Internet Assigned Numbers Authority

Service Name and Transport Protocol Port Number Registry

Last Updated
2025-08-15
Expert(s)
TCP/UDP: Joe Touch; Eliot Lear, Kumiko Ono, Wes Eddy, Brian Trammell, 
Jana Iyengar, 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
2 tcp Reserved 2025-02-13 De-assigned on 2025-02-13, previously compressnet by [Bernie_Volz]
2 udp Reserved 2025-02-13 De-assigned on 2025-02-13, previously compressnet by [Bernie_Volz]
3 tcp Reserved 2025-02-13 De-assigned on 2025-02-13, previously compressnet by [Bernie_Volz]
3 udp Reserved 2025-02-13 De-assigned on 2025-02-13, previously compressnet by [Bernie_Volz]
discard 9 sctp Discard [Randall_Stewart] [Randall_Stewart] 2022-02-07 [RFC9260]
12 tcp Unassigned
12 udp Unassigned
ftp-data 20 tcp File Transfer [Default Data] [Jon_Postel] [Jon_Postel]
ftp-data 20 udp File Transfer [Default Data] [Jon_Postel] [Jon_Postel]
ftp-data 20 sctp FTP [Randall_Stewart] [Randall_Stewart] 2022-02-07 [RFC9260]
ftp 21 tcp File Transfer Protocol [Control] [Jon_Postel] [Jon_Postel] [RFC959] Defined TXT keys: u=<username> p=<password> path=<path>
ftp 21 udp File Transfer Protocol [Control] [Jon_Postel] [Jon_Postel] [RFC959] Defined TXT keys: u=<username> p=<password> path=<path>
ftp 21 sctp FTP [Randall_Stewart] [Randall_Stewart] 2022-02-07 [RFC9260] Defined TXT keys: u=<username> p=<password> path=<path>
ssh 22 tcp The Secure Shell (SSH) Protocol [RFC4251] Defined TXT keys: u=<username> p=<password>
ssh 22 udp The Secure Shell (SSH) Protocol [RFC4251] Defined TXT keys: u=<username> p=<password>
ssh 22 sctp SSH [Randall_Stewart] [Randall_Stewart] 2022-02-07 [RFC9260] Defined TXT keys: u=<username> p=<password>
telnet 23 tcp Telnet [Jon_Postel] [Jon_Postel] [RFC854] Defined TXT keys: u=<username> p=<password>
telnet 23 udp Telnet [Jon_Postel] [Jon_Postel] [RFC854] Defined TXT keys: u=<username> p=<password>
24 tcp any private mail system [Rick_Adams] [Rick_Adams]
24 udp any private mail system [Rick_Adams] [Rick_Adams]
smtp 25 tcp Simple Mail Transfer [IESG] [IETF_Chair] 2017-06-05 [RFC-ietf-emailcore-rfc5321bis-43]
smtp 25 udp Simple Mail Transfer [IESG] [IETF_Chair] 2017-06-05 [RFC-ietf-emailcore-rfc5321bis-43]
26 tcp Unassigned
26 udp Unassigned
nsw-fe 27 tcp NSW User System FE [Robert_Thomas] [Robert_Thomas]
nsw-fe 27 udp NSW User System FE [Robert_Thomas] [Robert_Thomas]
28 tcp Unassigned
28 udp Unassigned
msg-icp 29 tcp MSG ICP [Robert_Thomas] [Robert_Thomas]
msg-icp 29 udp MSG ICP [Robert_Thomas] [Robert_Thomas]
32 tcp Unassigned
32 udp Unassigned
name 42 tcp Host Name Server
name 42 udp Host Name Server
nameserver 42 tcp Host Name Server
nameserver 42 udp Host Name Server
47 tcp Reserved 2017-05-18 This entry has been removed on 2017-05-18.
47 udp Reserved 2017-05-18 This entry has been removed on 2017-05-18.
51 Reserved 2013-05-24 This entry is being removed on 2013-05-24.
xns-time 52 tcp XNS Time Protocol [Susie_Armstrong] [Susie_Armstrong]
xns-time 52 udp XNS Time Protocol [Susie_Armstrong] [Susie_Armstrong]
61 tcp Reserved 2017-05-18 This entry has been removed on 2017-05-18.
61 udp Reserved 2017-05-18 This entry has been removed on 2017-05-18.
acas 62 tcp ACA Services [E_Wald] [E_Wald]
acas 62 udp ACA Services [E_Wald] [E_Wald]
netrjs-2 72 tcp Remote Job Service
netrjs-2 72 udp Remote Job Service
http 80 sctp HTTP [Randall_Stewart] [Randall_Stewart] 2022-02-07 [RFC9260] Defined TXT keys: u=<username> p=<password> path=<path to document>
xfer 82 tcp XFER Utility [Thomas_M_Smith] [Thomas_M_Smith]
xfer 82 udp XFER Utility [Thomas_M_Smith] [Thomas_M_Smith]
