TCPView - TCPView is a Windows program that will show you detailed listings of all TCP and UDP endpoints on...
socat - socat is a relay for bidirectional data transfer between two independent data channels.
Connections Viewer - Connections Viewer is a useful network software utility with the primary focus of listing (and managing) both UDP and TCP connections inside the host system.
PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
CurrPorts - CurrPorts displays the list of all currently opened TCP/IP and UDP ports on your local computer.
Portfwd - Portfwd, Port Forwarding Daemon, stands for port forwarding daemon.