Comparing and improving current packet capturing solutions based on commodity hardware

Capturing network traffic with commodity hardware has become a feasible task: Advances in hardware as well as software have boosted off-the-shelf hardware to performance levels that some years ago were the domain of expensive specialpurpose hardware. However, the capturing hardware still needs to be driven by a well-performing software stack in order to minimise or avoid packet loss. Improving the capturing stack of Linux and FreeBSD has been an extensively covered research topic in the past years. Although the majority of the proposed enhancements have been backed by evaluations, these have mostly been conducted on different hardware platforms and software versions, which renders a comparative assessment of the various approaches difficult, if not impossible. This paper summarises and evaluates the performance of current packet capturing solutions based on commodity hardware. We identify bottlenecks and pitfalls within the capturing stack of FreeBSD and Linux, and give explanations for the observed effects. Based on our experiments, we provide guidelines for users on how to configure their capturing systems for optimal performance and we also give hints on debugging bad performance. Furthermore, we propose improvements to the operating system's capturing processes that reduce packet loss, and evaluate their impact on capturing performance.