How to measure packets per second or throughput on high speed network interface

Most traffic monitoring tools are powered by libpcap, which is a packet capture library used to monitor network traffic in user space. Despite their versatility, however, libpcap-based network monitoring tools cannot scale to handle traffic on multi Gigabit rate network interfaces, due to the overhead associated with user-space packet capture. This tutorial presents simple shell scripts that can monitor network traffic on per-interface basis, without relying on slow libpcap library.