Re: [Poptop-server] Win XP SP3, Vista and VPN

[James C. <jam...@hp...>]

On Tue, Jun 17, 2008 at 09:28:58AM +0200, Martin Hochreiter wrote:
> The ping packets are never reaching the server altough the GRE packets
> do

Wrong.  The ping packets were in the GRE packets reaching the server,
but the ping replies were not.

> I am far away from knowing how pptp/ppp VPN really works but my
> "explanation" is that the connection is correctly established the GRE
> packets are traveling correctly from client to server and back, but
> the content of the GRE packets (with XP SP3) is somehow not correct
> ... the ip packets are truncated. Maybe I am completely wrong, if so -
> please tell me.

Yes, you're wrong.  Please re-read what I said and do the tests I've
suggested, in particular find out whether the ping reply packets are
seen on the tunnel network interface, not the interface over which the
tunnel runs.

Your tcpdump text output is consistent with the tcpdump binary data you
provided.  The packets aren't truncated, as far as wireshark was
concerned, perhaps you need to include -s 0 on the command line to avoid
that bogus report.

> How should I go on to debug the problem (lsof and strace?)

In what respect?

On Tue, Jun 17, 2008 at 09:39:12AM +0200, Martin Hochreiter wrote:
> I tried another thing that I learned from an older thread of you:
>
> I disabled "require-mppe-128" and suddenly it works with XP SP 3 ... I
> don't want to make tunnels without encryption but this is a step
> further.  Is the ubuntu 8.04 mppe packet not working or at least not
> working with SP 3?

Good point, perhaps you need to do something to the client around the
vicinity of encryption and compression options.  Properties of
connection or something.  I don't recall.

Have a look at
http://poptop.sourceforge.net/dox/diagnose-forwarding.phtml for a
customisable diagnosis procedure ... it doesn't quite fit your problem,
but it will help you understand what is meant to happen.

-- 
James Cameron                         http://quozl.netrek.org/
HP Open Source, Volunteer             http://opensource.hp.com/
PPTP Client Project, Release Engineer http://pptpclient.sourceforge.net/