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Re: [2.4 PATCH] bugfix: ARP respond on all devices

To: Carlos Velasco <carlosev@xxxxxxxxxxxx>
Subject: Re: [2.4 PATCH] bugfix: ARP respond on all devices
From: David T Hollis <dhollis@xxxxxxxxxxxxxx>
Date: Sun, 17 Aug 2003 12:51:01 -0400
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>, Lamont Granquist <lamont@xxxxxxxxxxxxxxxx>, Bill Davidsen <davidsen@xxxxxxx>, "David S. Miller" <davem@xxxxxxxxxx>, bloemsaa@xxxxxxxxx, Marcelo Tosatti <marcelo@xxxxxxxxxxxxxxxx>, netdev@xxxxxxxxxxx, linux-net@xxxxxxxxxxxxxxx, layes@xxxxxxxxx, torvalds@xxxxxxxx, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>
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Carlos Velasco wrote:

On 17/08/2003 at 16:28 Alan Cox wrote:



Linux doesn't issue "bad" requests. Linux will reply when it is
asked for an address that it owns, as per RFC826, unless you chose
to change the behaviour with things like arpfilter.



We are not talking about ARP Replies, we are talking about ARP Requests. You can see the Richard post here, same issue I reported several weeks ago: http://marc.theaimsgroup.com/?l=linux-net&m=106094924813337&w=2

==
        On eth0, we see:

11:23:55.650514 0:4:75:ca:c4:ef Broadcast arp 42: arp who-has
10.10.10.1
tell 212.xxx.yyy.9
==

Linux is sending an ARP Request to a LAN where the source IP address of
the packet has not any sense in that IP network.
And, at least, 2 RFCs are stating that other devices should not reply
to this packet. Currently know Cisco, Foundry; possibly others, and
possibly others coming as ARP storms are not desired.

Regards,
Carlos Velasco


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Check out: http://www.linuxvirtualserver.org/docs/arp.html. I understand the problem you're talking about. It's not a 'bug', it's a feature! You need to use the hidden interface approach to have the back end system not broadcast it's MAC for the virtual IP.


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