You need to modify two files to enable root login via GDM (Gnome Display Manager) which is the default display manager on Debian 6. First edit /etc/gdm3/daemon.conf and add the following line: AllowRoot=true under the security options i.e. under the [security] tag. Then comment out the following line in /etc/pam.d/gdm3 auth required pam_succeed_if.so user != root You should then be able to login as root via GDM.
A YubiKey is an ingenious hardware authentication token that looks like a very small USB memory stick, but actually acts as a type of USB keyboard. With the touch of a button, a YubiKey can send a time-variant, secure passcode as if it was typed in from a keyboard. Since USB keyboards are supported by most computers the YubiKey works on the majority of platforms and browsers without the need for any client software. The YubiKey was invented in 2006 by Stina and Jakob Ehrensvärd and first sold to the public in 2008. Since then it has gone through a