Vulnerability Development mailing list archives

Re: Possible flaw in XFree?


From: Valdis.Kletnieks () vt edu
Date: Fri, 28 Jun 2002 12:48:21 -0400

On Thu, 27 Jun 2002 16:06:55 -0300, "William N. Zanatta" <william () veritel com br>  said:


   5. Then, 'ctrl-alt-backspace' and voila... X is down and my console 
is there, opened for me.

Working as designed.

XFree is just following the X Consortium here - X servers have used
control-alt-backspace as a "shutdown now" hotkey at least as far back
as X11.1 or maybe even X10.4, 15 years ago.

If this is a problem in your environment:

1) dont use 'startx', but use 'gdm' or something to manage logins.
This way, when the X server exits, you go back to the login screen.

2) 'man 5 XF86Config' and read this in the 'Serverflags section':

      Option "DontZap"  "boolean"
              This disallows the use  of  the  Ctrl+Alt+Backspace
              sequence.  That sequence is normally used to termi-
              nate the X server.  When this  option  is  enabled,
              that  key  sequence  has  no special meaning and is
              passed to clients.  Default: off.

Hope this helps..

-- 
                                Valdis Kletnieks
                                Computer Systems Senior Engineer
                                Virginia Tech

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