Sharing high-speed Internet access via wireless networks is growing in popularity, but some liken it to stealing cable TV.

Across the United States, community-based wireless networks are springing up aimed at giving the public anytime, anywhere Internet access.

One prominent example is in New York, where NYCWireless has created about 25 free access "nodes" for New Yorkers on the go. Co-founder Anthony Townsend, an urban planner, says his group has purely altruistic motives.

"It's a very loosely knit group of individuals that are interested in giving something back to the community that they live in," Townsend said. "So, by sharing out their broadband connection with their people in their neighborhood, they feel that they're providing a public good."

The goal is to use inexpensive, existing technologies -- primarily 802.11b, or Wi-Fi -- to get the public online. NYCWireless members purchase a business-grade DSL or cable modem connection (about $60 per month), which is then linked to wireless gateways like Apple's AirPort or Lucent's OriNoco (about $200). In return, co-op members are essentially able to operate a personal CLEC (competitive local exchange carrier) at no cost to the public (though donations are certainly welcomed).

Nearly 3,000 miles away at San Francisco State University, professor Sameer Verma is marrying Wi-Fi to cheap, unconventional equipment in order to link students to the business school's Ethernet.

"We used to have access through Ricochet, but once they stopped, we didn't have any other option, other than using dialup," Verma said. "And we figured we could probably connect these two buildings using wireless with just a point-to-point connection, but it needs an antenna to extend it that far."

His solution? Pringles potato chip cans, which he's testing as portable antennas. He found the blueprints on a website touting the wonders of Wi-Fi as an easy fix for those who want to be online everywhere.

Still, it's far from flawless technology. Distance and landscaping can degrade Wi-Fi signals. The spectrum also is subject to interference from devices like microwave ovens or cordless phones.

Then there's the lack of security mechanisms.

"These networks are wide-open, and these platforms can be used for all kinds of illicit activities," Townsend said. "So we've been developing some software solutions to help people detect if, say, some denial-of-service attacks are being launched across their wireless network."

Not everyone is pleased with the free broadband movement. NYCWireless and other communal broadband groups are being scrutinized by vendors of high-speed Internet access, like AT&T Broadband. Some liken shared residential broadband connections to cable television theft.

Hunter Middleton, a group manager for consumer product marketing at Covad Communications, says the company is able to monitor traffic patterns for abnormal usage levels and will take steps to stop what he terms "abuse" of terms-of-service contracts. He warns that Covad subscribers may be held responsible for outsiders who use shared connections to download pornography or spread viruses.

"Do you want the FBI knocking on your door because of something that another user did with your DSL line or some other broadband service?" Middleton asked. "When you don't know your neighbor, and you're giving your neighbor that access, you're opening up your home, your computers, your own reputation to what those other people do."

Verma said he shares those security concerns.

"Wireless networks have a security problem," Verma said. "Our problem is, since we are an urban campus, somebody could drive by, park, and connect to our network, which then violates our contract with our ISP because the service is supposed to be for campus."

For its part, NYCWireless recommends its members purchase wholesale broadband connections, which can usually be shared or resold without violating contractual terms of service. Meanwhile, the group is thinking big -- Townsend said they hope to bring free Internet access to everywhere from low-income New York neighborhoods to Grand Central Station.