socat - socat is a relay for bidirectional data transfer between two independent data channels.
Scapy - Scapy is a powerful interactive packet manipulation program.
PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
Nipper - Nipper - Neat Internet Protocol Packet EditoR - is a graphical packet generation tool.
Simple Port Forwarding - Simple Port Forwarding works with WebPages and not directly with your router.
packeth - packeth is GUI and CLI packet generator tool for ethernet.