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

[Chris Kennedy]

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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