PROTOCOLS(5)

NAME
protocols - the protocols definition file

DESCRIPTION
This file is a plain ASCII file, describing the various DARPA internet protocols that are available from the TCP/IP subsystem. It should be consulted instead of using the numbers in the ARPA include files, or, even worse, just guessing them. These numbers will occur in the protocol field of any ip header. Keep this file untouched since changes would result in incorrect ip packages. Protocol numbers and names are specified by the DDN Network Information Center. Each line is of the following format:
    protocol number aliases ...
where the fields are delimited by spaces or tabs. Empty lines and lines starting with a hash mark (#) are ignored. Remainder of lines are also ignored from the occurrence of a hash mark. The field descriptions are:

protocol
    the native name for the protocol. For example ip, tcp or udp.

number
    the official number for this protocol as it will appear within the ip header.

aliases
    optional aliases for the protocol.

This file might be distributed over a network using a networkwide naming service like Yellow Pages/NIS or BIND/Hesoid.

FILES

/etc/protocols
    The protocols definition file.

SEE ALSO
getprotoent(3) Guide to Yellow Pages Service Guide to BIND/Hesiod Service