tcpreplay

tcpreplay [-i interface] [-M mbps] [--loop n] [options] pcap

tcpreplay replays previously captured network traffic from pcap files back onto the network. It reads packet captures produced by tools like tcpdump or Wireshark and transmits them through a specified network interface at controlled rates.The tool provides flexible speed control: traffic can be replayed at the original recorded speed, at a fixed rate in Mbps, at a speed multiplier, or at maximum wire speed with --topspeed. The --loop option repeats the capture file multiple times, and -K preloads the entire file into memory for consistent high-speed replay.Common use cases include testing network devices like firewalls and IDS/IPS systems, stress-testing network infrastructure, reproducing network issues for debugging, and benchmarking network applications under realistic traffic conditions.

-i IFACE

Output interface.

Rate in Mbps.

Speed multiplier.

Loop count.

Maximum speed.

Preload into memory.

Requires root for raw socket access. Replaying traffic on a production network can cause disruption. The interface specified with -i must be up. For editing packets before replay, use tcprewrite.

tcpreplay was created for replaying captured network traffic for testing network devices and applications.

tcpdump(1), wireshark(1), tcprewrite(1)