Open System Services Shell and Utilities Reference Manual (G06.28+, H06.05+)

File Format Reference Pages protocols(4)
NAME
protocols -Defines the Internet protocols used on the local host
DESCRIPTION
The /etc/protocols file contains information about the known protocols used in the DARPA
(Defense Advanced Research Projects Agency) Internet. Each protocol is represented by a sin-
gle line in the protocols file. Each entry is of the following form:
name number aliases
The fields contain the following information:
name Official Internet protocol name.
number Protocol number.
aliases Unofficial names used for the protocol.
Items on a line are separated by one or more spaces or tab characters. Comments begin with the
# (number sign), and routines that search the protocols file do not interpret characters from the
beginning of a comment to the end of the line. A protocol name can contain any printable char-
acter except a field delimiter, newline character, or comment character (#).
EXAMPLES
Example lines from a protocols file are shown below:
#
# Internet (IP) protocols
# @(#)protocols 5.1 (Berkeley) 4/17/92
#
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
egp 8 EGP # exterior gateway protocol
pup 12 PUP # PARC universal packet protocol
udp 17 UDP # user datagram protocol
hmp 20 HMP # host monitoring protocol
xns-idp 22 XNS-IDP # Xerox NS IDP
rdp 27 RDP # "reliable datagram" protocol
FILES
/etc/protocols Specifies the pathname of the file.
RELATED INFORMATION
Functions: endprotoent(3), getprotobyname(3), getprotobynumber(3), getprotoent(3), set-
protoent(3).
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