Essential NetTools Help Documentation

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NBScan is a NetBIOS Scanner, a powerful and fast tool for exploring networks. NBScan can scan a network within a given range of IP addresses and list computers offering NetBIOS resource sharing service as well as their name tables. Unlike the nbtstat utility supplied with Windows, this tool provides a friendly, graphical, user interface and easy management of the lmhosts file and features parallel scanning, which allows checking a class C network in less than 1 minute. Both Class C and B networks can be scanned. NBScan can facilitate routine tasks often carried out by system integrators, administrators, and analysts.


Before you start scanning, you should enter the starting and ending IP addresses in the Starting IP and Ending IP fields as shown above. You may also want to specify the number of simultaneous connections and the connection timeout in the Tasks and Timeout fields. You can sometimes enable the Advanced Mode (see the description below). Click Start to begin scanning.

When NBScan detects a computer that offers NetBIOS resource sharing within the set range, the information about the computer is added to the list. The Name, Workgroup, IP Address, and MAC address columns are self-explanatory. The RS, or Resource Sharing column, is used to assess whether the computer offers resource sharing: Some computers may not be configured to share resources; however, they respond to NetBIOS queries and are listed.

Left-clicking on a listed computer displays its name table in the lower window. If you have a problem interpreting name tables, you can take a look at the NetBIOS Table reference included in this help file.

Right-clicking on a listed computer brings up a menu with the following commands:

· Open Computer – attempts to open the selected computer. If the computer is accessible, a new Windows Explorer window with remote resources will appear.
· Add Item to LMHosts - adds a record associated with the selected computer to the lmhosts file in the appropriate format.
· Add All Items to LMHosts - adds records associated with the listed computers to the lmhosts file in the appropriate format (computers that have no shared resources are not added).
· Copy IP Address – copies the selected computer's IP address to the clipboard.
· Copy MAC Address – copies the selected computer's MAC address to the clipboard.
· Send To – sends the selected IP address to other tools or to SmartWhois.
· Copy Results – copies the NBScan table to the clipboard.
· Save – saves the NBScan table to a file.

Advanced Mode

Because of some peculiarities in handling NetBIOS connections, a small percentage of computers can send replies to queries only to port 137, no matter from which port the query was sent. The advanced mode allows you to choose whether you want the program to receive replies sent to port 137. To switch to the advanced mode, select the Advanced mode (bind to local port 137) box. The advanced mode may not be available if the computer has logged on to the network. If the computer has already logged on, this menu item is disabled. If you want to use this mode, you should turn it on BEFORE logging on to the network. For example, if you use a dial-up connection to the Internet, you should first launch the program, and then check Advanced mode (bind to local port 137), and then dial-up.

Important: Using the advanced mode can influence the operation of some of the Windows network services bound to port 137, e.g. you might not be able to use nbtstat or connect to remote computers. In order to restore the normal operation of such services, you should turn off the advanced mode, log off the network, and log on again.

The reason for these limitations is simple: There is only one port 137 on any system, and it is "owned" by the process that claimed the port first. If Essential NetTools was the first to bind to this port, the program can operate in the advanced mode, but the OS is unable to use it. If the OS binds to it first, then Essential NetTools cannot use the same port. Please remember that this mode is just an advanced feature, and you may not need to use it. In fact, it's quite probable that you will not notice any difference between the results obtained with the advanced mode turned on or off.