I think I answer more questions than I ask here, but now it's my turn - I can't seem to figure out what I should change here, and it don't make no sense to me . I have a samba fileserver. I am not using winbind. I am using NIS for UID/GID lookup. I am using AD via Kerberos for authentication. Also I used "net join" so it's all very well integrated with AD. Normal (non-root) users can simply browse to \\filer <file:///\\filer> and they're automatically authenticated, and all the umasks and UID/GID are handled correctly. However - If Administrator tries to browse to \\filer <file:///\\filer> , then it prompts for username and pass. I enter any combination of "root" or "administrator" or "DOMAIN\username" or "username@domain" and it will never authenticate as administrator - only normal users can connect. While trying to figure it out, I went as far as assigning a new UID (not zero) to the "administrator" user, to make the administrator really remarkably similar to a normal user, and still no luck. I also checked . I have not set anything for "invalid users" or "valid users" Can't think of anything else to try . Any suggestions?