Re: proxy arp issues

From: Vikram (vvikram@stanford.edu)
Date: Thu Mar 21 2002 - 15:22:48 EST


> Linux will not proxy arp for an address on interface X if the route for
> that address points back to interface X (That's what you call a routing
> loop). Do have have a host-specific route for the address that points
> somewhere else? If you want to use iptables REDIRECT target to capture
> the traffic, then I think a simple "route add -host b.stanford.edu dev
> lo" will work.

one sec...i dont think i gave you the full details.

i understand your point about the routing loop. my method is something
like this:

yes a.stanford.edu does proxy arp for b.stanford.edu though there is no
route setup etc

however i want to use NAT/iptables and DNAT the packet which comes into
the interface [because of the proxy arp] and tunnel it via another
interface to a new destination .

of course the tunnel is setup properly and in general the DNAT works
but the packet never seems to come because there never seems to be a
arp-reply from the comp

hope i was clear.
        Vikram

>
> Vikram wrote:
>
> >Hi,
> >
> >I am having trouble using proxy arp with RH7.2 [linux 2.4.7-10 stock
> >kernel which comes with it]
> >
> >Proxy arp doesnt seem to work. I have hosts a.stanford.edu and
> >b.stanford.edu on the same subnet. b.stanford.edu is no longer there, and
> >a.stanford.edu is set to proxy arp for it....so that it can get its
> >packets [for a specific reason which is not so relevant here,hopefully].
> >
> >i set the proxy arp entry in a.stanford.edu as follows:
> >
> >arp -Ds b.stanford.edu eth0 pub
> >
> >and then ping b.stanford.edu from some host outside. a tcpdump shows the
> >gateway router doing an arp who-has b.stanford.edu but there is no arp
> >reply at all from a.stanford.edu ??
> >
> >can anyone tell me what i have missed ?
> >
> >
> > Vikram
> >
> >-
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> >
>
>
> --
> Casey Carter
> Casey@Carter.net
> ccarter@uiuc.edu
> AIM: cartec69
>
>
>
> -
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