How to check if a user is still active?
<p>How do i keep checking if a user still is active, for like every 1 minute? I need to know which user is currently active and who is not! I'm not using ASP.NET membership provider!</p>

<p>Lets say, maximum 3 log in are allowed for one user to log in simultaneously from 3 different locations, if the same user, which is the 4th log in, try to log in from another location again, i would like to block the 4th log in.</p>

<p>I have few issues regarding this as well! If the user unplug the connection cable or close the browser, how do i figure out if the user is still active?</p>
