[pptp-server] PPTP masquerade

[Josh Howlett]

Would it be feasible to modify the behaviour of poptop so that it
behaved like MS RAS?  This would be really really useful.

tia, josh.


On Fri, 22 Jun 2001, robert wrote:

>   The PPTP RFC specifies in section 3.1.3 that there may only be one
>   control channel connection between two systems. This should mean that
>   you can only masquerade one PPTP session at a time with a given remote
>   server, but in practice the MS implementation of PPTP does not enforce
>   this, at least not as of NT 4.0 Service Pack 4. If the PPTP server
>   you're trying to connect to only permits one connection at a time,
>   it's following the protocol rules properly.  Note that this does not
>   affect a masqueraded server, only multiple masqueraded clients
>   attempting to contact the same remote server.
> 
> On Friday 22 June 2001 07:11, Josh Howlett wrote:
> > Is this a limitation/feature of poptop?  I've read of ppl doing it with
> > Windows PPTP server.
> >
> > thx, josh.
> >
> > On Fri, 22 Jun 2001, Justin Kreger wrote:
> > > You cannot do that, It won't work.
> > >
> > > Justin Kreger, MCP MCSE CCNA
> > > jkreger at earthling.2y.net jwkreger at uncg.edu justin at wss.net
> > >
> > > On Fri, 22 Jun 2001, Josh Howlett wrote:
> > > > Hi all,
> > > >
> > > > Has anyone managed to masquerade PPTP clients and got them to talk to
> > > > pptpd?  I'm working on the following set-up:
> > > >
> > > >  PPTP client-\
> > > >
> > > >  PPTP client---Masq--(ip)--PPTP server
> > > >
> > > >  PPTP client-/
> > > >
> > > > It works fine for a single PPTP client, but if a second attempts to
> > > > connect to the same server I get this:
> > > >
> > > > Jun 22 10:52:58 cypri pptpd[23386]: CTRL: Client 137.222.12.160 control
> > > > connection started
> > > > Jun 22 10:52:58 cypri pptpd[23386]: CTRL: Starting call (launching
> > > > pppd, opening GRE)
> > > > Jun 22 10:52:58 cypri pptpd[23327]: Discarding out-of-order packet 1,
> > > > already have 216
> > > > Jun 22 10:52:58 cypri pppd[23387]: pppd 2.4.0 started by root, uid 0
> > > > Jun 22 10:52:58 cypri pppd[23387]: Using interface ppp1
> > > > Jun 22 10:52:58 cypri pppd[23387]: Connect: ppp1 <--> /dev/pts/2
> > > > Jun 22 10:52:58 cypri pptpd[23386]: Buffering out-of-order packet; got
> > > > 1 after 4294967295
> > > > Jun 22 10:52:58 cypri pptpd[23327]: Discarding out-of-order packet 2,
> > > > already have 216
> > > > Jun 22 10:52:58 cypri pptpd[23386]: Packet reorder timeout waiting for
> > > > 0 Jun 22 10:52:58 cypri pptpd[23386]: Buffering out-of-order packet;
> > > > got 2 after 0
> > > > Jun 22 10:52:58 cypri pptpd[23386]: Missing 12 consecutive packets; got
> > > > 217 after 2
> > > > Jun 22 10:52:58 cypri pptpd[23327]: Discarding out-of-order packet 3,
> > > > already have 217
> > > > Jun 22 10:52:58 cypri pptpd[23386]: Discarding out-of-order packet 3,
> > > > already have 217
> > > > Jun 22 10:52:58 cypri pptpd[23327]: Discarding out-of-order packet 4,
> > > > already have 217
> > > > Jun 22 10:52:58 cypri pptpd[23386]: Discarding out-of-order packet 4,
> > > > already have 217
> > > > Jun 22 10:53:01 cypri pptpd[23327]: Discarding out-of-order packet 5,
> > > > already have 217
> > > >
> > > > I've read (and followed) the VPN masquerade HOWTO, and it says that
> > > > this set-up is possible assuming the server allow multiple control
> > > > channels to the same IP address.
> > > >
> > > > Does poptop allow this?  Or could I being doing something else wrong?
> > > >
> > > > thanks, josh.
> > > >
> > > > ---------------------------------------
> > > > Josh Howlett, Network Supervisor,
> > > > Networking & Digital Communications,
> > > > Information Systems & Computing,
> > > > University of Bristol, U.K.
> > > > 0117 928 7850 | josh.howlett at bris.ac.uk
> > > > ---------------------------------------
> > > >
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>