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 From:  Didier Lebrun <dl at quartier dash rural dot org>
 To:  m0n0wall at lists dot m0n0 dot ch
 Subject:  RE: [m0n0wall] PPTP
 Date:  Wed, 07 Jan 2004 13:16:57 +0100
At 11:44 07/01/2004 +0100, Magne Andreassen wrote:
>Brandon Holland wrote
> >
> > Does M0n0wall's pptp server work with windows clients?  Or
> > should I redirect all pptp connections to my main office
> > server and from there authenticate everyone?
> >
>Windows clients works, though there have been some trouble
>with XP and packet loss. But I don't think everyone has had
>this problem.

I do have these problems with a gateway between a 802.11b LAN and a 
bidirectionnal sat link in a remote village in south west of France ! The 
802.11b LAN is quite lossy, since some clients are far away (up to 2 km), 
with trees and partial interferences with a military radio station 
nearby... and I have all kind of clients, including WinXP ones.

I was actually investigating these problems on my own with a fully featured 
FreeBSD system when I saw your message. When measuring the loss on the 
802.11b LAN with iPerf, I get between 0,2% and 5% loss, depending on the 
weather (wind mainly, because of the trees) and the military radio station 
emitting or not. I have some out of order packets too. The WinXP problem 
seems to be independant of the lossy link problem, since it keeps on 
behaving poorly, even when connected directly on the hub with ethernet 
wire. Beside that, my problem is a bit complexified by the use of RFC 1323 
options, since the [bandwidth * latency] product of the bidi sat link is 
too high for standard TCP (TCP RWIN goes up to 120 KBytes and jitter can be 
up to 500 ms).

I have already got a satisfying solution though, with PPPoE (user-PPP) 
instead of PPTP (mpd), both with lossy links and with WinXP. I found out 
that disabling the "speed sync" option in ppp.conf was making the 
difference with PPPoE and lossy links, but haven't found any similar 
solution yet with mpd's PPTP. My first guess for the WinXP problem was 
MTU/MRU issues, but I tried all kinds of setting without any success :-(

I would be grateful to you if you had some hints to spare about these problems.

Didier Lebrun
Le bourg - 81140 - Vaour (France)
mailto:dl at vaour dot net (MIME, ISO latin 1)