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.
TcpView For Linux - TcpView For Linux. Touch screen friendly design graphical network connections viewer for Linux.
Angry IP Scanner - Open-source and cross-platform network scanner designed to be fast and simple to use
PortsMonitor - PortsMonitor is a system utility for monitoring system TCP/IP network connections by application...
TCP Optimizer - SpeedGuide.net - The Broadband Guide. Cable modems, DSL, Wireless, Network security. Free speed tweaks and TCP/IP tools for optimizing system performance.