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Re: Security Implications of running startx from command line - was Re: Startx: was Great Debian experience





Le 20.03.2014 02:44, Zenaan Harkness a écrit :
Yeah, when making a machine for a less technical or less command-prompt
comfortable person, I like to have it boot into GUI via the desktop
manager. But when setting it up for myself or for people technically
sharp enough to log in and then type "startx" (and people you can
trust with the command prompt), I like to boot to the command prompt.

When logging in at the Linux console (on current kernels at least),
then running startx, there is a security problem:

Anyone with physical access to your computer could:

a) logout of your gui session (if it's not screensaver locked), taking
them back to your command line, and depending on your settings of
/etc/sudoers tty_tickets or respectively !tty_tickets setting - see
man sudoers) might give them instant root access;
either way, mischief may ensure.

b) type Ctrl-Alt-F1 (for example), followed by Ctrl-C to kill your gui
session, notwithstanding if you even have it gui locked


SO: what to do?

What I did for a while was:
a) log in to Linux console
b) startx; exit

This way, when the gui (X in this case) exits for any reason, then the
console shell session logs out automatically.

That's fine, but requires more typing, and remembering to add the
extra "; exit" command.

So to optimize, simply put the sequency "startx; exit" (or similar)
into a shell function - I use the name "se" since it's less to type :)

So now I use:
a) log in to Linux console
b) se

Happy and safe sessions to all,
Zenaan

Can't ~/.xinitrc force startx to logout?
And about TTYs, I guess that, for most users, the easiest thing to do is to disable all but one for the usual runlevel. ( /etc/inittab could help )


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