Webscreen Technology is relaunching its denial-of-service mitigation appliances in the United States after 18 months of concentrating its efforts abroad.                                                 
The company was founded in the United States in 2001 and was bought by a group of U.K. investors in 2005. With its return to the United States it is announcing Webscreen 3.0, an upgrade to its flagship product that adds bandwidth optimization tools.

Webscreen appliances sit outside corporate firewalls and protect Web sites from distributed DoS attacks by evaluating what traffic can be trusted and what traffic can’t. It constantly ranks traffic from trusted to untrusted so the most suspect traffic is dropped first during attacks.

The devices are typically installed in learning mode for a week to determine normal traffic patterns before they are switched on in defense mode. Inspection is performed based on an algorithm, and the device uses no pattern matching to determine suspicious traffic.

The device begins to block traffic only when attacks are severe enough to degrade performance of a Web server, the company says.

Version 3.0 enables reserving bandwidth for key applications and users even in the midst of an attack. This can reserve capacity for essential business tasks and reduce the need for adding bandwidth to Internet links to overcome the volume of unnecessary traffic.

The software maps where attacks are coming from and distributes this data among all the Webscreen devices protecting the various Internet access points in a network. This helps ward off attacks if they shift from one site to another.