/etc/protocols——三层协议号—— RFC
1340
[root@nm mac]# cat /etc/protocols
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
......
/etc/services——RFC
1700
四层端口号
[root@nm mac]# cat /etc/services | more
# service-name port/protocol
[aliases ...] [# comment]
echo
7/tcp
echo
7/udp
discard
9/tcp
sink null
discard
9/udp
sink null
daytime
13/tcp
ftp-data
20/tcp
ftp-data
20/udp