What is Port Number in Computer?

In this tutorial, we are going to see What is port number in computer? Many TCP/IP programs can be run simultaneously on the Internet (for example, you can open several browsers simultaneously or browse HTML pages while downloading a file via FTP). Each of these programs works with a protocol, but the computer must be able to distinguish between the different data sources.

So, to facilitate this process, each of these applications is assigned a unique address on the machine, coded on 16 bits: a port (the combination IP address + port is then a unique address in the world, it is called socket).

The IP address is therefore used to uniquely identify a computer on the network, while the port number indicates the application for which the data is intended. In this way, when the computer receives information intended for a port, the data is sent to the corresponding application. If it is a request to the application, the application is called the server application. If it is a response, it is called a client application.
 

 

Types of Ports in Networking – Default port assignments:

There are thousands of ports (these are coded on 16 bits, so there are 65536 possibilities), that’s why a standard assignment has been developed by the IANA (Internet Assigned Numbers Authority), in order to help in the configuration of networks.

• Ports from 0 to 1023 are the “Well Known Ports”. They are generally reserved for system processes (daemons) or programs run by privileged users. A network administrator can, however, bind services to the ports of his choice.
• Ports from 1024 to 49151 are called “Registered Ports”.
• Ports from 49152 to 65535 are called Dynamic and/or Private Ports.

Here are some of the most commonly used recognized ports:

Port	Service or Application
21	FTP
23	Telnet
25	SMTP
53	DNS
22	SSH
143	IMAP
80	HTTP
443	HTTPS
110	POP3
119	NNTP

 
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