kerberos 88 tcp Kerberos [B_Clifford_Neuman] [B_Clifford_Neuman] 2022-02-18 [RFC4120]
kerberos 88 udp Kerberos [B_Clifford_Neuman] [B_Clifford_Neuman] 2022-02-18 [RFC4120]
npp 92 tcp Network Printing Protocol [Louis_Mamakos] [Louis_Mamakos]
npp 92 udp Network Printing Protocol [Louis_Mamakos] [Louis_Mamakos]
iso-tsap 102 tcp ISO-TSAP Class 0 [Marshall_Rose] [Marshall_Rose]
iso-tsap 102 udp ISO-TSAP Class 0 [Marshall_Rose] [Marshall_Rose]
pop2 109 tcp Post Office Protocol - Version 2 [Joyce_K_Reynolds] [Joyce_K_Reynolds]
pop2 109 udp Post Office Protocol - Version 2 [Joyce_K_Reynolds] [Joyce_K_Reynolds]
mcidas 112 tcp McIDAS Data Transmission Protocol [Glenn_Davis] [Glenn_Davis]
mcidas 112 udp McIDAS Data Transmission Protocol [Glenn_Davis] [Glenn_Davis]
114 unassigned Deprecated June 2004
cfdptkt 120 tcp CFDPTKT [John_Ioannidis] [John_Ioannidis]
cfdptkt 120 udp CFDPTKT [John_Ioannidis] [John_Ioannidis]
erpc 121 tcp Encore Expedited Remote Pro.Call [Jack_ONeil] [Jack_ONeil]
erpc 121 udp Encore Expedited Remote Pro.Call [Jack_ONeil] [Jack_ONeil]
smakynet 122 tcp SMAKYNET [Pierre_Arnaud] [Pierre_Arnaud]
smakynet 122 udp SMAKYNET [Pierre_Arnaud] [Pierre_Arnaud]
ntp 123 tcp Network Time Protocol [Dave_Mills] [Dave_Mills] [RFC5905]
ntp 123 udp Network Time Protocol [Dave_Mills] [Dave_Mills] [RFC5905]
ansatrader 124 tcp ANSA REX Trader [Nicola_J_Howarth] [Nicola_J_Howarth]
ansatrader 124 udp ANSA REX Trader [Nicola_J_Howarth] [Nicola_J_Howarth]
locus-map 125 tcp Locus PC-Interface Net Map Ser [Eric_Peterson] [Eric_Peterson]
locus-map 125 udp Locus PC-Interface Net Map Ser [Eric_Peterson] [Eric_Peterson]
nxedit 126 tcp NXEdit [Don_Payette] [Don_Payette] Port 126 Previously assigned to application below unitary 126/tcp Unisys Unitary Login unitary 126/udp Unisys Unitary Login <feil&kronos.nisd.cam.unisys.com> Port 126 Previously assigned to application above
nxedit 126 udp NXEdit [Don_Payette] [Don_Payette] Port 126 Previously assigned to application below unitary 126/tcp Unisys Unitary Login unitary 126/udp Unisys Unitary Login <feil&kronos.nisd.cam.unisys.com> Port 126 Previously assigned to application above
locus-con 127 tcp Locus PC-Interface Conn Server [Eric_Peterson] [Eric_Peterson]
locus-con 127 udp Locus PC-Interface Conn Server [Eric_Peterson] [Eric_Peterson]
gss-xlicen 128 tcp GSS X License Verification [John_Light] [John_Light]
gss-xlicen 128 udp GSS X License Verification [John_Light] [John_Light]
pwdgen 129 tcp Password Generator Protocol [Frank_J_Wacho] [Frank_J_Wacho]
pwdgen 129 udp Password Generator Protocol [Frank_J_Wacho] [Frank_J_Wacho]
cisco-sys 132 tcp cisco SYSMAINT
cisco-sys 132 udp cisco SYSMAINT
statsrv 133 tcp Statistics Service [Dave_Mills_2] [Dave_Mills_2]
statsrv 133 udp Statistics Service [Dave_Mills_2] [Dave_Mills_2]
bl-idm 142 tcp Britton-Lee IDM [Susie_Snitzer] [Susie_Snitzer]
bl-idm 142 udp Britton-Lee IDM [Susie_Snitzer] [Susie_Snitzer]
aed-512 149 tcp AED 512 Emulation Service [Albert_G_Broscius] [Albert_G_Broscius]
aed-512 149 udp AED 512 Emulation Service [Albert_G_Broscius] [Albert_G_Broscius]
bftp 152 tcp Background File Transfer Program [Annette_DeSchon] [Annette_DeSchon]
bftp 152 udp Background File Transfer Program [Annette_DeSchon] [Annette_DeSchon]
snmptrap 162 tcp SNMPTRAP [Marshall_Rose] [Marshall_Rose]
snmptrap 162 udp SNMPTRAP [Marshall_Rose] [Marshall_Rose]
xns-courier 165 tcp Xerox [Susie_Armstrong_2] [Susie_Armstrong_2]
xns-courier 165 udp Xerox [Susie_Armstrong_2] [Susie_Armstrong_2]
cl-1 172 tcp Network Innovations CL/1

