show logged in users

[Fretz Marco]

hello

anohter question: whats the best way to see which users are logged in?
- reading out the pppoe router with snmp for active sessions
- search for session ids with start but no stop event

i want do the first one. becuase our routers are in isolated management 
network and i want access the router from our webinterface or some admin 
hosts....

can i be 100% sure that a user is logged in if there is no stop event?

thanks and kind regards
 marco fretz