Re: [lwip-users] Getting Raw ARP Packets

[Jan Menzel]

Hi Dave!
        What you described looks like a bridge to me. If you don't have to
process tcp/udp packets (send an receive data from your local device)
you don't need lwip. You could just build an Ethernet driver (which you
would have to do for lwip anyhow as its hardware related and not part of
lwip) and forward all packets to your host. If you do need to send data
and hence wont to make use of lwips features, I'd suggest to put the
bridge related features into the Ethernet driver and keep lwip
untouched. In that case you'll have to rethink your "My device will not
have an IP address" clause.

        Jan

On 21.05.2018 18:26, David M. Zar wrote:
> I'm somewhat new to using LWIP (version 2.0.3) and am making great
> progress with my application which will include processing raw IP
> packets. One problem is that we also need to accept and pass on ARP
> packets. I don't see an easy way to do this without modifying code in
> etharp.c. Would this be the accepted method?
> 
> Some details... I am creating an application where my device will be a
> "bump-on-the-wire." My device will not have an IP address and will
> accept UDP/TCP packets (in raw mode) from the network and pass them on
> to a host connected at the other side. Likewise, I will accept UDP/TCP
> from the host and pass them on to the network side. I can do that. But I
> also need to handle ARP. When an ARP packet shows up from the network
> side, I need to pass it on to the host who will then respond. That
> response will then need to go back to the network.
> 
> Optionally, I could simply know the appropriate ARP response to send for
> my host and send it as soon as I see an ARP packet with my host's IP
> address, but that's a minor difference. I still need to accept ARP
> packets and process them, myself, and not expect the LWIP stack to do so.
> 
> Thanks for any insights/suggestions you may have.
> 
> Dave
> 
> 
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