Detected conflict by ARP response (configuration error?)

RouterOS General
1

Hello,

951G-2HnD, typical setting (DHCP, NAT)
In the logs I periodically see

Detected conflict by ARP response for Y.Y.Y.Y from xx: xx: xx: xx: xx: xx

where Y.Y.Y.Y is a host somewhere in the provider’s network

Do I understand correctly that there is a configuration error somewhere, since the router receives an ARP response from the provider’s network?

Help with "Detected conflict by ARP response for" error
2

Go to IP>ARP if the same IP is on a different MAC then that is the issue. Either change or delete from ARP table.

It means you have a statically assigned ARP assigned and another client trying to update the same arp.

Deleting statically assigned IPS from ARP table may not allow pinging.

3

Thanks for the answer,
I checked, mac address xx:xx:xx:xx:xx:xx is not present in the arp list of the router, also, there are no duplicates

4

Hello riwer,

are there no duplicates of the MAC or have you also checked the ip address.
I would recommend to start some pings to the mentioned IP address right before the check.
It is possible that you have IP address is double assigned.

If you have a pubic ip range from your ISP, check that you all addresses are are free.
Sometimes the ISP use one address of this range as gateway for your connections.

5

I will try to describe in more detail

I am using the range 192.168.1.0/24 on my local network and Y.Y.Y.Y = 192.168.173.1

The tracert command from a windows host on the local network reaches 192.168.173.1 in the seventh step (I repeat once again, this is a host somewhere in the local network of the provider)

There is neither 192.168.173.1 nor xx: xx: xx: xx: xx: xx in the arp list of my router (even when I ping 192.168.173.1 from the router)

And I don’t quite understand if it is the norm for a message like

Detected conflict by ARP response for 192.168.173.1 from xx: xx: xx: xx: xx: xx

in the logs of my router or this indicates an error in the router configuration in terms of security

6

I get this also often on may sites and im 100% sure there is no static IPs because its all served and reserved by mikrotik DHCP it self.
I even get this few times a day on hotspot controlled by mikrotik hotspot controller, i doubt ppl put random static IPs on their phones..

Its just mikrotik issue..

7

Hello,

I found this article http://forum.mikrotik.com/t/error-in-log-detected-conflict-by-arp-response/135833/1 which describes the same error massage.
I am not sure if this could be helpful, because it describes, that the error is raised by the Mirkrotik-DHCP-Server, but the point

There’s a device configured with proxy-arp and acts for addresses which it should not

by mkx
could possible a cause of the error, even if it is on a other device.
In the original post, a IPv6 address response to a IPv4 query, so perhaps…