[App_rpt-users] Monitoring an allstar node?

I have a working hub-type configuration, which will work well enough until I get the radio hardware hooked up. :) I have noticed some people are able to find out what node is transmitting by, I assume, monitoring something on their local system. Can anyone give me a hint about how this might work? I would love to have a GUI client that showed graphically the node interconnections, which node is keying up, etc. If there is a lower level protocol I could use (through IAX2, or some call-out from app_rpt) could I be given a hint on where to start looking? --Michael