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Businesses that want to limit employee Internet access to only business-related content and services have the luxury of choosing from a variety of Web content-filtering solutions. The techniques these products employ range from simple blocked-URL lists to network appliances that "learn" and can make dynamic policy changes. The appropriate Web content-filtering solution for your business depends on factors such as your company's size, type of business, resources, network infrastructure, and corporate culture. For example, in one company, downloading music files during business hours might be a necessary business-related activity, whereas in another company, the same action might result in an employee being asked to clean out his or her desk.

In many ways, the term Web content-filtering solutions is too narrow to describe this group of products. The solutions in this Buyer's Guide offer wide-ranging capabilities that you might or might not need. Compare your requirements with the product descriptions in the accompanying table and do the necessary research before you buy.

Some products, such as Deerfield.com's Cobian Orange Filter and LogiSense's EngageIP Content Filter, concentrate exclusively on HTTP-delivered content; other products can also filter and control content delivered by additional protocols. If you want to block access to services such as FTP, Instant Messaging (IM), Internet Relay Chat (IRC), and music downloading (e.g., Kazaa) or to protocols such as Network News Transfer Protocol (NNTP), make sure that the product you choose has this capability.

Rather than being standalone systems, some products, such as Secure Computing's SmartFilter and FilterLogix's Intelligent Content Manager, are add-ons to existing firewalls, proxy servers, or gateways. If you consider such products, make sure that they'll integrate with your existing infrastructure. Browse the company's technical support knowledge base for information about any compatibility problems with your specific hardware.

Pricing is also an important consideration, and the pricing models of Web content-filtering products vary widely. In general, you can expect to pay either a per-user fee or a flat fee for multiple users. In addition, some companies charge annual fees for licensing, support, and updates. For example, a four-server license for NetIQ's Web Marshall Enterprise Edition costs $2000 plus $750 for 100 users. St. Bernard Software's iPrism network appliance includes a 250-workstation license and 1-year subscription for $5490. You can install Secure Computing's SmartFilter on an existing appliance, firewall, or proxy server for $25 or less per user.

Before you purchase a product, evaluate its reporting capabilities, which can be an important feature if you become embroiled in a legal dispute with an employee. Also, consider the ease with which a product's configuration tools let you restrict content or make it accessible. Many products have Web interfaces that let you remotely manage content filtering. Evaluate the administration system's built-in security—does the product securely store passwords, support encryption, and maintain logs of policy changes?

The most effective systems know which Web sites are objectionable or block restricted sites according to company-specified policies. Web content-filtering vendors often use marketing terms such as artificial content recognition, artificial intelligence (AI), and coaching to describe how their content-blocking engines work. Cut through the marketing buzz by comparing the methods products use to make requests with continuously updated blocked-URL lists—databases that you don't have to manually maintain. Accurate lists and the ability to correctly classify URLs are paramount for an effective Web content-filtering system. Look at factors such as the frequency of updates, the database size, and the intelligence of the blocking engine. To facilitate these important tasks, some vendors maintain a support staff that categorizes and ranks database entries.