Re: [lwip-users] forwarding and NAT

[Marleen Vos]

Hi,

Thank you for the quick response.

Now I know NAT is out of the question, I could put my question in 
another way:

The situation I have in mind is to use an embedded device as a router, 
with ethernet on one end, and serial on the other end (connected to GPRS).
There can be multiple devices connecting over the ethernet link, so the 
forwarding would actually need to be able to work in this situation too.

A connection coming in over the serial link would need port forwarding 
to reach the correct address behind the router. Is that possible with lwip?

Devices making a connection from the ethernet side, have to be forwarded 
to the serial side. Will this forwarding work for multiple devices 
without (stateful)NAT? I would think not, but I'm not sure on this.

Thanks again for your time,
Marleen


On 4/02/2015 15:33, Sylvain Rochet wrote:
> Hello,
>
>
> On Wed, Feb 04, 2015 at 01:48:51PM +0100, Marleen Vos wrote:
> > Hello,
> >
> > I was looking around to see if lwip supports forwarding from PPP
> > (serial) to Ethernet (in both directions),
>
> Yes, it works in the master branch.
>
>
> > and if NAT was possible.
>
> lwIP does not have NAT support, there was a task about it but it didn't
> materialise. NAT is quite hard to do correctly, require huge amount of
> memory (I guess you are actually talking about stateful NAT), and in my
> opinion this is outside the scope of a small IP stack. If you need NAT
> or forwarding I am personally suggesting using Linux on ARM or MIPS SoC,
> Linux have a more-than-comprehensive NAT support with NAT helpers for
> many hard-to-deal-with protocols.
>
>
> > No virus found in this message.
> > Checked by AVG - www.avg.com
> > Version: 2015.0.5646 / Virus Database: 4281/9054 - Release Date: 02/04/15
>
> Thanks, but I don't care.
>
>
> Sylvain



--
Marleen Vos
Embedded Software Engineer
Bausch Datacom NV
Tiensesteenweg 54-56
B-3360 Korbeek-Lo
Belgium
tel. +32 16 461288
fax. +32 16 463151


-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.5646 / Virus Database: 4281/9056 - Release Date: 02/04/15