Sometimes, your ADSL router shows that you are downloading or uploading something by blinking the respective LED lights rapidly, while you are not even using the web browser. It makes you wonder which program is accessing the internet in the background – especially when you are on a costly mobile internet data plan (Verizon charges $45 or 250 MB for this). Fortunately, it is not very difficult to know which of the processes are accessing the internet and connecting to which websites using the free PortExpert tool.
PortExpert is a portable Windows application that show all the active connections in your Windows PC showing the processes names, their process ID number (PID), protocol used (TCP, UDP etc.), remote IP address and remote port.
At the bottom there are conveniently placed buttons to toggle displaying of the system processes (processes related to Windows OS), and local connections (connections not going to the internet). You can also freeze the time so that the current connections data is not automatically updated which allows you to look into the displayed connections without worrying about them disappearing from the list.
For each of the connections, there are some investigations tools available. You can select one of the connections from the list and click on Whois button to find information about the remote IP address. Similarly the Search Web button allows you to google about the IP address, the Open Web button allows to open those IP addresses in your default browser and the Open Folder button locates the related process in Windows File Explorer.
Conclusion: All in all, PortExpert is a nifty tool to monitor the active network connections in a Windows PC. You can use it to investigate into suspicious connections being made by strange looking programs.
You can download PortExpert from http://www.kcsoftwares.com/?portexpert.