Use Internet filters to erase the hate from classroom computers

Shawn P. McCarthy

April's school tragedy in Littleton, Colo., has renewed pressure on schools and libraries to screen Web hate sites from their computers.

The necessary technology has been available for some time, but there are trade-offs in using filters. Some schools ignore them. Others implement them in a ham-fisted way that screens out valuable content.

If you are a government Web manager faced with requests to screen your users from sexual, violent or hate-oriented content, you need to familiarize yourself with the options.

Vice President Al Gore's push for a national filtering standard ratchets up the urgency.

No filter is perfect, but some are very good. A properly configured Internet filter combined with adult supervision can effectively keep objectionable content off library and classroom computers. There are three basic choices:

' Let students visit only specific uniform resource locators with limited or no off-site links. This works for young surfers who want to visit, say,, but not for older students who need to research multiple sites.

' Set up a group of approved URLs with trusted links. Most Net monitoring software or a proxy server can set such restrictions. But the sites might lack specialized information the users need.

' Allow surfing into unknown areas, but set special software to screen known adult or hate sites and strip out pages with so-called stop words.

This gives the most flexibility but at the risk of letting some unknown elements slip through. The best safeguard is to place all computer monitors so that a teacher or librarian can see them.

At close range

If you choose to filter, you can select filters built into search engines, client-side commercial software or proxy server plug-ins.

Search engine filters include AltaVista Family Filter from Compaq Computer Corp.'s AltaVista unit; Ask Jeeves for Kids from Ask Jeeves Inc. of Berkeley, Calif.; GoGuardian on Disney's Go Network; Lycos SearchGuard from Lycos Inc. of Waltham, Mass.; Searchopolis from N2H2 Inc. of Seattle; and Yahooligans on Yahoo. All keep out sex, violence and hate content based on banned URLs and stop words.

Client-side software interacts with a server that maintains URL lists. It includes such products as NetNanny from Net Nanny Software International Inc. of Bellevue, Wash.; CyberPatrol from Learning Co. of Cambridge, Mass.; [email protected] from SurfWatch Software Inc. of Los Altos, Calif.; and CyberSitter from Solid Oak Software Inc. of Santa Barbara, Calif. Most such applications have preapproved or disapproved URL lists.

Packaged filtering solutions for proxy servers include WebSense for Microsoft Proxy Server from NetPartners Internet Solutions Inc. of San Diego, and [email protected] and Little Brother Pro from Kansmen Corp. of Milpitas, Calif.

Little Brother is a standalone filtering server. Most proxy solutions have large databases of blocked URLs; managers can add sites to the list or override the list as needed.

How accurate are such lists? It depends on the filtering method.

What's the word?

Hand categorization is the most accurate and most difficult. Workers attempting to identify sex, violence and hate URLs cannot hope to keep up with all the new pages and sites.

Heuristics, or rules-based algorithms, cannot anticipate every circumstance, misspelling or new phrase.

But their rules can weed out obvious problem sites and make hand-categorization less daunting.

Stop word lists involve tough choices. For example, screening out the word breast would eliminate breast cancer information. The best approach is filtering by URL along with carefully chosen stop words.

I believe a proxy server is the most reliable filter, if properly implemented.

Shawn P. McCarthy designs products for a Web search engine provider. E-mail him at [email protected].


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