Network processor acceleration for a Linux* netfilter firewall

Network firewalls occupy a central role in computer security, protecting data, compute, and networking resources while still allowing useful packets to flow. Increases in both the work per network packet and packet rate make it increasingly difficult for general-purpose processor based firewalls to maintain line rate. In a bid to address these evolving requirements we have prototyped a hybrid firewall, using a simple firewall running on a network processor to accelerate a Linux* Netfilter Firewall executing on a general purpose processor. The simple firewall on the network processor provides high rate packet processing for all the packets while the general-purpose processor delivers high rate, full featured firewall processing for those packets that need it. This paper describes the hybrid firewall prototype with a focus on the software created to accelerate Netfilter with a network processor resident firewall. Measurements show our hybrid firewall able to maintain close to 2 Gb/sec line rate for all packet sizes, a significant improvement over the original firewall. We also include the hard won lessons learned while implementing the hybrid firewall.