] [IETF_Chair] 2015-10-08 2022-04-01 [RFC7858][RFC8094][RFC9250]
imaps 993 tcp IMAP over TLS protocol [IESG] [IETF_Chair] 2021-02-22 [RFC3501][RFC8314][RFC9051]
cma 1050 tcp CORBA Management Agent [Ramy_Zaarour] [Ramy_Zaarour]
cma 1050 udp CORBA Management Agent [Ramy_Zaarour] [Ramy_Zaarour]
blaze 1150 tcp Blaze File Server [Curt_Schimmel] [Curt_Schimmel] 2005-11
blaze 1150 udp Blaze File Server [Curt_Schimmel] [Curt_Schimmel] 2005-11
swldy-sias 1250 tcp swldy-sias [Peter_E_Williams] [Peter_E_Williams]
swldy-sias 1250 udp swldy-sias [Peter_E_Williams] [Peter_E_Williams]
editbench 1350 tcp Registration Network Protocol [Simson_L_Garfinkel] [Simson_L_Garfinkel]
editbench 1350 udp Registration Network Protocol [Simson_L_Garfinkel] [Simson_L_Garfinkel]
dwf 1450 tcp Tandem Distributed Workbench Facility [Mike_Bert] [Mike_Bert]
dwf 1450 udp Tandem Distributed Workbench Facility [Mike_Bert] [Mike_Bert]
vlsi-lm 1500 tcp VLSI License Manager [Shue_Lin_Kuo] [Shue_Lin_Kuo]
vlsi-lm 1500 udp VLSI License Manager [Shue_Lin_Kuo] [Shue_Lin_Kuo]
saiscm 1501 tcp Satellite-data Acquisition System 3 [Bill_Taylor] [Bill_Taylor]
saiscm 1501 udp Satellite-data Acquisition System 3 [Bill_Taylor] [Bill_Taylor]
shivadiscovery 1502 tcp Shiva [Jonathan_Wenocur] [Jonathan_Wenocur]
shivadiscovery 1502 udp Shiva [Jonathan_Wenocur] [Jonathan_Wenocur]
imtc-mcs 1503 tcp Databeam [Jim_Johnston] [Jim_Johnston]
imtc-mcs 1503 udp Databeam [Jim_Johnston] [Jim_Johnston]
evb-elm 1504 tcp EVB Software Engineering License Manager [B_G_Mahesh] [B_G_Mahesh]
evb-elm 1504 udp EVB Software Engineering License Manager [B_G_Mahesh] [B_G_Mahesh]
funkproxy 1505 tcp Funk Software, Inc. [Robert_D_Vincent] [Robert_D_Vincent]
funkproxy 1505 udp Funk Software, Inc. [Robert_D_Vincent] [Robert_D_Vincent]
utcd 1506 tcp Universal Time daemon (utcd) [Walter_Poxon] [Walter_Poxon]
utcd 1506 udp Universal Time daemon (utcd) [Walter_Poxon] [Walter_Poxon]
symplex 1507 tcp symplex [Mike_Turley] [Mike_Turley]
symplex 1507 udp symplex [Mike_Turley] [Mike_Turley]
diagmond 1508 tcp diagmond [Pete_Moscatelli] [Pete_Moscatelli]
diagmond 1508 udp diagmond [Pete_Moscatelli] [Pete_Moscatelli]
robcad-lm 1509 tcp Robcad, Ltd. License Manager [Hindin_Joseph] [Hindin_Joseph]
robcad-lm 1509 udp Robcad, Ltd. License Manager [Hindin_Joseph] [Hindin_Joseph]
3m-image-lm 1550 tcp Image Storage license manager 3M Company [J_C_Canessa] [J_C_Canessa]
3m-image-lm 1550 udp Image Storage license manager 3M Company [J_C_Canessa] [J_C_Canessa]
nkd 1650 tcp nkdn
nkd 1650 udp nkd
sslp 1750 tcp Simple Socket Library's PortMaster [Dr_Charles_E_Campb] [Dr_Charles_E_Campb]
sslp 1750 udp Simple Socket Library's PortMaster [Dr_Charles_E_Campb] [Dr_Charles_E_Campb]
gsi 1850 tcp GSI [William_Mullaney] [William_Mullaney]
gsi 1850 udp GSI [William_Mullaney] [William_Mullaney]
ismaeasdaqtest 1950 tcp ISMA Easdaq Test [Stephen_Dunne] [Stephen_Dunne]
ismaeasdaqtest 1950 udp ISMA Easdaq Test [Stephen_Dunne] [Stephen_Dunne]
av-emb-config 2050 tcp Avaya EMB Config Port [John_Yeager] [John_Yeager]
av-emb-config 2050 udp Avaya EMB Config Port [John_Yeager] [John_Yeager]
h2250-annex-g 2099 tcp H.225.0 Annex G Signalling [ITU-T] [ITU-T_TSB] 2013-01-31
h2250-annex-g 2099 udp H.225.0 Annex G Signalling [ITU-T] [ITU-T_TSB] 2013-01-31
tdmoip 2142 tcp TDM OVER IP [Yaakov_Stein] [Yaakov_Stein] 2016-09-21 [RFC5087]
tdmoip 2142 udp TDM OVER IP [Yaakov_Stein] [Yaakov_Stein] 2016-09-21 [RFC5087]
dynamic3d 2150 tcp DYNAMIC3D [Tobias_Wegner] [Tobias_Wegner]
