[pptp-server] Windows XP and ACCMs possible problem.

[Dougal Holmes]

Chris

I did have a similar problem with a Win2000 client which insisted on trying
to negotiate ipsec as well as PPTP. The result was that it appeared to
connect, but there was no data flow.

To fix this, I specifically disabled ipsec in the dialup connectoid, and
enabled pptp and high encryption (128 bit) only.

Then we used the CMAK to setup a custom connectiod, and tweaked the .inf
settings to ensure Windows _never_ tried to negotiate ipsec.

Dougal Holmes (at home)
mailto:dholmes at bigpond.net.au

----- Original Message -----
From: "Chris Kennedy" <ckennedy-poptop at iland.net>
To: <pptp-server at lists.schulte.org>
Sent: Tuesday, November 06, 2001 7:42 AM
Subject: [pptp-server] Windows XP and ACCMs possible problem.


> We cannot get a PPTP connection in Windows XP to pass
> data, it will connect but just be a dead link.  The odd
> thing I notice is that the logs say...
>  'CTRL: Ignored a SET LINK INFO packet with real ACCMs!'
> I then modified the code to print out the SET_LINK_INFO
> fields values, which were 'send_accm = 0 recv_accm = ffffffff'
> and it says this in the code if they aren't both 0xffffffff.
> I can see in the RFC that this setting can set other options
> for the connection, which seems to have not been used in
> Microsoft Clients until XP (and seems to be a Win2000K patch
> that gets it into this broken state too).  I am not sure where
> to go with this, maby someone with much more knowledge of
> this on the list can see more into what this all means, maby
> this is just another error, and something else is broken in
> XP's PPTP support.  It seemed to work for users with XP betas,
> up until the final release, where it broke first.  Also another
> interesting thing is if you setup 40bit encryption only on the
> PPTP server, it barely works, like a few lines of the HTTP headers
> then the packets stop, just a dribble of a connection.  We are using
> the following (tried it on poptop1.0.1 too)...
>
> PPTP PopTop 1.1.2
> Linux Kernel 2.4.2
> PPPD 2.4.0
>
> Thanks,
> Chris
> --
> Chris Kennedy / ckennedy at iland.net / (660) 829-4638x117
> I-Land Internet Services / Network Operations Center
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