Re:Shameless plug (Score 1)

I should put a diagram on that page. The agents and probes report BACK via https to the monitoring server which is outside of the network. So no one has access from the outside. If the Agents or probes don't responds, that triggers an alert.

So, monitor via:
- outside server - out of the network - (can ping the outside ip)
- probe - inside of the network ( can monitor any device via snmp, wmi, scripts )
- agent - inside of the network ( can monitor the device it is installed on )