dynamic3d 2150 udp DYNAMIC3D [Tobias_Wegner] [Tobias_Wegner]
remote-collab 2250 tcp remote-collab [Richard_Walters] [Richard_Walters]
remote-collab 2250 udp remote-collab [Richard_Walters] [Richard_Walters]
apx500api-1 2264 tcp Audio Precision Apx500 API Port 1
apx500api-1 2264 udp Audio Precision Apx500 API Port 1
apx500api-2 2265 tcp Audio Precision Apx500 API Port 2 [Robert_Wright] [Robert_Wright]
apx500api-2 2265 udp Audio Precision Apx500 API Port 2 [Robert_Wright] [Robert_Wright]
amt 2268 tcp AMT [IESG] [IETF_Chair] 2004-12 2014-12-17 [RFC7450]
amt 2268 udp AMT [IESG] [IETF_Chair] 2004-12 2014-12-17 [RFC7450]
psbserver 2350 tcp Pharos Booking Server
psbserver 2350 udp Pharos Booking Server

Contact Information

ID Name Organization Contact URI Last Updated
[Alain_Robert] Alain Robert mailto:arobert&par.sita.int
[Alan_Ungar] Alan Ungar mailto:aungar&farradyne.com
[Art_Cancro] Art Cancro mailto:ajc&citadel.org 2015-02-18
[B_G_Mahesh] B.G. Mahesh mailto:mahesh&sett.com
[Beverly_Moody] Beverly Moody mailto:Beverly_Moody&stercomm.com
[Bill_Taylor] Bill Taylor mailto:sais&ssec.wisc.edu
[Brad_Wright] Brad Wright mailto:bradwr&microsoft.com
[Curt_Schimmel] Curt Schimmel mailto:curt&small-tree.com 2005-11
[Dennis_Batchelder] Dennis Batchelder mailto:dennis&capres.com
[Dennis_Dube] Dennis Dube mailto:dennis.dube&schneider-electric.com 2014-06-10
[Dr_Charles_E_Campb] Dr. Charles E. Campbell Jr. mailto:cec&gryphon.gsfc.nasa.gov
[Harvey_S_Schultz] Harvey S. Schultz mailto:harvey&acm.org
[Hindin_Joseph] Hindin Joseph mailto:hindin%25robcad@uunet.uu.net
[IESG] IESG mailto:iesg&ietf.org
[IETF_Chair] IETF Chair IETF mailto:chair&ietf.org
[ITU-T] ITU-T mailto:tsbsg16&itu.int 2013-01-31
[ITU-T_TSB] ITU-T TSB ITU-T mailto:tsbsg16&itu.int 2013-01-31
[J_C_Canessa] J. C. Canessa mailto:jccanessa&mmm.com
[Jeff_Garbers] Jeff Garbers mailto:FJG030&email.mot.com
[Jim_Johnston] Jim Johnston mailto:jjohnston&databeam.com
[John_Yeager] John Yeager mailto:johnyeager&avaya.com
[Jonathan_Wenocur] Jonathan Wenocur mailto:jhw&shiva.com
[Keith_J_Alphonso] Keith J. Alphonso mailto:alphonso&ncs-ssc.com
[Mark_H_Needleman] Mark H. Needleman mailto:markn&sirsi.com
[Mark_Schertler] Mark Schertler mailto:mjs&tycho.ncsc.mil
[Martin_Hamilton] Martin Hamilton mailto:martin&mrrl.lut.as.uk
[Martin_Picard] Martin Picard
[Mike_Bert] Mike Bert mailto:BERG_MIKE&tandem.com
[Mike_Turley] Mike Turley mailto:turley&symplex.com
[modbus.org] modbus.org mailto:rbelliardi&modbus.org 2014-06-10
[Pete_Moscatelli] Pete Moscatelli mailto:moscat&hprdstl0.rose.hp.com
[Peter_E_Williams] Peter E Williams mailto:peter.williams&smallworld-us.com
[Ramy_Zaarour] Ramy Zaarour mailto:ramy&lumos.com
[Richard_Walters] Richard Walters mailto:walters&cs.ucdavis.edu
[Robert_D_Vincent] Robert D. Vincent mailto:bert&willowpond.com
[Robert_Ford] Robert Ford mailto:robert&intrinsa.com
[Robert_Wright] Robert Wright, Founder and Principal Engineer Audio Precision Inc. mailto:ianaports&ap.com 2006-05
[Scott_Powell] Scott Powell mailto:spowell&openhorizon.com
[Shue_Lin_Kuo] Shue-Lin Kuo mailto:shuelin&mdk.sanjose.vlsi.com
[Simson_L_Garfinkel] Simson L. Garfinkel mailto:simsong&next.cambridge.ma.us
[Stephen_Dunne] Stephen Dunne mailto:sdun&isma.co.uk
[Steve_Dorner] Steve Dorner mailto:s-dorner&uiuc.edu
[Tobias_Wegner] Tobias Wegner mailto:wegner&novagate.de
[Walter_Poxon] Walter Poxon mailto:wdp&ironwood.cray.com
[William_Mullaney] William Mullaney mailto:mullanwi&usa.net
[Yaakov_Stein] Yaakov Stein mailto:yaakovjstein&gmail.com 2022-02-04