Re: Linux login security approaches

Zow (zow@torii.bruggerink.com)
Mon, 07 Dec 1998 21:35:54 -0800


> I mentioned that Linux has got a weak point : every user can write a fake
> login program and even the system administrator can think that it's mgetty
> and type the root password :( This kind of Trojan programs can be preceded.
> We should define a key combination which is unmaskable by ANY process, and
> login procedures should begin by pressing this combo. However I was told that
> this is "an NT way" solution, but I disagree. (I don't know anything on

That is what NT does, but I remind everyone that just because NT does
something doesn't make it inherently bad. I actually think many of the ideas
in NT are great, but the implimentation, support, marketing, etc leave too
much to be desired.

On x86 NT machines (anyone know about Alpha?) one must press Ctrl-Alt-Del in
order to pull up a login screen. Ctrl-Alt-Del can't be caught by user progs,
only by the system and it works exactly as you specify. In the case of xdm,
you would have to hit that key combo before the chooser came up. I know that
Linux runs a program when it catches Ctrl-Alt-Del . This program is specified
in inittab: it is usually "/sbin/shutdown -r". You could create a modified xdm
that is run from inittab on Ctrl-Alt-Del. It could act differently based on if
a user is logged in or not. I could go on, but I would basically just describe
what NT does. I suggest that anyone who's interested in this go play with an
NT box. You'll learn about this as well as appreciate Linux more when you're
done.

<snip>
> bye : Gábor Lénárt,
>
-"Zow"

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