shutdown supports the use of a file /etc/shutdown.allow to list users who are allowed to perform a soft Control-Alt-Delete shutdown. To take advantage of this a flag must be added in /etc/inittab. This flag has no adverse effects even if /etc/shutdown.allow is non-existant. In /etc/inittab simply add -a to the shutdown command to enable this feature. ca::ctrlaltdel:/sbin/shutdown -t3 -r now becomes ca::ctrlaltdel:/sbin/shutdown -t3 -r now -a
We currently use pam_console for this sort of shutdown thing, and generally subscribe to the 'those on the console can find a way to reboot anyways' theory. We'll leave this as a modification for local sysadmins.