What Is Port Forwarding?

Date First Published: 15th May 2022

Topic: Computer Networking

Subtopic: Network Services

Article Type: Computer Terms & Definitions

Difficulty Level: 9/10

Learn more about what port forwarding is in this article.

Port forwarding, also known as port mapping enables computers over the internet to connect to a network that is outside of the router or firewall of their network and transmit incoming communication of a specific port to the same port on an internal network device. It is a method of making a computer accessible over the internet even when they are behind a router and it redirects a communication request from one IP address and port number to another.

Examples Of Port Forwarding

Someone needs to remotely control their computer from their home through the use of a remote desktop connection. Once connected to the remote computer, it is possible for the files and programs of that computer to be accessed in a similar way to if it was directly being used. Then, the request will be sent with the IP address of the other computer with a port number, such as ‘172.64.35.196:3389’. The ‘3389’ at the end of the IP address is the port number for Remote Desktop and Microsoft Terminal Services.

The request with the port number will then flow through the internet to the router. Once it reaches the router, it then needs to know where to forward the request for port 3389. If port forwarding was not configured, it would be impossible for them to connect to the computer. This is because the router would not know how to handle the request. Port forwarding will work by the router being configured to forward any requests that arrive with a specific port, such as port 3389 and send the request to the computer.

Note:

A port is a 16-bit unique number that identifies a specific process or type of network service. IP addresses use the port number to determine what the purpose is, such as using FTP, HTTP, email, or remote desktop. Port numbers are always associated with an IP address and a process.

How To Set Up Port Forwarding?

Port forwarding can be set up by going to the configuration page of the router, which can be visited by entering the internal IP address of the router into a web browser. In Command Prompt, this can be performed by running it as administrator, typing ‘ipconfig’ and then looking for the ‘default gateway’ property, which is the internal IP address of the router. Also, the ‘IPv4 address’ property needs to be entered into the configuration page of the router, which is the IP address of the computer.

Then, once the configuration page has successfully loaded, go to the ‘port forwarding’ section, enter a name for the application, enter the remote desktop connection port number as the internal and external port, and then point it to the IP address of the computer that needs to be remotely accessed. Once the enabled box is ticked and the settings are saved, the port forwarding has successfully been configured.

Now, when a request is sent to the computer that wants to remotely connect with port 3389, the router will then know where to forward the request and the connection is established. The port forwarding entries simply tell the router to direct that traffic to an alternative location if it is encountered.