One method to detect duplicate IPs is to use SNMP to query your routers
every 4 hours for the ARP entries. (ARP times out every 4 hours in a cisco
router) We use the CMU snmp package to do the queries. Then put the info
into a database and query the database for duplicates. We have a system
like this with a web interface and also some scripts that scan ths
database daily for duplicates and e-mails notices to people in charge of
the relevant subnet.

  The code is somewhat rough, so I do not want to offer it to the
net-at-large. If you can not find a polished product, e-mail me and I'll
share more aobut this solution.


> Alittle off subject but does anyone out there know of some SW that detects
> duplicate IP addresses?
> Scott

I think you are searching for arpwatch. Source can be found at

It needs libpcap to run but that can be found also at this location.

Have fun,