Network Ports

Ports are used for communication between computers.
If the analogy where an IP address is equal to a building's street address, ports can be thought of as telephone numbers which go into that specific 'building'. However, each 'building' has its own set of numbers (ports) which may not apply elsewhere.

Port Ranges

Ports are divided into specific ranges:

• 0-1023 are 'Well Known Ports' and are used for many well established protocols.
• 1024-49151 are 'Registered Ports' where other applications can officially register ports for a specific use.
• 49152-65535 are 'Dynamic Ports' and are generally not used for any public application.

Common Ports

Often, ports can be used to determine what kind of application is running or listening on a specific port. Here is a list of commonly used ports on the Internet. It is impossible to list every single use for a port since applications are not always registered. The IANA handles the registration of ports, and most of the data in the following table is sourced from the official assignments.