Types of Ports

Ports are further divided into three categories:

• Well Known Port
• Registered port
• Dynamic Port

Well Known Port

• It is from the range 0 to 1023
• It is reserved for common and specifically used service
• It is used by some widely adopted protocols and services like HTTP(port 80), FTP(port 21), DNS(Port 53), SSH(port 22), etc…..

Registered Port

• It is from range 1024 to 49151
• These are used by applications or services that are not as common
• But it is used by those applications or services which require its specific port
• Organizations can ask IANA(Internet Assigned Number Authority) for any specific port number within this range

Dynamic Port

• It is from range 49152 to 65535
• It is also known as Ephemeral or Private Port
• It is used for those connections that are temporary or short-lived
• It is not registered or assigned and can be used by any process

Whenever any application in one computer sends data to another application of a different computer then it sends using IP Address and MAC Address but how does our computer know that this data is for a specific application and this data is sent by any specific application? There comes the concept of Port.

For instance, imagine your MAC Address or IP Address as the PIN code of the nearest Post Office and your house address as a Port. Whenever any parcel is sent to you it gets received by the nearest post office and then it is identified by your address where to deliver that parcel. Similarly in a computer data is first received using their IP or MAC address then it is delivered to the application whose port number is with the data packets.

Port is a logical address of a 16-bit unsigned integer that is allotted to every application on the computer that uses the internet to send or receive data.

Now every time any application sends any data, it is identified by the port that which the application sent that data and the data is to be transferred to the receiver application according to its port. We often call port as port number.

In the OSI Model ports are used in the Transport layer. In the headers of Transport layer protocols like TCP and UDP, we have a section to define port(port number). The network layer has to do nothing with ports, their protocols only care about IP Addresses.

Ports are assigned by computer i.e. operating system to different applications. Ports help computer to differentiate between incoming and outgoing traffic. Since the port is a 16-bit unsigned number it ranges from 0 to 65535.