Sophos has released a Web filtering appliance for business users, one of several vendors adding the technology to their security product line-up.

The WS1000 appliance, which sits at the gateway, is designed to stop users from infecting their computers with harmful programs as a result of Web surfing, said Graham Cluley, senior technology consultant for Sophos, on Tuesday.

Web filtering software and appliances are a growing area for security vendors, as they offer the advantage of stopping malicious code and executables before they reach the desktop. They aren't a replacement for desktop antivirus software, however, as users can still infect their machines by clicking on, for example, a link in an instant message or an e-mail.

The WS1000 has several features to control Web traffic. It can block Web sites that administrators don't want users to view, and it also scans Web sites for malicious code as users visit Web pages.

The appliance checks against a database of Web sites to see if a site has been flagged for malicious activity. The company scans the Web for sites that look suspicious and they are added to the database every five minutes, Cluley said.

Sophos has also struck a partnership with SurfControl, a security vendor that produces a database of bad Web sites. SurfControl's database will soon be integrated into the WS1000, Cluley said.

The appliance also includes Sophos' behavioral genotype technology, which can block a file if it shares characteristics with similar malware even if a sample of the malware has not been seen before.

Sophos hopes the appliance will push its other products into companies that aren't using its antivirus software, Cluley said. The WS1000 can alert an administrator if a desktop tries to access a banned URL (uniform resource locator), highlighting the failure of the desktop antivirus software.

The WS1000 is aimed at organizations with 100 to 1,000 users, although more appliances can be used for bigger companies.

The appliance is available now, priced in the U.K. at £2,750 ($5,314) for the hardware, plus £3,540 per year for 500 users.