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 From:  Paul Dugas <paul at dugas dot cc>
 To:  m0n0wall Mailing List <m0n0wall at lists dot m0n0 dot ch>
 Subject:  PPTP MTU Problem
 Date:  Sat, 15 Apr 2006 14:04:13 -0400
Did some more digging into my PPTP problems this morning.  I think I may
have come up with something to go on.  Some background first...

At home:
  [laptop] <-> {home} <-> [m0n0-1.21] <-pppoe-> {ISP} 

At work:
  {office} <-> [m0n0-1.2] <-> {dmz} <-> [netopia] <-pppoe-> {ISP}

I'm using WinXP running in a VMWare session on my FC5 laptop.  I'm
trying to connect a PPTP VPN connection from the WinXP virtual machine
to the office network.  The virtual machine is setup to use a bridged
network on the laptop so I am able to run Ethereal and capture the
traffic.  A pcap file is attached.  It is the traffic between the
virtual machine and the office m0n0 machine.

I'm no PPTP expert but I think I'm seeing the WinXP initially request an
MRU of 1400.  Then m0n0 responded with an offer of 1600 which was
rejected.  m0n0 responded with another offer of 1500 which was also
rejected.  This repeated a couple more times with 1500 then the WinXP
machine gave up.  

So, am I reading this right?  If so, how do I tell the PPTP server on
m0n0 to accept the lower MRU value?  I'm dying for a fix to this.  Any
suggestions would be appreciated.

Paul Dugas, Computer Engineer                Dugas Enterprises, LLC
paul at dugas dot cc        phone: 404-932-1355     522 Black Canyon Park
http://dugas.cc        fax: 866-751-6494     Canton, GA 30114 USA
On site at GDOT's W.Annex, 404-463-2860 x199
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pptp.pcap.gz (1.8 KB, application/x-gzip)
signature.asc (0.2 KB, application/pgp-signature)