Your new wireless home computer network could make you the target of a drive-by. A drive-by hacker, that is.

Hackers increasingly are cracking into wireless networks based on a standard called "Wi-Fi" (wireless fidelty), also known as 802.11b. Wi-Fi networks have taken off with both consumers and businesses because they're relatively inexpensive to install and transmit information at a speedy 11 megabits per second.

What's more, Wi-Fi networks broadcast data across distances of hundreds of feet and through walls, meaning that a hacker down the street can intercept Wi-Fi signals without being noticed.

Already hackers who want quick, free high-speed Internet connections cruise cities with laptops and antennas, connecting to corporate networks with inexpensive wireless PC cards, said Brad Powell, a computer security expert at Sun Microsystems in Palo Alto, Calif.

There is even a Web site, www.netstumbler.com, which has maps to streets where people can piggyback on wireless Internet networks run by companies such as 3COM and Lucent Technologies.

It's just a matter of time before unscrupulous people use wireless hacking techniques to steal financial and personal information or transmit viruses into home-based and corporate wireless networks, experts said.

"Is this a risk? Sure it is," said Tom Powledge, a product manager at Cupertino, Calif.-based Symantec who has a wireless network at home.

"I know my signals go through walls," he said. "I don't want my neighbor using my Internet or sniffing around (on my computer)."

Wi-Fi devices are the latest rage among consumers who want to free their computers and PC accessories from cable clutter. Americans bought $44.3 million worth of Wi-Fi devices during the first nine months of 2001, compared with just $5.5 million during the same period last year, according to NPD Intelect in Reston, Va.

Protecting your home wireless network from a potential hacker isn't difficult, the experts said. Often, it's as simple as enabling the WEP (Wireless Equivalent Privacy) settings built into wireless base stations and network cards. These settings can be activated from a software menu and prevent outsiders from gaining access to a wireless network, Powledge said.

Although a determined hacker still might be able to break through WEP, it would be very time consuming so this should provide adequate protection for home computer users, he said.

Another option is to install a firewall to block attacks by hackers, said Christopher Klaus, CEO of Internet Security Systems in Atlanta, Georgia. ISS (www.iss.net) advises companies on protecting their wireless networks and sells BlackICE Defender firewall software for around $40, Klaus said.

Symantec (www.symantec.com) and McAfee (www.mcafee.com) also sell firewalls for home users and businesses.