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Date:      Thu, 31 Jul 1997 18:37:05 -0500
From:      Gabor Kincses <gabor@acm.org>
To:        Greg Lehey <grog@lemis.com>
Cc:        archie@whistle.com, hackers@FreeBSD.ORG
Subject:   Re: PPP chap problem
Message-ID:  <33E121A1.7432@acm.org>
References:  <199707312241.IAA07609@freebie.lemis.com>

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Greg Lehey wrote:
> 
> Gabor Kincses writes:
> > Archie Cobbs wrote:
> >>
> >>> I have tried to make chap work, but no go.  I have used pap and no
> >>> authentication for over 6 months now, but chap doesn't seem to work.
> >>>
> >>> I always get
> >>> LCP:  SendConfigRej(Req-Sent)
> >>>  AUTHPROTO proto = c223
> >>>
> >>> which means that my side rejects chap authentication.
> >>> Even though I added enable chap, accept chap.
> >>
> >> Enable chap means "i want the peer to authenticate to me using chap",
> >> so you don't want to do that.
> >>
> >>> I also tried to disable chap and only accept chap, but that didn't work
> >>
> >> Hmm, should have.
> >
> > I understood what enable chap meant after reading someone's post on the
> > newgroup and tried out disable chap and accept chap, which didn't work
> > either.  The really interesting part is that if I say accept pap, then
> > the SendConfigRej becomes SendConfigNak AUTHPROTO proto = c023, so it
> > seems there might be something wrong with the chap state in the
> > code.
> 
> No.  PAP is 0xc023, CHAP is 0xc223 (see net/ppp_defs.h).

I know.  I looked (actually also defined in /usr/src/usr.sbin/ppp). 
What I meant here is that with accept or deny pap, my side refuses to
accept chap.  When pap is allowed (accept pap) my side suggests the use
of pap instead of chap (since maybe it thinks chap is not allowed, which
would be the hypothesized bug, since I DID accept chap), hence the
SendConfigNak AUTHPROTO proto = c023 message.  When pap is not allowed
(deny pap) it sends a SendConfigRej AUTHPROTO proto = c223, attesting
that it (ppp) thinks that chap is in fact disallowed.  Whether pap is
denied or accepted should really be irrelevant to the chap discussion,
except in both cases I see indication that ppp thinks chap is not
allowed on my side, in spite of the explicit 'accept chap'.

I haven't read the RFC, but it seems logical that it would try to use
pap as a fallback, if chap is denied.

> 
> > Again I'm getting this after I escape out of term into packet mode.  Is
> > there anything different here from executing a script?
> 
> Well, yes.  I don't understand the question.

I meant that people have gotten chap working a zillion times fine.  The
only thing that seems non-standard in my case is that I need to enter
term to answer the SNK challenge number and then enter packet mode from
there.  I felt that most people use the scripting method to dial up
their providers.

> 
> > I only have the 2.1.5 source code, but haven't been able to dig through
> > the relevant portions.  All I can tell that the code never really gets
> > into the chap.c stuff...
> 
> That seems unlikely.  Have you done a complete trace?  There's nothing
> you've shown here which disproves Archie's suggestion, which I think
> is correct.
> 
> Greg

I looked at the code where the log messages are written to the log file
(based on what I have found in the log file itself) and concluded that
ppp thinks that chap is not allowed, so it never goes into trying to
perform chap.  Ie. when a SendConfigRej AUTHPROTO = c223 message is
written to the log file, you have not yet done chap and you never will. 
Is this last assumption wrong?

-- 
Gabor Kincses
(gabor@acm.org)
FreeBSD 2.1.5/2.2.2



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