console grabbing in X

freebsd-stable at auscert.org.au freebsd-stable at auscert.org.au
Mon Aug 16 20:47:58 PDT 2004


> On Tue, 17 Aug 2004 12:42:42 +1000, Joel Hatton wrote:
> >>
> > I'm not sure what this option allows:
> >
> > # Allow ordinary users to take the console - this is useful for X.
> > options         UCONSOLE
> >
> > I have this configured in my kernel config, but I still can't run xconsole
> > as a non-root user (program launches with "Couldn't open console" error).
> > Am I misunderstanding something?
> >>
> 
> Wild guess: you need to chown/reprotect /dev/console.
> 
> Do "man fbtab" for more information.
> 
> Dan Strick

Thanks,

I should have searched first, my xconsole problem is a FAQ:

	11.15. Why do I get ``Couldn't open console'' when I run xconsole?

	If you start X with startx, the permissions on /dev/console will
	not get changed, resulting in things like xterm -C and xconsole
	not working.

	This is because of the way console permissions are set by default.
	On a multi-user system, one does not necessarily want just any
	user to be able to write on the system console. For users who are
	logging directly onto a machine with a VTY, the fbtab(5) file
	exists to solve such problems.

	In a nutshell, make sure an uncommented line of the form
	
	/dev/ttyv0 0600 /dev/console

	is in /etc/fbtab (see fbtab(5)) and it will ensure that whomever
	logs in on /dev/ttyv0 will own the console.

However, there's no mention of the UCONSOLE kernel option - does this mean
that it is not needed, or does it have another function entirely? I'd like
to know if so, so I can remove it from my config.

cheers,
-- Joel Hatton --
Security Analyst                    | Hotline: +61 7 3365 4417
AusCERT - Australia's national CERT | Fax:     +61 7 3365 7031
The University of Queensland        | WWW:     www.auscert.org.au
Qld 4072 Australia                  | Email:   auscert at auscert.org.au


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