Remotely check login status

[Christian Eibl <chreibl () gmx de>]

Hi all,

I was wondering, if there exist means of checking remotely whether someone 
is already logged onto the system. Since most modern systems today need 
users to input their authentication data instead of automatically provide 
full access, there obviously are different states in the operating systems, 
i.e., just completely started up or even with users active in the system.

This question does not aim at a specific OS but is meant for all systems. 
The most obvious way of such checks would consist of specific network 
services only started by certain users on the systems. Well, I am no 
Windows geek, but I could also imagine that file or printer sharing 
together with this port 139 / 445 stuff could provide information about 
this, but I am not sure...

Anyone an idea how or whether this is possible? It is especially interesting 
concerning privacy within networks.

Regards,
Christian

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