This is a boolean option that controls whether connections with usernames not in the user list will be allowed. By default this option is disabled so that a client can supply a username to be used by the server. Enabling this parameter will force the server to only use the login names from the user list and is only really useful in share level security. Note that this also means Samba won't try to deduce usernames from the service name. This can be annoying for the [homes] section. To get around this you could use user = %S which means your user list will be just the service name, which for home directories is the name of the user. user no