Part five of our six steps in securing your wireless network is very straight forward.  If you've taken every possible step to keep out wireless intruders, there's still a chance that someone can get onto your network. So you should regularly check to see whether someone's where he shouldn't be - on your network.

Normally, when your computer connects to your network, your router gives it an IP address. Every computer connected to the Internet needs an IP address in order to browse the Web.

Most times, your router just hands out these IP addresses without question to all network clients, so any time a nearby wireless PC asks for an IP address, the router hands one over with no questions asked.

Every piece of networking hardware has a unique ID number, like a serial number, called a MAC address. No two pieces of networking hardware have the same MAC address. A MAC address always has 12 hexadecimal digits and looks something like this: 00-08-A1-0B-8E-3D.

You can use these MAC addresses to keep out intruders. Many routers let you permit only certain MAC addresses onto your network. You can set your router to let in each of your computers, and keep everyone else out.

It's simple: You need to use encryption. Encryption keeps you safe in two ways. First, it won't allow anyone onto your network who doesn't have the special pass key, so it's a way to make sure that intruders can't get it. It also stops snoopers as well, because anyone who tries to sniff out network activity will only see garbled, meaningless characters, rather than your email, for example.

There are two encryption standards you can use to protect your network: Wireless Equivalent Protocol (WEP) and Wi-Fi Protected Access (WPA).