When installing and configuring Microsoft Windows hosts, such hosts are allocated names which are used with the NetBIOS protocol to identify shared resources on those hosts.
The firewall can use these names as a form of user authentication. This is a very weak form of authentication, since users can change the names of their hosts. Nevertheless, it can be useful in controlled environments, especially where there are multiple client hosts that use dynamic IP address assignment and that are each associated with a single user. The main use for NetBIOS authentication is for logging and accounting/reporting.