computers on network

Is there software which will detect computers on a physical network?
Discovering new computers on the same subnet would be a start.
Can it alert an administrator to the existence of the new computer?

Why is it that whenever I do a ping broadcast of a subnet (with more
than 40 computers) I don't get a reply from a large number of them. In
some cases I have noted which computer doesn't appear to be replying and
pinged it seperately and then I get a reply.

On Sat, 21 Feb 2004 20:04:37 GMT, Philip Washington wrote:

> Why is it that whenever I do a ping broadcast of a subnet (with more
> than 40 computers) I don't get a reply from a large number of them. In
> some cases I have noted which computer doesn't appear to be replying and
> pinged it seperately and then I get a reply.

Maybe the boxes are setup to not respond to broadcast pings.

On Sat, 21 Feb 2004 20:04:37 GMT, Philip Washington
<(E-Mail Removed)> wrote:

> Is there software which will detect computers on a physical network?

Yes, nmap will do that. There are lots of other ways too.


> Why is it that whenever I do a ping broadcast of a subnet (with more
> than 40 computers) I don't get a reply from a large number of them.

That is probably on purpose. Think about what happens if someone pings
the broadcast address of a large network using a spoofed source address
that belongs to a third party.


--
-| Bob Hauck
-| To Whom You Are Speaking
-| http://www.haucks.org/

On 2004-02-21, Bob Hauck <(E-Mail Removed)> wrote:
> On Sat, 21 Feb 2004 20:04:37 GMT, Philip Washington
><(E-Mail Removed)> wrote:
>
>> Is there software which will detect computers on a physical network?
>
> Yes, nmap will do that. There are lots of other ways too.
>
far easier is to look at the dhcpd leases file and more so the current ARP
table, if there are any 'unauthorized' changes then they can be easily picked
out and the MAC address completely blocked.

Alex