Packet Sender - Packet Sender can send and receive UDP, TCP, and SSL on the ports of your choosing.
iperf - A TCP, UDP, and SCTP network bandwidth measurement tool
Portfwd - Portfwd, Port Forwarding Daemon, stands for port forwarding daemon.
TamoSoft Throughput Test - TamoSoft Throughput Test is a utility for testing the performance of a wireless or wired network.
PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
netperf - Netperf is a benchmark that can be used to measure the performance of many different types of networking. It provides tests for both unidirectional throughput, and end-to-end latency. - HewlettPack...