TCPView is a program which shows detailed information bout the TCP and UDP protocols of the system, including local and remote address and the state of the TCP connections.
For Windows NT, 2000 and XP TCPView also shows the name of the process which is making the connection.
TCPView shows more information than Netstat, which is included in Windows. When you download TCPView you may also use Tcpvcon, which is a utility with the same functions, but that is used in the command console.
When you execute TCPView, you’ll see a list with all the active TCP and UDP connections, resolving all IP addresses and showing the domain name. TCPView updates itself by default every second but you may change the updating frequency. You may also close established TCP/IP connections (the ones labeled ESTABLISHED). Besides you may also save outgoing information in a text file.
It is a good tool to monitor your net connection.