[ale] Slightly OT: Decyphering 'arp' error

[John Mills]

ALErs -

I have a network device that requests a DHCP address assignment on boot. 
It expects and receives a particular address in our subnet. Shortly after, 
it presents the following warning on the system log:

  "arp: 0xc04ac1b4 is using my IP address 172.16.1.160!"

That IP is supposedly reserved against my device's MAC, but apparently 
there is a problem somewhere with the assignment. Presumably the 
'0xc04ac1b4' identifies the hardware which has a conflicting claim to the 
same IP. How can I use that data to help identify the conflicting unit? Is 
there a test I can do to determine if the conflicting unit is responding 
to net traffic? (I think of 'nmap' against the IP and looking for open 
ports my application does not have, but that wouldn't work if the 
conflicting device were similar to mine: it would then present the same 
signature.)

NOTE: The network device is an embedded product based on eCos, using an 
older BSD network stack. The DHCP server is (I believe) Microsoft.

TIA for any pointers.

  - Mills