I am using Gnome 3 with Debian Wheezy. I am looking for a way to make the user ask at least for the root password when using the shutdown button from the menu.
polkit/consolekit can do exactly what you need. Write a new polkit rule:
add the following content (assuming you require root password for both shutdown & restart):
[Disable shutdown/restart] Identity=unix-user:* Action=org.freedesktop.consolekit.system.stop;org.freedesktop.consolekit.system.restart ResultAny=no ResultInactive=no ResultActive=auth_admin
Change the privileges on the shutdown command in /sbin so that only root (or a member of a group with equivalence) can execute it. You would make the changes via chmod or the file-manager of choice in your distribution. If you did this, in theory you would have to "sudo shutdown -h now" and you would be prompted for the root password. That should work in theory
Another more complicated but better answer:
Step1: Open /etc/X11/gdm/gdm.conf in a text editor and find the [greeter] section. Make sure that there is a line which says SystemMenu = false. This line will ensure that the gdm login screen will not have the option for shutting down the system etc. Step 2: If you have a laptop, or an acpi system on your computer, then go to /etc/acpi and disable the power button, so that, when someone presses the power button, the system does not shutdown. You can disable this easily by doing chmod 000 /etc/acpi/powerbtn.sh Step 3: Now edit /etc/inittab and find the lines that say: #Trap CTRL-ALT-DELETE ca::ctrlaltdel:/sbin/shutdown -t3 -r now And change it to read: #Disallow CTRL-ALT-DELETE ca::ctrlaltdel:/bin/echo “ctrl-alt-delete has been disabled” . This will effectively prevent users from changing to a console screen and using ctrl+alt+delete to shutdown the system. Step 4: Execute the following commands: sudo chgrp admin /sbin/halt /sbin/shutdown sudo chmod 550 /sbin/halt /sbin/shutdown Step 5: Use the Configuration Editor (Applications -> System Tools -> Configuration Editor) to edit the preference apps->gnome-session->options->logout_opt… to “logout” instead of “shutdown”. Now only a superuser (Admin) can shutdown the system, using the command: $sudo shutdown -t3 -r now
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