What is port forwarding?

Port forwarding allows external devices to connect to devices in a private network.

The need for port forwarding

Small networks (e.g., home networks) have a single external IP address, and each device in the network has a unique internal IP address. Internal IP addresses are not routable on the internet; hence, a router uses Network Address Translation (NAT) to map internal IP addresses and port numbers to external IP addresses and port numbers. The port numbers that NAT uses are randomly selected, which poses a problem when you want a host to connect to a server in your internal network that uses a standard port.

How port forwarding works

Suppose you have a web server running on your private network ​and external clients expect to connect to port 80. To enable this, you need to use port forwarding. In this example, port forwarding would involve statically mapping the external IP address and port 80 to the internal IP address and port 80.

How to enable port forwarding

To enable port forwarding, log in as an admin on the desired router, and enter the external port numbers that need to be mapped to the internal port number.