Re: [gentoo-user] Re: How to poweroff the system from user?

[Peter Humphrey]

On Sunday 22 March 2015 13:04:44 Nikos Chantziaras wrote:
> On 22/03/15 12:30, Peter Humphrey wrote:
> > On Saturday 21 March 2015 16:20:17 Jc García wrote:
> >>> Interesting. But as I said ealier, I can reboot the system when I am a
> >>> user by Ctrl+Alt+Delete. The user can reboot the system, but can't
> >>> shut
> >>> down? Strange
> >>
> >> It's not strange,  `man 2 reboot`. It's a defined behavior.
> >
> > I'm with German here. Being designed that way doesn't stop it being
> > strange.
> >
> > Consider: I'm an ordinary user sitting at a terminal. I'm not allowed to
> > halt the machine, but I am allowed to reboot it into perhaps some quite
> > other configuration. Or I can keep rebooting it over and again,
> > effectively preventing the machine from doing its job. How does that
> > make sense?
> The thinking is that you can unplug the machine, or press the hardware
> reset or power button, or flip the PSU switch...
>
> Preventing a ctrl+alt+del reboot does not add anything to security.
> Security doesn't really apply to users with physical access to the
> machine.

Indeed, as witness many successful hijacks of supposedly secure systems.

> However, this is just a default. You can easily disable reboot on
> ctrl+alt+del by editing /etc/inittab and commenting-out this line:
>
>    ca:12345:ctrlaltdel:/sbin/shutdown -r now

All good sense.

> Note though, that is someone wants to reboot, and ctrl+alt+del doesn't
> work, pressing the reset button is far worse, since there's no clean
> shutdown performed (unmounting filesystems after flushing caches, etc.)
> Because of that, the default of allowing ctrl+alt+del for local users
> makes more sense than disabling it.

And there's no arguing with that!  :_)

-- 
Rgds
Peter.