netdev - RE: ebtables on a stick

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Message-ID: <925A849792280C4E80C5461017A4B8A2A0488A@mail733.InfraSupportEtc.com>
Date:	Mon, 28 Nov 2011 08:54:09 -0600
From:	"Greg Scott" <GregScott@...rasupport.com>
To:	"David Lamparter" <equinox@...c24.net>
Cc:	<netdev@...r.kernel.org>
Subject: RE: ebtables on a stick

> This doesn't answer your question, but your use case is better solved
> with proxy arp.

Proxy arp scares me to death.  I lived through a disaster a few years ago when I messed up a whole colo site when I put in a box with its public NIC set up with Proxy arp.  If I understand what happens, that proxy-arped NIC answers ARP requests for everyone with its own MAC Address.  Fortunately for me, it only lasted a little while around 4AM one morning before I realized what was going on and took it down.  After I went through that experience I promised myself never again for proxy arp.

That's why I started looking at bridging.  

...But maybe there's a way to make my NIC only answer ARPs for certain IP Addresses I care about?  That would nicely solve the problem.  If it works.  

In my earlier near-disaster, I did this:

echo 1 > /proc/sys/net/ipv4/conf/${INET_IFACE}/proxy_arp

to turn on proxy arp.  I wonder if that ip neighbor stuff does it selectively?  

- Greg