find local computers

Pete Nesbitt pete at linux1.ca
Thu Mar 4 00:18:02 UTC 2004


On March 3, 2004 05:22 pm, Marty Landman wrote:
> At 08:13 PM 3/3/2004, Pete Nesbitt wrote:
> >Looks looks like responding to a broadcast ping, as Keith stated, does not
> >work for Win boxes.
>
> I wasn't clear. I ran the command on my rh9 box from an ssh session on my
> winxp box. The rh box was the only response I got.
>
> > > yes, except I don't know about broadcast addresses
> >
> >you mean you don't understand them or it doesn't work?
>
> I don't understand them. (so can't very say whether it's working or not)
>
> Marty Landman   Face 2 Interface Inc.   845-679-9387
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The broadcast address is the highest IP in the subnet, so on a class C, such 
as 192.168.1.0 (or 192.168.0.0) where there is a range from 192.168.1.0 to 
192.168.1.255, the first IP '192.168.1.0' represents the network as a whole, 
and the highest number '192.168.1.255' is used to 'broadcast' messages to 
every machine.

A system will typicaly accept packets sent to that machine or else to the 
broadcast address. The advantage is that instead of sending out 254 packets 
to 254 IP addresses, you simply send one packet that every machine accepts.

If Microsoft boxes do not answer a broadcast ping (I recall someone telling me 
older versions of MS will reply), and you only have one non MS box (RH), then 
it makes sense only one ping returns (the host system also replies). When 
your system answered the broadcast ping, it tells you that that function 
works as it went to the broadcast address, not the local IP. 

It looks like you need to look thru each IP with your script.

-- 
Pete Nesbitt, rhce





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