[CentOS] How to restrict reboot/poweroff from non-admins?

Wed Mar 28 13:17:16 UTC 2012
Timo Neuvonen <timo-news at tee-en.net>

I just noticed that CentOS (6.2) by default allows any user to 
reboot/poweroff system without any admin rights, or without any further 
questions, if using commands 'reboot' or 'poweroff'. But 'shutdown' still 
requires admin rights.

What is the preferred way to restrict any regular user from rebooting / 
powering off the system (by accident)?

IMHO, sudo should be required for this purpose (at least in a system with 
shared remote access from multiple users, single-user laptops etc may be a 
different case)