Re: Who: No users logged

From: Glynn Clements (glynn.clements@virgin.net)
Date: 08/27/02


From: Glynn Clements <glynn.clements@virgin.net>
Date: Tue, 27 Aug 2002 17:08:20 +0100
To: Jayr Al-Dyn <jayraldyn@jayraldyn.net>


Jayr Al-Dyn wrote:

> I am worried about something I noticed this week. I am using gkrellm to
> monitor the system in a Woody box (with kernel 2.4.18), and it shows
> there are no users even when I'm logged.
>
> Again, in a shell window, a "who" command returns no users, when it
> should return at least one (jayraldyn).
>
> Should I be worried? Can it be a bug or something misconfigured?

"who" basically just dumps the contents of the "utmp" file (e.g.
/var/run/utmp or /var/log/utmp). Not all programs update this file;
terminal emulators such as xterm etc may need to be setuid root (or at
least setgid "utmp") in order to write to it.

"who" and the "utmp" are more of a convenience than a security
measure. For a start, utmp is only intended to record interactive
logins, but there are plenty of ways in which a valid user can run
code without actually being "logged in" (e.g. modify ~/.forward,
~/.procmailrc etc via FTP).

-- 
Glynn Clements <glynn.clements@virgin.net>



Relevant Pages

  • Re: Who: No users logged
    ... I am using gkrellm to ... > monitor the system in a Woody box, ... utmp is only intended to record interactive ...
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