In many installations of Samba, the greatest threat comes from outside your immediate network. By default, Samba accepts connections from any host, which means that if you run an insecure version of Samba on a host that is directly connected to the Internet, you can be especially vulnerable.

One of the simplest fixes in this case is to use the hosts allow and hosts deny options in the Samba smb.conf configuration file to allow access to your server only from a specific range of hosts. An example might be:

The above will allow SMB connections only from localhost (your own computer) and from the two private networks 192.168.2 and 192.168.3. All other connections will be refused as soon as the client sends its first packet. The refusal will be marked as not listening on called name error.