[ale] too many logins

[Todor Fassl]

I have a problem in a lab I am responsible for. The lab has 7 debian 
stable machines. Students log in to check mail, browse the web, etc. But 
they frequently walk away without logging out. Soon enough, the screen 
saver comes on and the next person sits down and logs in as another 
user. Often, the first person comes back hours late or the next day and 
logs in a second time. Some of these machines have the same user logged 
in 5 or 6 times.

The problem is that some of these students start matlab, sage, or magma 
jobs before they walk away from the workstation. Those are legitimate 
jobs and should not be killed.  In fact, sometimes students ssh to these 
machines and run computations. It's kind of a bad idea but I'd rather 
not tell them not to do that. Otherwise, I'd just have the machines 
reboot themselves every  night.

We used to use a tool called timeoutd but it seems to have been removed 
from the debian stable and ubuntu archives.  I was never able to get it 
to work right anyway. Students would complain that their jobs had been 
killed or that they were logged out while they were typing away. At the 
same time, I could see that other users were still logged in after 
days/weeks of inactivity. I am not sure the problem really was with 
timeoutd because finger often gave me weird results.I'm not sure linux 
was giving timeoutd correct data to work with.