Hi Tiong,
Diu King,Tiong (12/13/2011)
can i detect all who are the users access to the system within same network?
There is nothing in SF that will do that. What I do is I have my own LoggedUsers table which I update when user log in/out and then I can know which one are logged. I know it is not perfect in case the application crash, but so far SF framework is so stable that I have not had any crash notification by my users.