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%PIX-4-405001: Received ARP response collision

Does anyone have any experience or further explanation of the above/below message other than the system message documentation. I have seen this message being returned with the PIXs inside IP and the MAC address of a server. The server does not have the same IP address as the PIX, but does this mean that the PIX thinks it does?

%PIX-4-405001: Received ARP response collision from 10.0.6.1/000b.xxxx.xxxx on interface inside

(where 10.0.6.1 is the ip address on the pix inside interface and 000b.xxxx.xxxx is the MAC address from a Server).

PIX-OS is 6.3(3)

1 REPLY

Re: %PIX-4-405001: Received ARP response collision

Hi,

This message just means that we received an ARP request from the a machine with the MAC address of 000b.xxxx.xxxx claiming that he was 10.0.6.1. The PIX barks about this because we know that we are 10.0.6.1 and our MAC address differs from 000b.xxxx.xxxx. I have no idea why your server might be doing this. Is there anything odd loaded on this server? Perhaps some sort of sniffing tool? Has this maching been compromised in some way and is trying to fool the internal network into thinking that he is actually the default gateway for the network? Just a few thooughts but you may want to do some investigating on this.

Scott

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