On a Fedora 19 system which I set up for somebody a while ago I noticed that no authentication is required when commands are executed as the superuser. So, for example, when running Yum Extender, configuring the firewall or running some command with sudo in the terminal, I am not asked to provide a password. (With graphical applications the authentication dialog pops up for a few milliseconds.) For better security I would like to disable this automatic (authentication-less) assumption of superuser privileges. I do not remember if or how I enabled this authentication without a password. I might have enabled it for convenience for the non-pro user of this machine, but did not do any "fancy" things (like editing config files) to do so. I did not edit the sudoer file. I just checked that. I might have checked a "Do not ask for password again" checkbox or something similar. Whatever I did, I would like to undo it and enforce authentication for superuser tasks again.