文档介绍：Port Assignments:
Keyword Decimal Description References
------- ------- -rs
# Jon Postel <postel&>
# 12/tcp Unassigned
# 12/udp Unassigned
daytime 13/tcp Daytime (RFC 867)
daytime 13/udp Daytime (RFC 867)
# Jon Postel <postel&>
# 14/tcp Unassigned
# 14/udp Unassigned
# 15/tcp Unassigned [was netstat]
# 15/udp Unassigned
# 16/tcp Unassigned
# 16/udp Unassigned
qotd 17/tcp Quote of the Day
qotd 17/udp Quote of the Day
# Jon Postel <postel&>
msp 18/tcp Message Send Protocol
msp 18/udp Message Send Protocol
# Rina Nethaniel <---none--->
chargen 19/tcp Character Generator
chargen 19/udp Character Generator
ftp-data 20/tcp File Transfer [Default Data]
ftp-data 20/udp File Transfer [Default Data]
# Jon Postel <postel&>
ftp-data 20/sctp FTP
# IETF TSVWG
# Randall Stewart <rrs&>
# [RFC4960]
ftp 21/tcp File Transfer [Control]
ftp 21/udp File Transfer [Control]
# Jon Postel <postel&>
ftp 21/sctp FTP
# IETF TSVWG
# Randall Stewart <rrs&>
# [RFC4960]
ssh 22/tcp The Secure Shell (SSH) Protocol
ssh 22/udp The Secure Shell (SSH) Protocol
# [RFC4251]
ssh 22/sctp SSH
# IETF TSVWG
# Randall Stewart <r