I post the article here just in case that link won’t work any more in the future
I was looking to enable password-less login on Ubuntu Karmic for my children, so that they could just click their face from the username list to login. I eventually found how to do this on a very old thread on the Ubuntu forums.
In Karmic I noticed an option within Users and Groups “Don’t ask for password on login”, but the option was greyed out. Someone commented on this in bug 396459 on launchpad and mentions adding a group named “nopasswdlogin”. I tried this, and although it did allow me to select the option, the login window (known as GDM) still prompted for a password.
I then came across an old thread from 2005 on Ubuntu Forums, “GDM logging on locally without entering password?”, which I tried and amazingly it still worked. The only difference now is that in Karmic the location of the GDM config file has changed from /etc/X11/gdm to just /etc/gdm.
So here is how my /etc/pam.d/gdm looks, with the lines I added in bold:
auth requisite pam_nologin.so
auth required pam_env.so readenv=1
auth required pam_env.so readenv=1 envfile=/etc/default/locale
# the line below has been added specifically to allow selected users to log in via GDM without a password
auth sufficient pam_listfile.so item=user sense=allow file=/etc/gdm/nopassusers.txt onerr=fail
auth optional pam_gnome_keyring.so
session [success=ok ignore=ignore module_unknown=ignore default=bad] pam_selinux.so close
session required pam_limits.so
session [success=ok ignore=ignore module_unknown=ignore default=bad] pam_selinux.so open
session optional pam_gnome_keyring.so auto_start
And this is my /etc/gdm/nopassusers.txt:-
I then rebooted and my children could login with just one click.