Service Name and Transport Protocol Port Number Registry

Last Updated

2026-10-09

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

[RFC 6335]

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 basis, as described in [RFC 6335].

Port numbers are divided into three ranges, with their uses and assignment procedures specified in [Section 8.1.2 of RFC 6335]:

- System Ports (0-1023) are assigned using the [IETF Review] or [IESG Approval] procedures.
- User Ports (1024-49151) are assigned using the [IETF Review], [IESG Approval], or [Expert Review] procedures.
- Dynamic and/or Private Ports (49152-65535) are not assigned.

The registration procedures for service names and port numbers are specified in [RFC 6335], while the registration policies referenced above are defined in [RFC 8126].

Assigned ports both System and User ports SHOULD NOT be used without or prior to IANA registration.

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.

Registration Forms

- To request a new assignment, please use the [Application for Service Names and User Port Numbers] form.
- To modify an existing assignment, please use the [Modify a Port Number Assignment] form.

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