How dos net send messages are monitored

I would like to know what types and names of software can be useds and how dos net send messages are monitored. Is there a lot of work that has to be done to monitor net send messages from network. What steps do I need to take. I also would like to know if the system properties are cleared are all the net send messages cleared immediatly and would someone have to access my computer via remote software to trace the net sends.