Re: [lwip-users] Help with PPP connection - modem disconnects for no obvious reason...

[Sylvain Rochet]

Hi Freddie,

On Wed, Mar 20, 2019 at 07:37:27PM +0100, Freddie Chopin wrote:
> On Wed, 2019-03-20 at 13:20 -0400, Patrick Klos wrote:
> > For whatever reason, you're not responding to the CHAP challenges.
> 
> I assume this is because my user and password are just `""` (empty
> strings), but this is just my very wild guess.

I don't think so, CHAP packets are huge and if PPP_USE_PBUF_RAM is not 
set and your PBUF_POOL_BUFSIZE is a low value then packet allocation 
will fail (lwIP PPP stack does not support chained pbuf), this is my 
wild guess about what is happening.

Null secret is allowed in CHAP. See `secret_len = 0; /* assume null 
secret if can't find one */` from chap-new.c.

Anyway, PAP does not need big packets, and you should try PAP 
authentication with a null login and a null secret. Why compiling the 
somewhat huge CHAP support when this is just fake authentication
anyway ? :)

Sylvain

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