netsniff-ng
netsniff-ng is a free, performant Linux networking toolkit. The gain of performance is reached by zero-copy mechanisms, so that on packet reception and transmission the kernel does not need to copy packets from kernel space to user space and vice versa. It contains the utilities netsniff-ng, trafgen, mausezahn, bpfc, ifpps, flowtop, curvetun, astraceroute.