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Grex Info Item 149: Inactive connections -- a problem?
Entered by roz on Thu May 19 10:51:58 UTC 1994:

I am online at 6:45 a.m. and notice that of 14 people logged in,
seven connections have been inactive for between 2 and 8 hours.
Is this a problem for grex, in terms of making things run slower,
or otherwise gobbling up resources?  If so, is it possible to put
something in place that knocks people off the system after, say, 
an hour or two of inactivity?

6 responses total.

#1 of 6 by mju on Thu May 19 16:10:13 1994:

If the person is connected on a network port (ttyp, ttyq, or ttyr)
then they're using only negligable resources if they're idle.
It would not be worthwhile to bother kicking off idle network users
(especially since gregc and I are the two people you'll most often
see idle for long periods of time on a network port... :-) ).

On the other hand, people idle for long periods (or even logged on for
long periods) on the dialin ports (ttyh) are a large drain on a
resource, since no one else can use that modem while they're logged
on.  However, the number of people who stay logged on for a long
period of time on a dialin port is fairly small, and so far staff has
been okay dealing with them manually.  In addition, the task of
writing an idle-killer that properly deals with "idle-but-not-idle"
connections such as file transfers is fairly large, and probably not
worth spending a lot of time on.

#2 of 6 by kentn on Thu May 19 16:50:27 1994:

Do you consider the possible security problems of someone leaving an
idle terminal to be of significance?

#3 of 6 by bubbles on Thu May 19 17:19:59 1994:

And do idle users use up swap space?

#4 of 6 by scg on Thu May 19 17:50:37 1994:

Whether an idle terminal would be a security problem would probably depend
on where that person was.  If they're in a computing center or some other
public place, it would be a problem.  But if it's in a private office, or
in somebody's house, it's probably not a problem.  But the thing to keep
in mind there is that all anybody could get into was the person's account
who left it idle, and couldn't do anything to anybody else that they
couldn't do simply by running newuser.  So if somebody loses their mail
files or their privacy by leaving their computer idle and logged in in a
public place, I'd say that's their problem.

#5 of 6 by srw on Sun May 22 04:14:57 1994:

Idle users *do* use up swap space. The amount is dependent on what processes
are left idling. This can only be determined by examinging output
from the ps command. typically, though, I'd guess that these folks
aren't leaving more than a csh or sh shell around. I'd expect minimal
impact on our total swap space from this.

#6 of 6 by dam on Mon Jun 27 01:56:18 1994:

since we also have a 24 ptty limit right now, each idle user is taking
up about 4% of that resource.

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