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Let’s say your home computer is nearly always on and connected to the Internet, but you’re not always at home to use it. And you’re now at work or on a business trip, and you’d like to contact your computer at home. Perhaps you need to run a special program on it, or maybe upload a needed file, or you just want to look through your webcam and check on your cat. There are a lot of things you need to do in order to remotely access your home computer, and one of the first is to figure out your home network’s Internet address.

 

To do this, you could – before leaving home – go to What is My IP and write down the address it gives you. The folks at that website will give you your “public” IP address, which is the address that your home router uses to identify itself to the world. This address will appear as four numbers separated by a dot. For example, 96.247.87.34. When you’re away from home, you can then access your home network at that address. Ignoring for the moment that your home router may not let you in the door, you should be able to contact your PC.

 

But there’s a problem . . .

 

Your public IP address can change at any moment without warning. Why? Your home service provider may change your router’s public IP address periodically to free up certain numerical ranges of addresses and use them for some other purpose. Your home router is cool with that; through something called “DHCP” (Dynamic Host Control Protocol), your router will change its address to whatever value it is given by your service provider. But if you’re on the road and you use the specific address that you previously wrote down to access your home network, your home router will no longer respond to that address. You may instead find yourself inadvertently trying to hack into someone else’s network, because your old address was reassigned.

 

A good way to solve this problem is to have your home computer periodically check in with an online service. During this “check-in” process, the online service will make a note of your home computer’s public IP address. If your home service provider changes your public IP address, the service will thus be updated automatically. Then, when you’re on the road, instead of trying to contact your home network directly, you first contact the online service and get your latest home IP address. Afterwards, you can then contact your home network and be confident that even though the address may have changed, you have the latest copy.

 

The good news is that the service is free! It’s called Dynamic Network Services, Inc. Though they do charge for some of the more advanced services, the basic service is free. They even give you the software that you can load onto your home computer to cause it to check-in with the online service and update its address.

 

As I mentioned earlier, I ignored the fact that your home router will most likely not let you in the door. That is, your router will see you trying to contact it, and because it does not know who you are, it will assume that you’re trying to attack the network, and it will ignore you. Getting around this problem is beyond the context of this blog post; but suffice it to say for now that you can implement a Virtual Private Network (VPN) on your home router so that it allows you access only after it has authenticated you. If you are interested, I have lots of experience in this area, so if you leave a comment here, I’ll write an article detailing how to do it.

Best,

Dan

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