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Chapter 3 Configuration
63
3.6.3.6 Virtual Server
In TCP/IP and UDP networks, a port is a 16-bit number, used by the host-to-host
protocol to identify to which application program it must deliver incoming messages.
Some ports have numbers that are pre-assigned to them by the IANA, and these are
known as well-known ports. Servers follow the well-know port assignments so clients
can locate them.
The Internet Assigned Numbers Authority (IANA) is the central coordinator for the
assignment of unique parameter values for Internet protocols. Port numbers range from
0 to 65536, but only ports numbers 0 to 1024 are reserved for privileged services and
designated as well-known ports. The registered ports are numbered from 1024 through
49151. The remaining ports, referred to as dynamic ports or private ports, are numbered
from 49152 through 65535.
Examples of well-known and registered port numbers are as below, for further
information, please see IANA web, http://www.iana.org/assignments/port-numbers.
Port
Number
Protocol Description
1 ICMP PING
20 TCP FTP Data
21 TCP FTP Control
22 TCP & UDP SSH Remote Login Protocol
23 TCP Telnet
25 TCP SMTP (Simple Mail Transfer Protocol)