tcpreplay v4.4.4 releases: Pcap editing and replay tools for *NIX and Windows

Tcpreplay is a suite of GPLv3 licensed utilities for UNIX (and Win32 under Cygwin) operating systems for editing and replaying network traffic which was previously captured by tools like tcpdump and Ethereal/Wireshark. It allows you to classify traffic as client or server, rewrite Layer 2, 3 and 4 packets 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 in-line devices.

Tcpreplay is used by numerous firewalls, IDS, IPS, NetFlow, and other networking vendors, enterprises, universities, labs, and open source projects. If your organization uses Tcpreplay, please let us know who you are and what you use it for so that I can continue to add features which are useful.

Tcpreplay is designed to work with network hardware and normally does not penetrate deeper than Layer 2. Yazan Siam with sponsorship from Cisco developed tcpliveplay to replay TCP pcap files directly to servers. Use this utility if you want to test the entire network stack and into the application.


  • Edit PCAP files
  • Replays PCAP files to devices under test (DUT)
  • Designed for IDS/IPS
  • NetFlow testing
  • Up to 10GigE wire rate playback
  • Flow performance testing

The Tcpreplay suite includes the following tools:

Network playback products:

  • tcpreplay – replays pcap files at arbitrary speeds onto the network with an option to replay with random IP addresses
  • tcpreplay-edit – replays pcap files at arbitrary speeds onto the network with numerous options to modify packets on the fly
  • tcpliveplay – replays TCP network traffic stored in a pcap file on live networks in a manner that a remote server will respond to

Pcap file editors and utilities:

  • tcpprep – multi-pass pcap file pre-processor which determines packets as client or server and splits them into creates output files for use by tcpreplay and tcprewrite
  • tcprewrite – pcap file editor which rewrites TCP/IP and Layer 2 packet headers
  • tcpbridge – bridge two network segments with the power of tcprewrite
  • tcpcapinfo – raw pcap file decoder and debugger

Changelog v4.4.4