TunnelSC is designed to help you route traffic from behind a firewall. It creates a local TCP server on a port you specify (as 'local port') and serves connections. Any connection to this port is automatically 'tunneled' to a server you specify as 'remote host' and the port you specify as 'remote port' using TunnelSVR either on a direct connection or through a proxy server (now, HTTP proxy only).
Any application that connects TunnelSC will function as if it is connected directly to a remote server. TunnelSC is not protocol-dependant so may tunnel any TCP connection. TunnelSC server could be accessible either locally (not visible from LAN) or in 'connection sharing mode' (visible from LAN, you may turn it on by unchecking 'local only'). 'Shared mode' is nice way to share some resources, available from a small group of computers to an entire LAN.