I'm a network administrator at a company. We are currently having a problem with people downloading a valid list of usernames from our webserver. I ran a network security program called Retina, and it says they are going through Netbios. I'm wondering how they are doing it. I know you can use a program like Retina, but i wondering if there is a way they are doing it through just code on a webpage or some other way/program besides one such as Retina.

Any help would be greatly appreciated