OK I understand. Is that the entire configurable portion of the smb.conf file or is there more ?

I cordially suggest that the root-cause problem is probably not Samba, at all.

To my reading of what you're saying, the root-cause issue is that the server is letting anybody in. Samba is presenting itself as an anonymous client ... or it's anonymous because the server isn't bothering to ask it who it is ... and Samba is probably doing the right thing.

If there is a "security issue," then I would suggest that "it couldn't possibly be 'a client issue,' anyhow!" (Hey, if I possessed an SMB-client that could log on without a password to a properly configured, properly secured server, I could make a lot of money with that!)

Yes