Windows networks use a system of shared files and printers based upon the SMB (Shared Message Block) protocol. This protocol is deployed within the Windows NetBIOS protocol, which in turn, is installed by default over TCP/IP in the first versions ofWindows95 and Windows 3.11 for Group Work.
This characteristic becomes a security problem when systems using Windows networking shares connect to an unreliable network such as the Internet. In such cases, any Internet user can attempt to access the Windows system NetBIOS services remotely through the TCP/IP and access the resources if these have not been adequately protected.
There is the possibility that in certain local network configurations it may be necessary to install NetBIOS over TCP/IP and in order to counteract the security problem, it becomes essential to establish password accesses to all shared resources. This way, a user outside the system will not know the password and therefore will be unable to access such resources from outside the system.
In order to check if you have NetBIOS installed over TCP/IP in your Win9x system, look up its properties in (Start -> Configuration -> Control Panel -> Network -> TCP/IP -> Properties -> NetBIOS tab), where there is a check box that allows you to disable it. This prevents an Internet user from accessing shared resources on the local network. Another way of checking whether we are exporting NetBIOS to the Internet is to launch the command NETSTAT -A (in MS-DOS) and seeif the ports 137, 138 and 139 appear.
In any case it is advisable to install the more recent versions of operating systems, which have as general rule taken care of these types of problems.
Maxwell
