ANNOUNCEMENT: Live Wireshark University & Allegro Packets online APAC Wireshark Training Session
April 17th, 2024 | 14:30-16:00 SGT (UTC+8) | Online

Wireshark-users: Re: [Wireshark-users] Duplicate use of IP detected

From: Soju Master <sojumaster@xxxxxxxxx>
Date: Sun, 6 Jun 2010 12:55:06 -0400
I do have a few systems in my network that have teaming NICs, I will have to check it when I get to work tomorrow. 
 
I am suspecting that it might be teaming NIC's based on the very simular NIC addys:
 
Duplicate IP address detected for 10.0.1.181 (00:22:19:80:72:79) - also in use by 00:22:19:80:72:7b (frame 4515)
Duplicate IP address detected for 10.0.1.180 (00:22:19:80:75:35) - also in use by 00:22:19:80:75:37 (frame 4566)
 
Another thing that I did notice though, when I first ran the scan at work, I had about 200 or so frames, in the live scan, complaining about the duplicate use of an IP.
When I saved the scan and looked at it at home, only two frames had the error message.  Is this normal for Wireshark?
 
Thanks


 
On Sun, Jun 6, 2010 at 9:22 AM, Ian Schorr <ian.schorr@xxxxxxxxx> wrote:
If you can see two MAC addresses claiming to be the same IP address
(and therefore dupe IP situation), you can follow the CAM/MAC tables
in your switch to specifically locate the ports the two systems are
connected to.

If you suspect a duplicate IP address situation, filter on
"ip.addr==<IP address>".  See if it's immediately obvious that there
are two systems sharing the same IP.  If not, filter one out by adding
" && !eth.addr==<mac address of the system that you can see in the
trace".  You may want to add an "&& arp" as well.  If there's truly
another MAC claiming to be that IP address, you should see it here,
and be able to track down the ports of the two MACs.

If the MAC addresses are very similar (i.e. first 5 bytes are the
same, or otherwise differ by a value of 1 or so) then there's a good
chance that you're dealing with a teaming NIC.

-Ian

On Sun, Jun 6, 2010 at 1:48 AM, Jaap Keuter <jaap.keuter@xxxxxxxxx> wrote:
> Hi,
>
> Teamed network interfaces, maybe?
>
> Thanks,
> Jaap
>
> On Sat, 5 Jun 2010 10:13:40 -0400, Soju Master <sojumaster@xxxxxxxxx> wrote:
>
> I was running a scan and started to notice these summaries:
>
> AsustekC_ad:e3:e7     Dell_80:75:35     ARP     10.0.1.35 is at
> 00:1a:92:ad:e3:e7 (duplicate use of 10.0.1.180 detected!)
> Dell_9d:29:af     Dell_80:72:79      ARP      10.0.1.230 is at
> 00:23:ae:9d:29:af (duplicate use of 10.0.1.181 detected!)
>
> I have done the obligatory research to see if there is a duplicate IP on the
> network and could not find any.
>
> Anyone know what this message means?
>
> Thanks
>
>
>
> ___________________________________________________________________________
> Sent via:    Wireshark-users mailing list <wireshark-users@xxxxxxxxxxxxx>
> Archives:    http://www.wireshark.org/lists/wireshark-users
> Unsubscribe: https://wireshark.org/mailman/options/wireshark-users
>             mailto:wireshark-users-request@xxxxxxxxxxxxx?subject=unsubscribe
>
___________________________________________________________________________
Sent via:    Wireshark-users mailing list <wireshark-users@xxxxxxxxxxxxx>
Archives:    http://www.wireshark.org/lists/wireshark-users
Unsubscribe: https://wireshark.org/mailman/options/wireshark-users
            mailto:wireshark-users-request@xxxxxxxxxxxxx?subject=unsubscribe