Strange VPN problems

[Rick Jones <rick activeservice co uk>]

I've never been able to get NM to make a successful VPN connection, and I finally have some meaningful (I hope) logs etc.

I can get a working connection using pppd with pptp on the command line, but not using NM. It seems that the NM plugin sets up the connection slightly differently. This command line works (executed as root):

/usr/sbin/pppd pty '/usr/sbin/pptp server.my.domain --nolaunchpppd' nodetach lock usepeerdns noipdefault refuse-pap refuse-chap refuse-mschap require-mppe nobsdcomp nodeflate name rick

(auth is handled by chap-secrets in normal way)

The server is another Linux box, so the connection is served by pppd + pptp on the remote end as well. In particular the server log shows the server responding to client PPTP echo requests at 1 minute intervals:

pptpd[2289]: CTRL: Received PPTP Control Message (type: 5)
pptpd[2289]: CTRL: Made a ECHO RPLY packet
pptpd[2289]: CTRL: I wrote 20 bytes to the client.
pptpd[2289]: CTRL: Sent packet to client
... etc

When I create the connection with NM, no PPTP echo messages are received, instead the server attempts to send the echoes, but gets no response. This kind of thing appears after about 2 minutes:

pptpd[31784]: CTRL: Sending ECHO REQ id 1
pptpd[31784]: CTRL: Made a ECHO REQ packet
pptpd[31784]: CTRL: I wrote 16 bytes to the client.
pptpd[31784]: CTRL: Sent packet to client
pptpd[31784]: CTRL: EOF or bad error reading ctrl packet length.
pptpd[31784]: CTRL: couldn't read packet header (exit)
pptpd[31784]: CTRL: CTRL read failed
pptpd[31784]: CTRL: Client 89.193.143.54 control connection finished
pptpd[31784]: CTRL: Exiting now

 - connection gone.

(Note this is not LCP echo - that's disabled already)

NM appears to be setting up the connection differently, in a way that doesn't work - what's the difference?

Is there anything I can do server-side to make it more friendly?

I'm running the current PPA build of NM on Ubuntu Hardy 8.0.4. Has anything changed in this area in rc1?

-- 
Rick