HOWNOTTO: Set Up A Segregated Home Network.

If you want to know why I call myself The Brainwrecked Tech, here’s a good example of why. While browsing the net for information in creating my last article, I came across the book Wireless Network Hacks & Mods For Dummies. Someone got paid to come up with this! For the For Dummies series, no less! And they got it wrong! And here I sit, getting paid zilch to tell you how to do it right.

Bad Example of Network Segregation

Let’s think about how this set up works. Let’s call your section of the LAN, oh, LAN1? And let’s be equally inventive and call the LAN for your neighbors and friends LAN2.

You use one of the computers on LAN1 to make an unsolicited request to a web server like yahoo.com. LAN1’s router sees a computer on the LAN making a request to yahoo.com and stores a bit of information so that when yahoo.com replies, it know where to forward the information to. The router is not going to block the reply because it’s a solicited request.

Guess what? That’s exactly what going to happen on LAN2.

Someone uses their computer on LAN2 to make an unsolicited request to see a file share on your computer on LAN1. LAN2’s router sees a computer on the LAN making a request to your computer and stores a bit of information so that when your computer replies, it knows where to forward the information to. The second router is not going to block the reply because it’s a solicited request.

And the first router isn’t going to block the request because — tada! — you’ve made LAN2 part of LAN1.

Advertisements