SmartSniff - SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers.
OctoPerf - OctoPerf is a SaaS load testing solution, based on JMeter.
tcpdump - tcpdump is a common packet analyzer that runs under the command line.
WebLOAD - WebLOAD - The most flexible and cost effective software for enterprise load, stress and performance testing, integrated with DevOps processes. Click for details
Packet Sender - Packet Sender can send and receive UDP, TCP, and SSL on the ports of your choosing.
StresStimulus - Load testing tool for websites and mobile that works with hard-to-test applications.