The Brooks administration wants the internet filtered at all times on library computers, but things seem a little less certain with Brooks' proposal to create free wi-fi zones in parts of Rochester, Greece, and Pittsford.

The county plans to let Frontier Communications develop a subscriber-based wireless network by attaching equipment to county-owned traffic signals, light poles, and buildings. In lieu of payment, the company will provide free and reduced-fee user accounts to the county. It will also establish free zones for public use. (The exact locations have yet to be determined). The proposal, which has been approved by the County Legislature's Ways and Means Committee, will be up for a vote at the legislature's May 8 meeting.

Will those free public hot spots be filtered? County officials haven't said no, but they haven't said yes, either.

"All other details on the network will be unveiled in the future," county spokesperson John Durso said in an e-mail last week.

Wi-fi filtering is possible, and several cities have it in place on their public networks. Culver City, California, uses technology to block access to pornography as well as to protect copyrighted material. Boston selectively blocks specific sites deemed offensive for some reason.

Public wi-fi network filtering is more complicated than it would be for wired networks in places like schools and libraries, according to Sid Pendelberry, senior systems administrator and engineer at Rochester Institute of Technology. That's especially true, he says, when it comes to blocking a category of sites, as opposed to targeting a specific site.

To block pornography, for example, a device would have to inspect the content of "conversations" between a private computer and the website distributing the material. In techie terms, the process is called packet inspection. And the process has limits. It has to be based on words and processes.

But Pendelberry believes the county may be better served by focusing on filtering out viruses and malware (a technical term for malicious programs like spyware) and blocking known bad sites.