protocols

早期freebsd实现

#
# Internet (IP) protocols
#
#	@(#)protocols	8.1 (Berkeley) 6/9/93
#
ip	0	IP		# internet protocol, pseudo protocol number
icmp	1	ICMP		# internet control message protocol
igmp	2	IGMP		# internet group management 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 data protocol
iso-tp4	29	ISO-TP4		# ISO Transport Protocol Class 4
iso-ip	80	ISO-IP		# ISO Internet Protocol
encap	98	ENCAP		# RFC1241 encapsulation