Port Forwarding 101

A simple explanation of what port forwarding is, and why it is useful.

Maybe you’re a gamer. Maybe you might be running your own server. I’m not sure what led you to this tutorial, but if you follow these steps correctly, you will not only be able to set up your proper port forwarding rules in the next few minutes, you will be able to learn how to forward ports for any application you come across that requires connectivity to the internet.

For starters, let me explain port forwarding in nice plain english, that you might understand the concept of what we are going to be doing here. Port forwarding is the process of opening a hole in your router to allow internet traffic to pass through it and to your computer with no interfence. When you are connected to the internet directly (modem to computer) you are fully exposed to the glory – and wrath – of the online world. If you are part of a network, your router will not only act as a buffer between your computer and that dangerous thing that we are so addicted to, but it will also allow you to pass files and information back and forth between other machines on the same router.

Now that you have an idea of what port forwarding is, why should you use it? Many programs these days will automatically set themselves up to play nicely with your router, but they won’t tell you why. On most networks, all machines connected to the router will use the same IP address to connect to the internet. This is call Network Address Translation, and there are a number of reasons this is useful, but at the same time, it can confuse a lot of internet traffic. Now for example, let’s say your using Limewire and you’re trying to download a song. When you start downloading the song you want, the various sources the song is coming from will attempt to connect to your computer to give you your requested file. As I explained above though, if you have more then one computer on your network, you all use the same IP address, and that could make it hard for Limewire to know which computer to pass the song to. So we use port forwarding to tell it that certain programs go to certain places on the internal network. By doing so, Limewire will connect to your IP address, which will redirect to your router, which in turn consults your port forwarding to see which internal machine to redirect to.

If you are reading this on a computer running Windows XP or newer, you probably don’t need to do any manual port forwarding, since Microsoft introduced uPnP, applications can access your router and make changes automatically. If you are not using a newer version of Windows, or the application you are running does not support uPnP, then it is time to roll up your sleeves and poke around inside your router a little. I cannot give you exact instructions, as most routers are different, but I can give you a great website to help you with the specifics beyond what I can explain here. Just pick the model of your router off this list http://www.portforward.com/english/routers/port_forwarding/routerindex.htm and follow the instructions it gives you. Make sure you note what it tells you your IP address is, up near the top of the page.

If you are unsure as to what the model of router you own, take a look at it. 9 times out of 10, somewhere on the router, there will be the manufacturer, model, serial number, and quite often the MAC address as well. We don’t need all that right now, but it’s a good thing to know should it come up later down the road. If you do not have physical access to your router, talk with your network admin, as they will probably set up port forwarding for you.

Thats it. A quick and painless explanation of what port forwarding is and why to use it. If you still have a hard time figuring anything out, drop a comment and I’ll try and help.

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