1. Tool to replay saved tcpdump files at arbitrary speeds Tcpreplay is aimed at testing the performance of a NIDS by replaying real background network traffic in which to hide attacks. Tcpreplay allows you to control the speed at which the traffic is replayed, and can replay arbitrary tcpdump traces. Unlike programmatically-generated artificial traffic which doesn't exercise the application/protocol inspection that a NIDS performs, and doesn't reproduce the real-world anomalies that appear on production networks (asymmetric routes, traffic bursts/lulls, fragmentation, retransmissions, etc.), tcpreplay allows for exact replication of real traffic seen on real networks. From Debian 3.0r0 APT