# protocols(5) - man - phpMan

[PROTOCOLS(5)](https://www.chedong.com/phpMan.php/man/PROTOCOLS/5/markdown)                          Linux Programmer's Manual                         [PROTOCOLS(5)](https://www.chedong.com/phpMan.php/man/PROTOCOLS/5/markdown)



## NAME
       protocols - 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  num‐
       bers 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 con‐
       tains a hash mark (#), the hash mark and the part of the line following it are ignored.

       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 network-wide naming service like Yellow
       Pages/NIS or BIND/Hesiod.

## FILES
       _/etc/protocols_
              The protocols definition file.

## SEE ALSO
       [**getprotoent**(3)](https://www.chedong.com/phpMan.php/man/getprotoent/3/markdown)

       ⟨<http://www.iana.org/assignments/protocol-numbers>⟩

## COLOPHON
       This  page  is  part  of  release  5.10 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 <https://www.kernel.org/doc/man-pages/>.



Linux                                        2012-08-05                                 [PROTOCOLS(5)](https://www.chedong.com/phpMan.php/man/PROTOCOLS/5/markdown)