Connection Monitor is a Free Stand Alone Portable utility that can be used to monitor inbound and outbound socket connections. knowing which network and internet connections are taking place can help you keep your network secure. Connection Monitor scans existing connections and displays the local address and port, remote address and port, TCP UDP protocol and status of those connections.

Connection Monitor

Authors Website: Connection Monitor appears to have been abandoned by it's author.
You might find CurrPorts Port monitoring software or the Networx network monitor to be good replacements.
License: Freeware
Supported OS: Windows