Security
This option affects how clients respond to Samba and is one of the most important settings in the smb.conf file.
The option sets the "security mode bit" in replies to protocol negotiations with smbd(8) to turn share level security on or off. Clients decide based on this bit whether (and how) to transfer user and password information to the server.
The default is security = user, as this is the most common setting needed when talking to Windows 98 and Windows NT.
The alternatives are security = share, security = server or security = domain .