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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
Tue, 11 Feb 2020 11:47:04 +0100
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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, 18.104.22.168.
> 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).
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