[Buildroot] Dropbear reports errors in system log

Michael S. Zick minimod at morethan.org
Mon Sep 12 13:07:24 UTC 2011


On Mon September 12 2011, Michael S. Zick wrote:
> On Mon September 12 2011, Will Moore wrote:
> > Buildroot dropbear is configured to log ssh access to /var/log/lastlog and
> > /var/log/wtmp as well as /var/log/utmp.  It successfully logs to /var/log/utmp
> > but reports the following entries in the /var/log/messages system log:
> > 
> > Sep 12 06:42:43 buildroot authpriv.warn dropbear[1019]: lastlog_perform_login:
> > Couldn't stat /var/log/lastlog: No such file or directory
> > Sep 12 06:42:43 buildroot authpriv.warn dropbear[1019]: lastlog_openseek:
> > /var/log/lastlog is not a file or directory!
> > Sep 12 06:42:43 buildroot authpriv.warn dropbear[1019]: wtmp_write: problem
> > writing /var/log/wtmp: No such file or directory
> > 
> > I believe these errors can be stopped either by creating /var/log/lastlog and
> > /var/log/wtmp (but this would seem to just duplicate logging) or by configuring
> > dropbear --disable-lastlog and --disable-wtmp (better).  Is there something I am
> > missing?
> > 
> > I note that other login accesses are reported to /var/log/utmp too.  Is there
> > anything stopping /var/log/utmp growing over time?
> >
> 
> A diligent administrator who does not want the default *nix behavior.
> 
> Seriously -
> The utmp file was designed to be very small in *nix systems because
> it was intended to grow over the life of the software installation.
> 
> For instance, the system on which I am writing this, that gets multiple
> logins each and every day for seven years: 3,072 bytes.
> 
> So yes, it does grow over time, unless you do something about it.
> Like, maybe delete it once a decade or when it reaches 4K bytes (one memory page).
>

My bad, I just read the manual (man utmp, man wtmp) -

According to the manual entry on this system (which may not be typical of yours) -
If the wtmp does not exist, then nothing makes it and that logging is turned off.

The story is different about utmp, it is a requirement for Linux operation.
Which does not prevent you from deleting/creating it at each reboot. 

Mike
> Mike
> 
> > Regards,
> > 
> > 
> > 
> > Will
> > 
> > 
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> > 
> 
> 
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