Fake login screens

Chris Cheney ccheney at ubuntu.com
Sun Feb 15 05:06:15 UTC 2009


Even if Alt+SysRq+K does work for you it will likely cause your console
(eg Alt F1-F6) to not work again until reboot, because it doesn't
cleanly shut down the xserver like C-A-B does. I used it once recently
after C-A-B was disabled by default and it worked well enough to get X
back but after that I could not go to a console again until I had
rebooted.

Chris

On Sat, 2009-02-14 at 20:31 -0500, Mike Jones wrote:
> Mackenzie,
> 
>     Please don't think I'm just trying to stir up more noise. In
> discussion with the people using this list I've seen the wisdom in
> taking a personal inconvenience for the greater good regarding the
> C-A-B issue.
> 
>     But I've tried Alt+SysRq+K on many different computer systems I
> have access to. It doesn't seem to do anything. Could you please
> explain what I'm doing wrong? Or help me find out if I should file a
> bug report?
> 
>     Thanks so much.
> 
> -Michael Jones
> 
> 
> Message: 9
> Date: Sat, 14 Feb 2009 18:12:25 -0500
> From: Mackenzie Morgan <macoafi at gmail.com>
> Subject: Re: Fake login screens
> To: ubuntu-devel-discuss at lists.ubuntu.com
> Message-ID: <200902141812.25625.macoafi at gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> On Saturday 14 February 2009 5:43:20 pm Mario Vukelic wrote:
> > On Sat, 2009-02-14 at 16:52 -0500, Mackenzie Morgan wrote:
> > >
> > > And *YOU* are missing the point that Ctrl+Alt+Delete on Ubuntu
> > > *already* does what Windows does when you hit Ctrl+Alt+Delete but
> are
> > > actually already logged in: it asks if you want to log out.
> >
> > Nope it does not. The windows *kernel* intercepts C-A-D, user
> processes
> > can't. It's specifically designed as a way to prevent fake login
> > screens: pressing C-A-D *guarantees* a kernel-approved login.
> > http://blogs.msdn.com/larryosterman/archive/2005/01/24/359850.aspx
> >
> > Guys, doing your homework before posting would make developers more
> > likely to stay subscribed.
> 
> The point was just "a way to get logged out with a keyboard shortcut"
> but if
> you would like to still have it kill session, the kernel *does*
> intercept
> Alt+SysRq+K as pointed out a billion times already.  Seriously, we
> have a
> userspace and a kernelspace way around this one.
> 
> --
> Mackenzie Morgan
> http://ubuntulinuxtipstricks.blogspot.com
> apt-get moo





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