protocols(4tcp)

protocols -- protocol name database

Synopsis

/etc/protocols

Description

The protocols file contains information regarding the known protocols used in the DARPA Internet.

Files

/var/yp/domainname/protocols.byname: Corresponding NIS map containing network protocols known to your network. The protocol name is the key in the map.
/var/yp/domainname/protocols.bynumber: Same as protocols.byname, except key is protocol number instead of protocol name.

Usage

The protocols file is used to initialize commands and protocols with reserved values.

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 appearing after the ``#'' are ignored.

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

When the Network Information Service (NIS) is in use, it references the NIS maps protocols.byname or protocols.bynumber on the NIS server instead of /etc/protocols.

Examples

The following is a sample data base:

   #
   # Internet (IP) protocols
   #
   ip	0	IP	# internet protocol, pseudo protocol number
   icmp	1	ICMP	# internet control message protocol
   ggp	3	GGP	# gateway-gateway protocol
   tcp	6	TCP	# transmission control protocol
   pup	12	PUP	# PARC universal packet protocol
   udp	17	UDP	# user datagram protocol

References

getprotoent(3N)

Notices

A name server should be used instead of a static file. A binary indexed file format should be available for fast access.