TCPView - TCPView is a Windows program that will show you detailed listings of all TCP and UDP endpoints on...
CurrPorts - CurrPorts displays the list of all currently opened TCP/IP and UDP ports on your local computer.
Proc Net Monitor - SecurityXploded is an Infosec Research Organization offering 200+ FREE Security/Password Recovery Tools, latest Research Articles and FREE Training on Reversing/Malware Analysis
Advanced Port Scanner - Advanced Port Scanner is a fast and free software for port scanning.
Total Network Monitor - Total Network Monitor is a network monitoring software that is designed to continuously monitor your local network, individual computers, and services. Free for 60 days.
Advanced IP Scanner - Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off. Download it Free.