Windows 2000 Broadcast Address

Posted on 2003-10-29
Last Modified: 2010-03-19
We are currently tweaking the security in our organization (as the previous IT managers have been rather incompetant).  The company has unix and windows computers.  

The current IT manager wants to be able to sit at a Unix machine, type in the command "ping -b" and be able to grep out the IP address for each Windows 2000 machine on our network.  In other words, he wants all of the Windows machines on our network (mostly 2000) to respond to a ping to the broadcast address.

Does anyone have any input for me?

Thanks in advance,
Question by:rabi9634
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LVL 35

Expert Comment

ID: 9646490
the ping command addresses a single machine. If you want to have a list of all W2K clients, have a look at your WINS or if installed DNS server (as I assume that you have one for the W2K clients) and export this list.

Author Comment

ID: 9650266
I think I should rephrase this a bit..

I want to be able to sit at a UNIX machine that is on the company domain, and type in the command:

ping -b

And have ALL existing machines on the network respond.  Currently, there are some Windows machines that do not respond to this command.. ie, if you were to type

ping -b | grep 115

The IP address would not be listed.    

What do I need to change on the Windows machine w/ the IP address so that when I type in the command:

ping -b | grep 115
there will be an entry returned to show that the address is responsive.

LVL 35

Expert Comment

ID: 9651072
I'm not quite sure what your intension is, but try to ping first the target machine directly. Either the system responds or not. If the system responds, this is not a windows issue. If not, it may be that either the default broadcast address on this machine has changed or there is a router or firewall between the computers which will not route broadcast / ICMP traffic.

To check the broadcast address on the W2K machine, type

route print

at command promt. Within the routing table, you can also see the unicast and broadcast addresses.

Note: neither the switch -b nor the grep command is supported by W2K machines, but this should have nothing to do with that.

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Author Comment

ID: 9651787
That's actually touching on the problem..

If you type "ping -b | grep", nothing comes up.  However, simply entering the command "ping" will generate a response.  

I'm trying to make it so that the .215 IP address will respond to the ping -b command.

(I'm acting solely on the boss's wishes)
LVL 35

Expert Comment

ID: 9652724
That means, your ping reaches the target system and the systems responds. In general there is only the possibility to respond or not to respond as only an empty package comes back as Acknowledgement. Everything else is handled by your source system.

Try the following: Shut down all machines execpting yours and the system, which makes trouble. If your send send a

ping -b

I am quite sure, that the system will respond.

Another idea, have a look at the network setting of this client, TCP-IP Properties - Enhanced, there is a setting NetBios over IP, which should allways be enabled. Additionally, compare the setting on working and not working systems. But as the client responds to direct ping, i guess this is not the option.

Author Comment

ID: 9652976
That's not a feasable option.. i'm in a big company.. shutting down everything just isn't gonna happen.

My thing is, if you type in the ping -b command to the broadcast address, some windows machines will reply, and some will not.  I am looking to change whatever settings I need to change so that ALL windows machines will reply to a ping to the broadcast address.

LVL 35

Expert Comment

ID: 9653403
I am quite sure, dependend on the number of clients, you address with your ping, that the problem is not the response of the clients, as you can see, the client respond to a dedicated ping, I think that the lack is an overlay of multible responses, so that the sending host mmay be not able to handle all the responses at a time. If I make a broadcast ping to my network, I get no response from any W2K computer, only from switches and printers. Have a look if the responding clients have a different service pack.

Author Comment

ID: 9658312
Ok, speaking with some Unix gurus.. this came up.

What I am trying to do in Windows would be achieved by the following in Unix:

ifconfig eth0

where eth0 is the adapter name and is the broadcast address.  All I want to do is set the broadcast address on the Windows machines so that when you type in

ping -b

from a Unix console on the same network as the windows pcs, there will be responses from the windows pcs.  
LVL 35

Expert Comment

ID: 9658633
Type at the DOS promt (windows)

route print

you should see there a route like ...
and ...

The x.255 is the default broadcast address of windows as long it is not changed. If your route print shows something else, you have to change it back to the prefered value (as any clients within a network should have the same)

The Settings for the broadcast address can be changed at

W2K and above:
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\<ID of Adapter>
UseZeroBroadcasts = 0/1
0: uses 0 Mask (=0) as Broadcast address
1: uses 1 Mask (=255) as Broadcast address

or you can use DHCP to set the broadcast address

Accepted Solution

louis_gonz earned 200 total points
ID: 9659469
I have a response to this question.  
1)  I believe an entry of all 1's or all 0's in the registry is not the answer rabi9634 is looking for
     setting the entry to all 1's or all 0's means that when you issue this from the command line:
    all windows clients with the respective registry entry will reply to that as their broadcast address.
   after you issue the above mentioned ping, you can follow by issuing:
    arp -a  
   and this will show you a list of all hosts/clients that responded to their broadcast setting.  So in conclusion, I believe that rabi9634 is looking for the IP address in binary to use as the registry entry, so that those hosts/clients will repsond to that network's CORRECT IP broadcast address.  This is how it works in networking, be it UNIX or Windows or MAC's the CORRECT IP broadcast address for un subnetted class C address is:
x.y.z.255  or x.y.z.11111111  
x = is the binary rep of the first octet
y = is the binary rep of the second  octet
z = is the binary rep of the third octet....
So it should be the case that:
11000000.00001001.01000110.11111111 should be the correct setting for the IP broadcast address in the IP network:
try this and see what happens when you issue the ping -b from your machine!

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