Portmon

Portmon is yet another one of Sysinternals’ powerful utilities that monitors and logs the activity of all serial ports, allowing you to observe the behavior of several applications reported to certain ports.
It can also play a major role in identifying problems related to serial and parallel ports by inspecting the log files generated by its inner engine.
Portmon doesn’t rely on appearance to make an impression, but rather on its functionality and sophisticated monitoring technology that makes its core.
Although lacking eye candying elements, the program’s GUI is intuitive enough and comfortable to work with. All of the port activity, including the time of the connection, as well as the process involved in its exploitation, the request type and the result are displayed neatly inside the main window.
Portmon is capable of performing remote monitoring, allowing you to request logs on multiple remote computers at the same time. What’s more, the client software will automatically install itself if the capturing is being done from a computer in the same neighborhood (for Windows NT/2K systems).
The built-in filtering engine allows you to include or exclude strings from the logs and it also remembers the most recent filter scenario. You can also set it to highlight entries that match user-defined strings.
The reports issued by the application can easily be saved locally, although it is also possible to send content to the clipboard in a selective manner (select multiple lines and paste them to the clipboard).
Overall, Portmon makes a good impression especially that it can monitor the port activity of remote computers, which turns it into the perfect asset for network admins.