Chapter 3 Configuration
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 | Protocol | Description |
Number | | |
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) |