/etc/shadow has permissions on 0600, shouldn't they be 0400?
Why? It's owned by root, root can write to 0400 files anyway. The only difference is that vi warns about writing to a readonly file and you have to do :w! instead of :w... I don't see a real advantage in either.
Maybe he was referring to what linuxconf wants to do Changing permissions of file /etc/shadow from 100600 to 100400 Explain to linuxconf that in this case 600 is ok :-)