Port Forwarding Explained

Port Forwarding is a method of controlling the flow of data to and fro from a computer connected to the Internet. Forwarding is opening up of computer networking ports for data inflow or outflow through a firewall or router configuration. Most operating systems have a built in firewall that controls the access rights to your computer. Akin to trade ports in the real world, the communication on the Internet is handled through ports which are devoted to various Internet protocols.

A computer port is a software construct which serves as a communication portal for a particular application and Internet protocol. Every service offered on the Internet is through a numbered port which is specifically devoted to it. Forwarding ports is instructing the firewall software to open certain ports for communication. For example web site pages are routed to your computer through port number 80 and it is devoted to the Hypertext Text Transfer Protocol (HTTP). On the other hand, File Transfer Protocol (FTP) based data traffic is routed through port number 21. The rule is that one port can only be used for one program at a time.

What is it used for?

There are many applications of this facility. It may be that you have a network of computers connected to the Internet and you want specific data routed only to a specific computer. In such a case too, forwarding allows you to open specific ports on the network for communication by configuring the network router. Be it simple or wireless forwarding, the basic idea remains the same. Specific ports are configured for routing of specific data packets.

Forwarding makes division of work among allied web servers possible by assigning separate ports for each job. For example a web server may be hosting a site and there may be another server for handling requests for online games. Through forwarding, game requests are routed to the game server, while web page requests are routed to the web server. This is how workload is divided and efficiency of a site is enhanced.

It also secures your computer from unauthorized external accesses by allowing access through only specific ports. It can also speed up routing of data as less time is wasted in determining the destination of data being transferred when the data packets arrive at the router. Web proxy servers use it to make sure that there is no direct connection between the client computer and Internet. It also helps in protecting the client from unauthorized external access to its resources. Forwarding can be effectively used to conduct web TCP traffic through secure SSH (Secure Shell) connections. This enables the encryption of web traffic through secure SSH tunnels.

This explanation has only touched the bare essentials of the subject. To know its implementation, you must study data routing on the Internet quite deeply. One way of forwarding ports on your home computer is opening ports through your firewall for communication.