Hopefully by this point, you’ve put the cybersafety issue into perspective, implemented some basic measures to protect your kids online, and used resources to help teach kids how to protect themselves. Now it’s time to talk about filtering Internet access.

Conceptually, web filters are very simple. When using a filtered computer, requests for web pages, pictures, and other resources are first sent to the filter. Based on keywords, databases of allowed or blocked sites, and other factors, the filter determines if access to the resource should be allowed. If it is, the filter allows the computer to access it. If it isn’t, the filter blocks access to it.

It’s important to know that all filters have limitations, and some of them are pretty significant. With thousands of web pages being added, removed, and modified on a daily basis, it is impossible for any database to keep up with the ever-changing list of sites that should be blocked based on a certain set of criteria. It is also much more difficult to filter multimedia (pictures, audio, video) than it is to filter text. Text can easily be compared with certain blocked words to determine the nature of the content. It’s a lot more difficult for a computer to tell if the people in that picture have clothes on.

This problem is complicated by the increasing interactivity of the web. As more and more sites allow viewers to contribute their own content, they lose some of the control of those sites. It’s possible, for example, for someone to post inappropriate content in a comment on a CNN.com news story. That doesn’t necessarily mean Internet filters should block CNN.

It is also worth noting that a determined person can nearly always circumvent the filter entirely. Because students read this blog, I’m not going to go into too much detail here, but if you can get a web request to go directly to the Internet, rather than through the filter, you can access anything you want.

The final caveat, before we start talking about filtering solutions, is to note that many web filters are just that — WEB filters. They may not filter content in email, instant messages, or other types of Internet activity.

With all of that said, there are two basic types of filters available. The more complex of these is installed on a server. Computers on the network are configured (or forced) to access the web through this server. This has the major advantage that the computers being filtered are not running the filtering software. This makes it much more difficult (though not impossible) to disable or circumnavigate the filter. Because this requires a local network, server, and (maybe) packet routing and filtering, we’re going to assume that this is beyond the scope of most home users.

The other type of web filter uses software or a software configuration on the computer itself. While this has the disadvantage of being defeated by those being filtered if they can change the settings or uninstall the software, it is a much more manageable solution for most parents.

Filters
All right. Enough with the caveats and provisos. Where are the filters, already? Here are some free ones that come pretty highly recommended. The descriptions are paraphrased from the web sites for the software:

K-9 Web Protection: This software prevents the computer user from viewing Web sites that contain unwanted content. It can block more than 55 different categories of content, including pornography, hate speech and sites that promote violence or permit gambling. It’s free for home use.

Naomi: Naomi is a free internet filtering program intended for families. It is able to constantly monitor all internet connections, protecting children from inappropriate online material. Naomi examines in real-time all the data being transmitted and received through any internet application – such as web browers, chat programs, and news readers.

OpenDNS Adult Site Blocking: Adult site blocking is a free service that lets you block adult websites on your network. The software uses site categories compiled by St. Bernard Software, who have human-reviewed tens of millions of domains, to make sure you get the most comprehensive, easy-to-use adult site blocking service ever.

X3Watch: Rather than blocking access to inappropriate sites, this software simply logs the access, and emails those logs to a person you specify. It’s used more to monitor access than control it. The free version contains the basic features, and there’s also an advanced version available for a fee.

I haven’t actually used any of these products, but from what I’ve read, they seem to be the best of the free products. If I were setting up filtering in my home, I would start with one of these.