14.4.  Samba Security Modes

User-level security is the default setting for Samba. Even if the security = user directive is not listed in the smb.conf file, it is used by Samba. If the server accepts the client's username/password, the client can then mount multiple shares without specifying a password for each instance. Samba can also accept session-based username/password requests. The client maintains multiple authentication contexts by using a unique UID for each logon.

In smb.conf, the security = user directive that sets user-level security is:

[GLOBAL]
...
security = user
...

[GLOBAL]
...
security = user
...