Gratuitous ARP

Alex Bligh alex at
Mon Feb 17 21:11:55 UTC 2014

On 17 Feb 2014, at 18:59, Ted Lemon wrote:

> On Feb 17, 2014, at 1:56 PM, David Peterson <davidp at> wrote:
>> That is exactly the issue.  The wireless device uses proxy arp and responds
>> on the MAC address of the client which causes the NAK  to occur.  I am
>> looking to shut off the DHCPDECLINE functionality in this circumstance.
> Ah.   No, you have to shut off proxy ARP on the wireless device.   There's no way to shut ARP off on the client.   We had the same problem with some wireless devices at Nominum a couple of years ago.   Really vexing!   :}

It's a while since I looked at the proxy ARP RFC, but I /thought/ you were
not meant to proxy ARP for IP addresses that you would reach through the
same interface you received the ARP request on. Else a device with
proxy ARP on would ARP for everything on its subnet. This suggests
this is misconfigured proxy ARP, for instance sharing a L2 broadcast
domain with proxy ARP on, but not having all IP address ranges configured
(and hence reaching some of them through a default route).

Alex Bligh

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