Sessions/security

Hi all, I have the following questions concerning sessions/security/...: -A- Is there any way, how to handle, whether the user leaves my site? I know, how to deny access, when user comes to my site from another for the first time (after browser launch), or from another page of my site. What I want is, to deny the access, when user logs into my system, then leaves it without logging out and then goes back (via history, or manually). I know, I can erase history but it means, the user would not be able to go back inside the system and it also does not solve the problem with manual URL input. -B- How can I differenciate, which browser window on one computer is being used. I'd like, for instance, enable the users to log in twice as different users from 1 computer at simultaneously. Thanx for any both hint and smile at my humble questions. -- __________________________________________________________________________________________ ========================================================================================== Jan Walter, called John LERACH, s.r.o. phone nr. work: +420-2-78 22 619, home: +420-2-35 35 27 61 on emergency call cell phone: +420-602-385 760 work e-mail mailto:Jan.Walter@lerach.cz private e-mail mailto:john@lerach.cz ICQ#: 28353428 __________________________________________________________________________________________ ==========================================================================================