How to exclude users from appearing in the GDM login screen of Gnome 3?
There is a long-time bug related to this ( https://bugzilla.redhat.com/show_bug.cgi?id=723708 ) which causes that the
/etc/gdm/custom.conf has no effect.
The closes workaround I find working on Fedora 20 is to totally disable listing of users (run as root):
cat > /etc/dconf/db/gdm.d/01-mysettings <<EOF [org/gnome/login-screen] disable-user-list=true EOF rm /etc/dconf/db/gdm dconf update