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PROTOCOLS(5) File Formats Manual PROTOCOLS(5)

protocolsprotocol name data base

The protocols file contains information regarding the assigned protocol numbers used by IPv4 and IPv6 to identify the next level protocol. For each protocol a single line should be present with the following information:

official protocol name
protocol number
aliases

Items are separated by any number of blanks and/or tab characters. A ``#'' indicates the beginning of a comment; characters up to the end of the line are not interpreted by routines which search the file.

Protocol names may contain any printable character other than a field delimiter, newline, or comment character.

/etc/protocols
The protocols file resides in /etc.

getprotoent(3)

IANA Allocation Guidelines For Values In the Internet Protocol and Related Headers, RFC 2780, March 2000.

IANA Allocation Guidelines for the Protocol Field, RFC 5237, February 2008.

The protocols file format appeared in 4.2BSD, describing the "known protocols used in the DARPA Internet".

A name server should be used instead of a static file.

December 7, 2020 dev