Questions about ARP

Dan Malek dan at
Wed Aug 13 01:39:30 EST 2003

Steven Scholz wrote:

> Windows is checking for duplicate addresses using ARP packets with
> source _and_
> destination address set to the address in question. So of course Linux
> won't answer it!
> But I can't find a single word in the RFC2131
> (
> saying that the Source Address _must_ set to!!!!

I don't remember if it was in RFC2131 or RFC1541.  RFC2131 is an updated
version of RFC1541, so I thought the words would still be there.  In
any case it suggests as part of a DHCP the client tests to ensure the
address isn't already in use by sending a ARP using the sender hardware
address and setting the sender IP address to zero to avoid confusing
ARP caches in other hosts on the network.  I don't remember the exact
words, but RFCs tend to be terse and concise in the area where you
need to pay attention to detail :-)

I'd suggest using the linux kernel or some networking mailing lists
to discuss this.  I wouldn't apply this patch because it seems to be
wrong in the eyes of the RFCs, and I could never get it pushed into
the network portion of the source tree.


	-- Dan

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