Protocol

[root@www ~]# cat /etc/protocols | less
# /etc/protocols:
# $Id: protocols,v 1.9 2009/09/29 15:11:55 ovasik Exp $
#
# Internet (IP) protocols
#
#       from: @(#)protocols     5.1 (Berkeley) 4/17/89
#
# Updated for NetBSD based on RFC 1340, Assigned Numbers (July 1992).
# Last IANA update included dated 2009-06-18
#
# See also http://www.iana.org/assignments/protocol-numbers

ip      0       IP              # internet protocol, pseudo protocol number
hopopt  0       HOPOPT          # hop-by-hop options for ipv6
icmp    1       ICMP            # internet control message protocol
igmp    2       IGMP            # internet group management protocol
ggp     3       GGP             # gateway-gateway protocol
ipencap 4       IP-ENCAP        # IP encapsulated in IP (officially ``IP'')
st      5       ST              # ST datagram mode
tcp     6       TCP             # transmission control protocol
cbt     7       CBT             # CBT, Tony Ballardie <A.Ballardie@cs.ucl.ac.uk>
egp     8       EGP             # exterior gateway protocol
igp     9       IGP             # any private interior gateway (Cisco: for IGRP)

Linux裡的Internet (IP) protocols 只擷取一小段