A Wire-speed Packet Classification and Capture Module for NetFPGA

Hardware-based packet classification and capture can be a useful feature for a high-speed networked device, or a useful debugging aid for NetFPGA projects. This paper presents the design and implementation details of a drop-in module for the NetFPGA framework which provides a simple but nevertheless highly flexible system for matching patterns in one or more packet headers and/or payloads and diverting such packets to the host system via DMA for inspection or recording. The module is implemented in such a way as to never act as a bottleneck to the NetFPGA pipeline, and can classify packets at wire speed. We also present an extensible software framework which allows filters to be specified and implemented by the user in a simple manner according to built-in knowledge of common protocols, provides display of captured packets via the Wireshark protocol analyser and optionally further distributes captured packets to custom processes via a publish/subscribe system for analysis and/or storage. The hardware module and associated software will be available to the NetFPGA community under a free license.