Re: [LARTC] Proxy Arp with same left/right IP address.

[Ard van Breemen <ard@telegraafnet.nl>]

On Wed, Feb 13, 2002 at 11:00:35AM -0500, Adrian Chung wrote:
> On Wed, Feb 13, 2002 at 04:52:09PM +0100, Ard van Breemen wrote:
> > The theory behind it: the IP protocol driver needs to be bound to the
> > device. This is done by giving any (bogus) ip address to an interface.
> > Only after the IP protocol driver is bound to the interface you can use
> > it for IP.
> > /proc/sys/net/ipv4/conf will only show interfaces bound to the IP
> > protocol... :)
> > 
> > Of course: you cannot reach the firewall, and the firewall can't reach
> > you. You need a non-bogus ip address for that... (Hmmmm: ssh 127.0.0.1
> > .. Hah! I hacked the firewall.... shutdown -h now ... Uh? ;) )
> Is this for real?  So you bind 127.0.0.1 to both eth0 and eth1, not
> using an ISP assigned IP at all on the bridging box, and you'd still
> be able to route from the ISP's network through to machines on the ISP
> assigned network?
Be careful however, you don't want to send icmp_host_unreachables with
source ip 127.0.0.1, I don't think they get far.
Anyway, 127.0.0.1 is as far as I know a special adres, also for the
kernel. I haven't experimented with that...
If you want to have any sane outgoing source ip addresses, you also
have to set the default source ip for the outgoing routes.

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