There is no way to directly monitor ports. At least not that I know of.
I use the External Process monitor along with an application which is freely available for download from Microsoft called Portqry:
I schedule a task to run Portqry every so often. Ths app checks that a specified port(s) is/are open and write the result to a log file.
I've then created an external process monitor which reads the log file and looks for strings 'listening' and 'filtered', etc and alerts me accordingly.
I've used this method to monitor many connections and so far it has been very effective. give it a go...