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.
Simple Port Forwarding - Simple Port Forwarding works with WebPages and not directly with your router.
tcpdump - tcpdump is a common packet analyzer that runs under the command line.
PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
pwncat - pwncat - netcat on steroids with Firewall, IDS/IPS evasion, bind and reverse shell, self-injecting shell and port forwarding magic - and its fully scriptable with Python (PSE)