Port Forwarding Basics – A Beginners Guide

Difficulty: 3

I thought this picture was bad. There are plenty worse ones available.Port Forwarding allows you to access computers behind a router, for various services. To put it another way, Port Forwarding offers you access to computers on your home network accessible from anywhere.

Eg, You may want to setup one of your home computers as a web server. If you have not set up port forwarding, typing in your home IP address into a browser will bring up the router settings. You will need to setup your router to send webpage requests to the computer that will be hosting the site. This is known as port forwarding and it is a supported feature for most routers. Without port forwarding you can’t move beyond the router, restricting you access to all of the computers on the network. 

I have found over the years, my needs for port forwarding have been limited to only a few simple tasks. I set up a web server and an ftp server on one machine. I also needed to have access to a remote desktop connection from another machine. This was easy to setup and allowed me to take my home computers with me on the road.

Once you have access to remote desktop on one machine, you have freedom to access shared network drives from within your home network. There is nothing that you are unable to access. It is as if you were at home, on your home computer.

This article will show you how to configure your router so that you can access computers on your home network, from any computer that is outside of your network. This article is designed for newcomers to Port Forwarding, meaning that there is lots of technical stuff left out.

Port Forwarding can get much more complicated than this article will go into, but we are only going to cover a few common tasks, and show the benefits you may receive by setting this up.

Some of these features, accessing your files in particular, can be done by setting up a Virtual Private Network(VPN). A VPN allows you to access a remote network, and treat you as if you are a member of that network. This is much more difficult to setup and it is more frustrating to use, though there are some security benefits in using a VPN. I find that port forwarding is an easier option in most circumstances and it is fairly safe and reliable if setup correctly.

There are a lot of various ports that you can open up for online gaming. This will not be covered in this article. If you find that you are having trouble with a particular peice of software accessing the internet, there is a good chance that you will need to setup port forwarding. This is particularly common with some older messaging programs and networked games.

Port Table: A list of common ports

Each type of network data you want to access, uses a different port number. This is what allows us to request the ports of a particular computer, to access the service on that computer. It is not possible to access the same port on two computers, though it is sometimes possible to configure your router and computer to use a different port for a service. Eg. You can only access remote desktop from one computer while you are not on the local network.

Below is a list of some common ports you may want to configure.

80: HTTP, this service is what you will want to set if you setup a web server.
21: FTP, this service is used for transferring files over a network, FTP server.
3389: RDP, this service is for accessing computers via remote desktop.

The list of ports is very lengthly, but I cannot see them being used for general use. They are all for specific programs. Portforward.com has a comprehensive list of ports.

Setting up your router

There is a good chance that your router will have a Port Forwarding section in the routers settings. All you need to do it select the service you want access to, such as RDP, enter in the port it uses(3389), and then enter in the IP address of the machine that you want to offer this service. Eg. Open a command prompt and type in “ipconfig” to find out yours.

You will need to configure you server to offer the service itself, Eg. Enable Remote Desktop Connection in Windows. 

Know your IP address

So that you can access your home network while you are on the road, you will need to know your home networks IP. This will not start with 10 or 192, we are after the address of your modem. If you have a static IP, you can memorise it and plug it into whatever program accesses the services you have setup.

Most people have a dynamic IP which changes every day/month/year. This makes it very hard to remember. If this is the case for you, please check out DynDNS. DynDNS allows you to use real words instead of an IP address. Your router or a desktop client will update their servers automatically, so you will never have to remember your home IP again.


If all of this is a bit too much, check out portforward.com. They have a facility in which you can select your router from an extensive list, choose which port to forward by name, and then they will show you exactly how to do it.

I hope you have enjoyed this article and found it useful. Please stick around and check out some other articles at Inspect My Gadget.

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2 comments so far »

  1. Peter said, on February 19, 2012 @ 1:06 am

    I am confused. Why we do not use MAC address instead of IP address? Is the MAC address a unique one to identify a computer?

  2. Chris Duckworth said, on February 19, 2012 @ 10:02 am

    Yep, that’s right. Mac addresses are unique. A computer doesn’t have an IP address until it has been allocated one by the network, or taken from settings in the OS. i.e. There is no IP address until after startup, where a mac address is built into the hardware.

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