Virtualization and cloud computing have required another evolution in the firewall. In this new virtualized environment, virtual firewalls can protect resources from the Internet (in this case, virtual machines hosting Internet-facing services such as HTTP). This new technology is based on traditional firewall technology and is an implementation of policy between multiple networks. The principal difference between this new implementation of the firewall and other implementations of this technology is that it may reside as a virtual appliance on the hypervisor or as an integral part of the hypervisor.

This methodology describes how NSS will evaluate virtual firewall products to provide an objective and fair assessment of the technology.