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]

Available Formats

CSV

XML

HTML

Plain text
Service Name Port Number Transport Protocol Description Assignee Contact Registration Date Modification Date Reference Service Code Unauthorized Use Reported Assignment Notes
dnssd-srp tcp DNS-Based Service Discovery [IESG] [IETF_Chair] 2024-04-12 2024-09-05 [RFC9665] Defined TXT keys: None
dnssd-srp-tls tcp DNS-Based Service Discovery (TLS) [IESG] [IETF_Chair] 2024-04-12 2024-09-05 [RFC9665] Defined TXT keys: None
dots-call-home tcp DOTS Signal Channel Call Home Protocol. The service name is used to construct the SRV service names "_dots-call-home._udp" and "_dots-call-home._tcp" for discovering Call Home DOTS clients used to establish DOTS signal channel call home. [IESG] [IETF_Chair] 2020-11-19 [RFC8973] Defined TXT keys: None
dots-call-home udp DOTS Signal Channel Call Home Protocol. The service name is used to construct the SRV service names "_dots-call-home._udp" and "_dots-call-home._tcp" for discovering Call Home DOTS clients used to establish DOTS signal channel call home. [IESG] [IETF_Chair] 2020-11-19 [RFC8973] Defined TXT keys: None
dots-data tcp DOTS Data Channel Protocol. The service name is used to construct the SRV service name "_dots-data._tcp" for discovering DOTS servers used to establish DOTS data channel. [IESG] [IETF_Chair] 2020-11-19 [RFC8973] Defined TXT keys: None
est-coaps udp EST over secure CoAP (EST-coaps) [Toerless_Eckert_3] [Toerless_Eckert_3] 2022-05-03 2022-05-04 [RFC9148]. Defined TXT keys: None
jnx-kcsync tcp jollys keychain cloud sync protocol [Patrick_Stein] [Patrick_Stein] 2011-10-24 Defined TXT keys: hash=<40hex characters> salt=<40hex characters> uuid=<40hex characters> Example: hash=5e7580598c0d7064d4fc79faaeb42585e1a675f8 salt=f0164cb3a0c3d7efe75abea8fda86d2d56c8dda9 uuid=db61dc092922252e45bbb264f59147138c7fd5fa
lobby Gobby [Gobby_0x539] [Gobby_0x539] Defined TXT keys: None
msrps tcp MSRP protocol over TLS 2014-04-25 [RFC4976] Defined TXT keys:
robustirc tcp Like ircu (RFC1459), but failure tolerant due to strong consistency among n>=3 servers [Michael_Stapelberg] [Michael_Stapelberg] 2015-01-07 Defined TXT keys: None
smimeca tcp Domain signing certificate for S/MIME keys [IESG] [John_Levine] 2016-07-26 [draft-bhjl-x509-srv-01] Defined TXT keys: None
wot tcp W3C WoT Thing Description or Directory [W3C_Web_of_Things_Working_Group] [Kazuyuki_Ashimura] 2022-11-22 2022-12-15

Defined TXT keys:

td: Absolute pathname of the Thing Description of the Thing or Thing Description of the Thing Description Directory.

type: Type of the Thing Description, i.e. "Thing" or "Directory". If omitted, the type is assumed to be Thing.

scheme: Scheme part of URL. One of the following values can be specified, with the standard registered URI interpretations [RFC7595]: http (HTTP over TCP),https (HTTP over TLS/TCP), coap+tcp (CoAP over TCP), or coaps+tcp (CoAP over TLS/TCP). If omitted, the scheme is assumed to be http.

wot udp W3C WoT Thing Description or Directory [W3C_Web_of_Things_Working_Group] [Kazuyuki_Ashimura] 2022-11-22 2022-12-15

Defined TXT keys:

td: Absolute pathname of the Thing Description of the Thing or Thing Description of the Thing Description Directory.

type: Type of the Thing Description, i.e. "Thing" or "Directory". If omitted, the type is assumed to be Thing.

scheme: Scheme part of URL. One of the following values can be specified, with the standard registered URI interpretations [RFC7595]: coap (CoAP over UDP), coaps CoAP over DTLS/UDP. If omitted, the scheme is assumed to be coap.

x-plane9 udp x-plane9 [Austin_Meyer] [Austin_Meyer] Defined TXT keys: None

Contact Information

ID Name Organization Contact URI Last Updated
[Austin_Meyer] Austin Meyer mailto:austin&x-plane.com
[Gobby_0x539] 0x539 dev group http://darcs.0x539.de/trac/obby/cgi-bin/trac.cgi
[IESG] IESG mailto:iesg&ietf.org
[IETF_Chair] IETF Chair IETF mailto:chair&ietf.org
[John_Levine] John Levine mailto:standards&taugh.com 2016-07-26
[Kazuyuki_Ashimura] Kazuyuki Ashimura mailto:ashimura&w3.org 2022-11-22
[Michael_Stapelberg] Michael Stapelberg mailto:michael+iana&stapelberg.ch 2015-01-07
[Patrick_Stein] Patrick Stein mailto:Patrick.Stein&jinx.eu 2011-10-24
[Toerless_Eckert_3] Toerless Eckert mailto:tte&cs.fau.de 2022-05-03
[W3C_Web_of_Things_Working_Group] W3C Web of Things Working Group mailto:team-wot&w3.org 2022-11-22