Tcpreplay is a suite of BSD licensed tools written by Aaron Turner for UNIX (and Win32 under Cygwin) operating systems which gives you the ability to use previously captured traffic in libpcap format to test a variety of network devices. It allows you to classify traffic as client or server, rewrite Layer 2, 3 and 4 headers and finally replay the traffic back onto the network and through other devices such as switches, routers, firewalls, NIDS and IPS’s. Tcpreplay supports both single and dual NIC modes for testing both sniffing and inline devices.
Tcpreplay is used by numerous firewall, IDS, IPS and other networking vendors, enterprises, universities, labs and open source projects. If your organization uses Tcpreplay, please let me know who you are and what you use it for so that I can continue to add features which are useful.