Smoothwall has added malware detection and blocking to its Corporate Guardian web filter, and said it will also sell the product as a complete appliance, based on IBM server hardware.

The software now includes anti-virus scanning and improved spyware detection, as well as controlling web usage via dynamic analysis of a page's contents, said Smoothwall managing director George Lungley.

"Most people have fairly good email protection now, so the focus has shifted to web threats," he added. "When new vulnerabilities come out, hackers will place exploits on well known and trusted sites - not the big commercial ones, but blogs and the like."

Now at version 5, Corporate Guardian runs on Linux and can also run as a module alongside the Smoothwall firewall. It is based on a freeware web filter called DansGuardian which was written by Smoothwall's technical director Daniel Barron.

"It's a commercial extension of open source, like our firewall," Lungley said. "We round the products out, add more management controls and reporting, make them work with Active Directory and offer commercial support - not the part-time voluntary support you get with open source."

He claimed that Corporate Guardian undercuts rival web filter software on price by as much as 50 percent. It starts at £400 for a ten-user system but additional user licences are far cheaper, falling to just a few pounds a seat for 1000 or more. He was unable to quote prices for the appliance version, however.

However, Nigel Hawthorn - a VP at rival security developer Blue Coat - questioned the wisdom of introducing a standalone appliance at a time when companies are adding features like web filtering to their existing UTM (universal threat management) devices.

"A lot of standalone products are now just features," he said. "And the street prices of content filters are falling. Web filtering is only 20 percent of our revenue so a 50 percent drop in prices doesn't worry me, but for someone like Websense it's a big problem."

It's performance that's the issue, responded Lungley, hence the option to run Corporate Guardian on the firewall if desired.

"You could do it on one box for a few hundred users," he said. "Web security is much more processor-intensive than firewalling though.

"A UTM-type device is good for small to mid-sized organisations, but for larger numbers of users it's asking too much of a single piece of hardware to do all those different functions."