spelth on "Authenticating new/existing accounts with LDAP"

I thought about it, you're right. It is much more simpler, after the code review of the external_auth.php i understand the principals of the user handling a little bit better, that was the missing link.
I think, i only have to change the "return NULL;" in the external_auth.php and make a few changes in my ldap-Plugin to get it working.
Thanks for the hint, my approach was a little bit more complex.
I will post here again when i'm finished.