GigaFast Ethernet
Appendix A
A
ppendix A: TCP/IP
Well-Known Port
Any application or process that uses TCP for its transport is assigned a
unique identification number called a TCP port. TCP ports specify the path
of communications between client and server applications. These ports are
numbered beginning with zero. Port numbers for client applications are
dynamically assigned by the operating system when there is a request for
service. Port numbers for server applications are pre-assigned by the
Internet Assigned Numbers Authority (IANA) and do not change. The
following is a short list of some well-known port numbers.
Table 0-1 Well-Known TCP ports
Port No.
Name (TCP)
Description
20
FTP-DATA
FTP (data)
21
FTP
FTP (command)
23
TELNET
Terminal Connection
25
SMTP
SMTP
53
DOMAIN Name
Domain Name Server
79
FINGER
Finger
80
HTTP
Web
110
POP3
POP3
113
AUTH
Authentication Service
139
NETBIOS-SSN
NETBIOS Session Service
1723
PPTP
Point to Point Tunneling Protocol
