Wireless Network Security

Wireless networks are all the rage. But do you know how to protect your data from eavesdropping hackers?

By Simson Garfinkel

January 09, 2003 — CSO — You've read a lot about the security of wireless LANs, or WLANs, during the past year. With the plummeting prices of wireless access points and laptop cards, businesses, schools and home users have all rushed out and installed low-cost WLANs. Most of these systems are easy to install, and as it turns out, most wireless access points have their access control disabled. This is great for useability: If you can receive the radio signal, you can put your laptop on the network without setting any codes or entering any encryption keys.

But that also means that many homes and businesses have inadvertently opened their network to outsiders because radio waves can travel through walls, out onto the street and even into your neighbor's house. And you thought the British Royal Family had problems.

Because of those WLAN vulnerabilities, "war driving" has become a popular hacker pastime. All you need is a wireless card, a laptop, a global positioning system receiver connected to your laptop, a car and a free afternoon. Drive around town with a copy of NetStumbler or a similar program running, and your computer will log the geographical position of any WLAN it finds. When you're done, you can graph the results on your computer. You can even upload the findings to one of the national databanks. Or, if you feel especially motivated, you can get out of your car and mark the area so that other nosy strangers can find ita kind of hacker public-service ritual known as war chalking.

Although war driving started as an exercise in demonstrating computer security holes, most people involved these days have a different political agenda. They're interested in using WLANs to create a mesh of free wireless Internet service throughout our neighborhoods. The war driving maps show where coverage is good and where new coverage needs to be added.

I'm all in favor of community groups, businesses and individuals teaming together to provide free high-speed wireless Internet access. Indeed, I have opened up the wireless access point in my own house; if you stand in my driveway with your wireless-enabled PDA, you can browse the Internet using my connection without even knocking on the door. Likewise, I've come to expect that high-speed Internet access will be available at conferences that I attendand in most cases, it's both easier and cheaper for conference organizers to set up a single wireless hub than to set up an Ethernet switch and string a lot of Category-5 cables.

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