IANA assigned this well-formed service name as a replacement for "cl/1".
[Kevin_DeVault] [Kevin_DeVault]
cl/1 172 tcp Network Innovations CL/1 [Kevin_DeVault] [Kevin_DeVault] This entry is an alias to "cl-1". This entry is now historic, not usable for use with many common service discovery mechanisms.
cl-1 172 udp Network Innovations CL/1

IANA assigned this well-formed service name as a replacement for "cl/1".
[Kevin_DeVault] [Kevin_DeVault]
cl/1 172 udp Network Innovations CL/1 [Kevin_DeVault] [Kevin_DeVault] This entry is an alias to "cl-1". This entry is now historic, not usable for use with many common service discovery mechanisms.
bgp 179 sctp BGP [Randall_Stewart] [Randall_Stewart] 2022-02-07 [RFC9260]

Contact Information

ID Name Organization Contact URI Last Updated
[Albert_G_Broscius] Albert G. Broscius mailto:broscius&dsl.cis.upenn.edu
[Annette_DeSchon] Annette DeSchon mailto:DESCHON&isi.edu
[B_Clifford_Neuman] B. Clifford Neuman mailto:bcn&isi.edu 2022-02-18
[Bernie_Volz] Bernie Volz mailto:volz&cisco.com
[Dave_Mills] Dave Mills mailto:mills&udel.edu 2022-06-03
[Dave_Mills_2] Dave Mills mailto:Mills&huey.udel.edu
[Don_Payette] Don Payette mailto:Don.Payette&unisys.com
[E_Wald] E. Wald mailto:ewald&via.enet.dec.com
[Eric_Peterson] Eric Peterson mailto:lcc.eric&seas.ucla.edu
[Frank_J_Wacho] Frank J. Wacho mailto:WANCHO&wsmr-simtel20.army.mil
[Glenn_Davis] Glenn Davis mailto:support&unidata.ucar.edu
[IESG] IESG mailto:iesg&ietf.org
[IETF_Chair] IETF Chair IETF mailto:chair&ietf.org
[Jack_ONeil] Jack O'Neil
[John_Ioannidis] John Ioannidis mailto:ji&close.cs.columbia.ed
[John_Light] John Light mailto:johnl&gssc.gss.com
[Jon_Postel] Jon Postel mailto:postel&isi.edu
[Joyce_K_Reynolds] Joyce K. Reynolds mailto:jkrey&isi.edu
[Kevin_DeVault] Kevin DeVault
[Louis_Mamakos] Louis Mamakos mailto:louie&sayshell.umd.edu
[Marshall_Rose] Marshall Rose mailto:mrose17&gmail.com 2024-07-29
[Nicola_J_Howarth] Nicola J. Howarth mailto:njh&ansa.co.uk
[Pierre_Arnaud] Pierre Arnaud mailto:pierre.arnaud&iname.com
[Randall_Stewart] Randall Stewart IETF TSVWG mailto:rrs&lakerest.net
[Rick_Adams] Rick Adams mailto:rick&uunet.uu.net
[Robert_Thomas] Robert Thomas mailto:BThomas&f.bbn.com
[Susie_Armstrong] Susie Armstrong mailto:Armstrong.wbst128@xerox
[Susie_Armstrong_2] Susie Armstrong mailto:Armstrong.wbst128&xerox.com
[Susie_Snitzer] Susie Snitzer
[Thomas_M_Smith] Thomas M. Smith mailto:Thomas.M.Smith&lmco.com