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Date:      Mon, 18 Mar 1996 16:33:56 -0500 (EST)
From:      Frank Seltzer <frankd@yoda.fdt.net>
To:        freebsd-questions@freebsd.org
Subject:   Re: [Linux-ISP] PPP 2.2.0e (fwd)
Message-ID:  <Pine.BSF.3.91.960318163046.182A-100000@Kryten.nina.com>

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This was sent to me by my ISP regarding my problems after he upgraded his 
PPP (Linux)

Frank

---------- Forwarded message ----------
Date: Mon, 18 Mar 1996 00:15:55 -0500 (EST)
From: Jon Lewis <jlewis@inorganic5.fdt.net>
To: frankd@gnv.fdt.net
Subject: Re: [Linux-ISP] PPP 2.2.0e (fwd)

Here's a message I just got back about the freebsd-linux PPP problem.

---------- Forwarded message ----------
Date: Sun, 17 Mar 1996 20:21:42 -0800 (PST)
From: Al Longyear <longyear@netcom.com>
To: Jon Lewis <jlewis@inorganic5.fdt.net>
Cc: linuxisp@lightning.com
Subject: Re: [Linux-ISP] PPP 2.2.0e

Jon Lewis wrote:
> 
> I just upgraded my terminal server from PPP 2.1.2 to PPP 2.2.0e, and 
> suddenly a user using FreeBSD 2.2.0-stable can no longer use PPP to 
> connect to the terminal server.  Anyone seen anything like this or know 
> where the problem is?
> 
> He claims to be using pppd 1.1.6.1 dated 3-1-96.

A couple of users of PPPD version 2.2 have expressed similar 'problems'.

The problems seem to come from the fact that the PPPD code is sending a
CCP frame.

According to the PPP specifications (RFC 1661, section 5.7), the frame
is to be rejected if the protocol is not known. This means that the
fact that you received the unknown protocol frame is to have
absolutely no difference on any other protocols which may be going on
at the same time.

However, there seem to be several versions of PPP out there which
totally freq out when they receive this unknown frame type. They
simply balk at the frame and just get totally lost.

The pppd process is following the RFC documents in that it sends the
CCP options. The peer system (FreeBSD-stable) is not.

You can do one of three things:

1. Tell the FreeBSD user to use pppd version 2.0, version 2.1, or
   version 2.2 and not the ijjppp that is commonly used with FreeBSD.

2. Get the user to fix ijjppp so that it follows the standards and
   does not become confused over the issue.

3. Edit the Linux pppd driver so that it does not take up the CCP
   layer. This means that it will never use CCP, but it also means that
   it wont send the frame which causes the broken clients, such as
   ijjppp, to become confused.

If you wish to change pppd, edit the main.c file and comment the call
to open_ccp. In addition, you need to comment the entry in the
prottbl[] list so that the pppd process will not recognize the CCP
protocol. Don't do just one change or you will end up with a 'broken'
implementation of PPP.

-- 
Al Longyear            longyear@netcom.com            longyear@sii.com
Finger longyear@netcom.com for PGP public key.

 




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