PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
Komodia Relay - Free open source tool to perform TCP based session relay
socat - socat is a relay for bidirectional data transfer between two independent data channels.
Portfwd - Portfwd, Port Forwarding Daemon, stands for port forwarding daemon.
netcat - Netcat is a featured networking utility which reads and writes data across network connections...
Packet Sender - Packet Sender can send and receive UDP, TCP, and SSL on the ports of your choosing.