You can do just about anything on the Internet these days: watch movies, order clothes, meet new friends, ogle lewd photos—anything! And so can your kids, if they have use of a computer with Internet access. Some parents feel that this freedom goes a bit too far. Just as they wouldn't let the kids wander Times Square unescorted, parents would like to control just where kids can go on the Web. What can parental-control software do to keep kids away from the seamy side?

Different Needs for Different Users

Look first for per-user configuration options, especially if you share a computer with the kids. You don't want the software to monitor or control your own computer use, and the restrictions you'd choose for a 6-year-old are naturally different from those for a 16-year-old. Some products, like Webroot Parental Controls and PC Pandora, tie their configuration settings to Windows user accounts, which is fine if you use separate accounts for each user. Others, like Safe Eyes and NoodleNet, define program-specific accounts. This is better if the whole family uses one Windows account, but it does require a separate log-on to the parental-control system. Also, it's possible that the kids may wind up using your grown-up no-restrictions account if you forget to log out. The most flexible products, like Net Nanny and Bsafe Online, define program-specific accounts that you can optionally tie to Windows user accounts.

Categorical Imperative

One common rationale for installing parental-control software is to keep preschoolers from happening upon "adult" sites and to keep teens from visiting them deliberately. Virtually every parental-control product includes some kind of category-based Web site blocking. The number of categories varies wildly—Sentry At Home has just one (adult/porn) while PC Pandora, Web Parental Controls, and KidsWatch let you allow or block 60 different categories. NoodleNet goes further and denies access to any site not on its lists of age-appropriate approved sites. Most products use an online or local database that matches Web sites they've analyzed with one or more categories, with an option to block sites that haven't yet been categorized. Some actually analyze the page content in real time.

Real-time analysis has pluses and minuses. When the parental product actually processes each page, it can catch a brand-new porn site or a normally safe site that's been hacked to display inappropriate content, but it can be fooled by sites that put all their content in the form of images. In addition, simple-minded keyword-based blocking (as opposed to full textual analysis) will often block pages inappropriately. Some will block PC Magazine reviews that call a product "sexy." Others may find "bad" words embedded in URLs, like or Net Nanny takes a very effective combined approach. For most sites, it uses an online category database. If the site hasn't been analyzed or if the database indicates that it changes often, Net Nanny resorts to full textual analysis.

To be effective, a parental-control product must filter the incoming HTTP data stream, below the level of the browser. Otherwise it has no chance of controlling what sites a smart teen or preteen can access. Some products install in specific browsers but claim to prevent the kids from using unsupported browsers; don't believe them. There's always a browser obscure enough that it's not blocked. Only protocol-level filtering like that used by Net Nanny and Safe Eyes is effective.

Unlike the rest of the field, iShield and iShield Pro offer to block pornographic images. Using a proprietary analysis algorithm, they check every image on every Web page visited and cover up those that seem to be porn. The Web-based image blocking works only for supported browsers, but the Pro edition scans every image displayed on the screen from whatever source and covers up those it thinks are porn. That's an interesting approach. —next: Time's Up! >