PROTOCOLS(5)               Linux Programmer's Manual              PROTOCOLS(5)

       protocols - protocols definition file

       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 IANA
       (Internet Assigned Numbers Authority).

       Each line is of the following format:

              protocol number aliases ...

       where the fields are delimited by spaces or tabs.  Empty lines are
       ignored.  If a line contains a hash mark (#), the hash mark and the
       part of the line following it are ignored.

       The field descriptions are:

              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.

              optional aliases for the protocol.

       This file might be distributed over a network using a network-wide
       naming service like Yellow Pages/NIS or BIND/Hesiod.

              The protocols definition file.

       This page is part of release 5.08 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

Linux                             2012-08-05                      PROTOCOLS(5)