Friday, December 7, 2007

How to Disable Alt+Ctrl+Bksp and Ctrl+Alt+Function Keys

System administrators should be aware that now there is the ability to turn off switching to text mode virtual terminals via CTL-ALT-FunctionKey. This can come in handy when locking down a system (such when a Linux box is used as a kiosk) when used in conjunction with disabling CTL-ALT-BKSP (forceful kill of the X server). To do this, edit your /etc/X11/XF86Config or /etc/X11/xorg.conf and add the following:

Section "ServerFlags"
# prevent the use of CTL-ALT-F1, etc
Option "DontVTSwitch" "On"
# prevent the use of CTL-ALT-BKSP
Option "DontZap" "On"
EndSection


Here the Vitrual Consoles can be locked in /etc/inittab also

Open /etc/inittab and comment the following

1:2345:respawn:/sbin/mingetty tty1
2:2345:respawn:/sbin/mingetty tty2
3:2345:respawn:/sbin/mingetty tty3
4:2345:respawn:/sbin/mingetty tty4
5:2345:respawn:/sbin/mingetty tty5
6:2345:respawn:/sbin/mingetty tty6

You can shift the Virtual Consoles from Alt+Ctrl+F1 -> F6 to Alt+Ctrl+F8 -> F12
To do so edit /etc/securetty.And rename the tty entries by the number of Virtual Terminal you want to use

eg :
console
vc/1
#vc/2
#vc/3
#vc/4
#vc/5
#vc/6
#vc/7
#vc/8
#vc/9
#vc/10
#vc/11
#tty1
#tty2
#tty3
#tty4
#tty5
#tty6
#tty7
#tty8
#tty9
#tty10
#tty11
tty12

This will enable a single Console at tty12 ie, Alt+Ctrl+F12 Keystroke
Reboot the machine to get affected by the changes made.

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