By Kim Komando
Gannett News Service

Wi-Fi is a popular way to network home computers. It's relatively inexpensive, convenient and fairly easy to set up. But most users don't take the extra step to lock it down. This can be a serious mistake.

Wi-Fi uses radio waves to transmit information. These waves are broadcast beyond the walls of your home and apartment, where they can be intercepted by anyone else with a wireless connection - including hackers.

Hackers take advantage of unsecured Wi-Fi networks. Some, who are called war drivers, drive around neighborhoods looking for open networks. Some are just keeping score, but others may attempt to access your personal data.

These steps can help you keep your home network and personal information secure.

• Stop broadcasting to the world. By default, most access points send a short message repeating the network's name. The network's name is called the SSID (Service Set Identifier). Anybody who lives (or drives) nearby can easily detect that you have a wireless network, find its name and jump on. By disabling the SSID broadcast, you are no longer telling the neighborhood that you have a wireless network.

Additionally, rename the SSID. Don't use your name or something easily identifiable.

• Change the password on your access point. Default passwords, which are often published as part of access point instruction manuals, are common knowledge. If unchanged, it takes only minutes to figure out the proper password.

When you change the password, make sure you use a combination of numbers and letters. The most secure are alphanumeric combinations, such as 3nO7tY5.

• Use encryption. There are two standards of encryption. Wired Equivalent Privacy (WEP) is an older, less secure method. It uses a constant 64- or 128-bit key that should deter all but the most experienced hackers.

Wi-Fi Protected Access (WPA) uses 256-bit encryption, which is much harder to decode. WPA also generates dynamic, or constantly changing, encryption keys. By the time a hacker breaks one key, a new one will have taken its place, effectively shutting down the hacker.

Even if you have old equipment, you may be able to get WPA through a firmware update. Firmware is software written on a chip inside a piece of hardware. Check your manufacturer's Web site.

Encryption does have a downside. It can slow your network, but that is preferable to a lack of security.

• Enable Media Access Control (MAC) filtering. Media Access Control is an address assigned to each wireless card. All wireless devices have unique MAC addresses. The address includes six sets of paired characters and is usually printed on the back of your wireless card.

MAC filtering tells your access point to grant access only to MAC addresses you enter.

You can do your own security check after implementing these measures. Install the free program NetStumbler (www.netstumbler.com) onto a laptop or personal digital assistant. This program will detect open Wi-Fi networks. After installing the program, walk around the outside of your house with your laptop or hand-held to see what a hacker might see. If your network is secure, NetStumbler shouldn't detect anything.

A determined hacker can eventually break down any security walls. But by taking preventive measures, you can make it difficult. Probably, the hacker will just move on.

With reporting by Ted Rybka