How to protect your wireless network

Preston Gralla provides step-by-step instructions

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In Windows Vista:

1. Select Control Panel --> Network and Internet --> Network and Sharing Center --> View Status.

2. From the Security type drop-down box, select WPA-Personal or WPA2-Personal, depending on your encryption method.

3. From the Encryption type drop-down box, select TKIP. In the Network security key box, type in the security key you used on your router.

4. Click OK. Your Windows Vista PC can now connect using encryption.

Configuring WPA encryption on a wireless PC in Windows Vista
Configuring WPA encryption on a wireless PC in Windows Vista. (Click image to see larger view)

If you've got a small or medium-size business, and are looking to encrypt your network, you might consider an outsourced solution, such as SecureMyWiFi from WiTopia. Prices for SecureMyWiFi vary according to your network size, and start at $99 per year for one wireless access point with 100 users.

Protect yourself using MAC addresses

There's another way to protect your wireless network: Tell it to allow only certain computers to connect, and ban all others. To do that, you'll filter by Media Access Control (MAC) addresses, which are in essence IDs for wireless adapters. Every piece of networking hardware has a unique MAC address. So you'll be able to tell your router to allow only specific MAC addresses onto the network and keep all others off.

First, you need to find out the MAC address of all of the wireless adapters on your PCs.

1. Open a command prompt on each computer, type ipconfig /all, and press Enter.

2. The screen that appears will display a good deal of information. Look for the numbers next to Physical Address, such as 00-08-A1-00-9F-32. That's the MAC address. Write all those MAC addresses on a piece of paper.

Now log back into your router, and configure MAC address filtering. On the Linksys WRT54GX4 router:

Protecting your network by only allowing PCs with certain MAC addresses from connecting
Protecting your network by allowing only PCs with certain MAC addresses to connect. (Click image to see larger view)

1. Click Wireless, and then click Wireless Network Access to get to the Wireless Network Access screen.

2. Select "Permit only," and type in the MAC addresses into the text boxes. Click "Save settings." Now, only computers you specify will be allowed onto your network.

Turn off your network when you're not using it

This simple precaution can go a very long way toward keeping you safe: Simply turn off your router when you're not using your network. If you're off at work all day and no one's home, why keep your router running? The same holds true for when you sleep, or are away from your house for another reason. The less time your wireless network is available, the less likely it is to get hacked.

Check for wireless intruders

You can never be too safe, and so even if you've taken all this advice, it's a good idea to check your network to see if intruders have made their way in. And if you haven't taken all this advice, that's all the more reason to check.

In the next part of this two-part article, I'll show you how you can check your network to see whether any intruders have managed to worm their way in.

Editor's note: Do wireless nets really pose that much of a security threat? Computerworld editors Preston Gralla and David Ramel take opposing views on this question in a Sound Off. Read Preston's "Why you need wireless protection" and David's "Why worry about wireless?" and then then weigh in on the issue with your comments and in our QuickPoll.

Preston Gralla is a contributing editor to and the author of more than 35 books, including How the Internet Works, (Que, 2006).

Copyright © 2007 IDG Communications, Inc.

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