netcat - Netcat is a featured networking utility which reads and writes data across network connections...
socat - socat is a relay for bidirectional data transfer between two independent data channels.
Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
Komodia Relay - Free open source tool to perform TCP based session relay
SmartSniff - SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers.
Simple Port Forwarding - Simple Port Forwarding works with WebPages and not directly with your router.