The packetdrill scripting tool enables quick, precise tests for entire
TCP/UDP/IPv4/IPv6 network stacks, from the system call layer down to
the NIC hardware. packetdrill currently works on Linux, FreeBSD,
OpenBSD, and NetBSD. It can test network stack behavior over physical
NICs on a LAN, or on a single machine using a tun virtual network
device.

WWW: https://code.google.com/p/packetdrill/