4.4BSD/etc/protocols

#
# Internet (IP) protocols
#
#	@(#)protocols	5.1 (Berkeley) 4/17/89
#
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