utility that scans lan for client?

[John Almberg]

On Mar 23, 2009, at 3:19 PM, David Kelly wrote:

> On Mon, Mar 23, 2009 at 02:59:36PM -0400, John Almberg wrote:
>> I've tried googling for this, but I guess I don't know the name of a
>> utility such as this...
>>
>> What I'm looking for is a utility that can scan a LAN for attached
>> clients... i.e., computers that are attached to the LAN.
>>
>> I have one box (an appliance that I have no access to), that is on
>> the LAN but I don't know what IP address it's using. I'd like to
>> complete my network map, and that is the one empty box on my chart.
>
> How about something as simple as "arp -a"? This lists the arp cache of
> machines recently heard by your machine. If you know the IP address of
> the machine in question and its not in your arp table, ping it.  
> Then the
> MAC address will appear unless there is a router between here and  
> there.
>
> No need to be root.

H'mmm. This is also very interesting.

nmap did not find this appliance, as it turns out. But arp -a did  
found something on 192.168.1.107 (see below)

server1 (192.168.1.106) at 0:13:d4:45:45:31 on en1 [ethernet]
server2 (192.168.1.107) at (incomplete) on en1 [ethernet]
server3 (192.168.1.108) at 0:23:12:f8:5e:fd on en1 [ethernet]

I'm guessing this appliance (a Vonage phone adapter) is doing  
something non-standard.

-- John