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Re: [lwip-users] IP forwarding to/from PPP working for one netif, but no
Re: [lwip-users] IP forwarding to/from PPP working for one netif, but not another
Fri, 14 Feb 2020 13:07:26 +0100
On Tue, Feb 11, 2020 at 11:47:04AM +0100, address@hidden wrote:
> Am 11.02.2020 um 10:20 schrieb Andrew Pullin:
> > [..]
> > The part that I am stuck on presently is that Host2 has no knowledge of
> > how to route packets from PPP out to the WAN, say, 188.8.131.52.
> > Between ip4_forward, IP_FORWARD, ip4_route_src, LWIP_HOOK_IP4_ROUTE,
> > LWIP_HOOK_IP4_ROUTE_SRC, and the ESP32 port modifications, I am not
> > quite sure where to make the right intervention. It is ... a lot to take in.
> > As far as I understand the standard usage of the stack for a single
> > netif, outgoing packets elide the entire forwarding/routing system
> > because they are specified to be transmitted on a particular netif? Is
> > that right?
> > Fundamentally, I only have eth0 and pp1 (to use the lwip netif naming
> > system) and anything not specifically with IP dest = eth0 or pp1 should
> > be sent on towards Host2's gateway (after NAT source address IP rewriting).
> > Is that logically complete, and if so, where should it be implemented?
> I would think you'd just set the ppp netif as default netif (so it is
> just used for all outgoing trafic where no better route is found) and
> keep eth0 without a gateway (which should ensure only matching subnet
> packets are transmitted on this netif).
Yes, but the default netif (default route) must be set on eth0, not pp1 :)
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