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) -- TiN