If you have duplicate IPs being detected from ARP requests or responses it will because the same IP addresses is seen having two MAC addresses. Once you isolate the two MAC addresses using this IP address, you will want to look at your switch forwarding database (sometime known as MAC address table or CAM table depending on the vendor). For instance on Cisco switches "show mac-address-table" will show you what interfaces the MAC addresses appear on. While your Core switches might show a lot of this on say trunks going to your edge switches, by repeating this process on the connected edge switch you will eventually find the interfaces that directly connect to the offending devices.
Just remember that this could also be due to a misconfigured proxy ARP configuration on a router or also where redundancy say protocols such as VRRP are being used.
Regards, Martin
MartinVisser99@xxxxxxxxx
On Fri, Jun 25, 2010 at 7:10 AM, Josue Del Valle
<jodelvalle@xxxxxxxxxxxxxxx> wrote:
Hi,
I hope someone can help me out with this. I am running
Wireshark from two different computers and getting the same results. Basically
I am getting the following:
ARP/RARP Duplicate IP address configured (192.168.10.222)
ARP/RARP Duplicate IP address configured (192.168.10.220)
ARP/RARP Duplicate IP address configured (192.168.10.208)
This is an example:
154,"16:58:24.071822","Dell_55:3b:5b","Dell_42:b5:3a","ARP","Who
has 192.168.10.40? Tell 192.168.10.222 (duplicate use of 192.168.10.200
detected!)"
These addresses are statically assigned and I don’t
see how they could be duplicated. I read that this could be an ARP attack
but I’m not sure what to look for.
How can I know whether it is an ARP attack and trace the
computer that’s causing the problem.
Regards,
JD
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