[plug] Routing problem with PPTP VPN

[Simon Fryer]

Evening All

> A while ago Leon Brooks tapped:

> On Saturday 09 February 2002 16:45, Jeremy Malcolm wrote:
> > Perth's gateway machine can ping Kalgoorlie fine over the VPN and vice
> > versa. All of the machines on Perth's network can ping the Internet fine
> > over IP Masquerading.  But, none of the machines on Perth's network apart
> > from the gateway can ping Kalgoorlie over the VPN.

A couple of questions, can the gateway machine ping all the kalgoolie machines
or just the single machine at kalgoolie? I am assuming you have network at
kalgoolie. 

> It would probably help to use something other than 192.168.0.* for the VPN 
> link itself. Try 192.168.234.[12] for the link ends. Windows in particular 
> gets confused if you have (for example) some of 192.168.0.* on a LAN and 
> other parts non-local because it tries to take short-cuts and gets it wrong. 
> LJBC ran into this.

This is good advice. I can't remember the complete set if IP reserved addresses
off the top of my head but as a general rule, I would have avoided the 
192.168.0.0/24 subnet. Perhaps reconfigure with the 192.168.2.0/24 network 
although, I don't think this will improve anything if you are running a pure 
linux machines. I find IP on linux to a cludge that works when it really 
shouldn't.  

The other thing I would do would be to run routed or something equivilent to
route between the ppp1 and eth0 interfaces (from memory ppp1 is the virtual ppp
link to Kal) unless you are sure you need masquerading between these 
interfaces. Routed will probably need to be run at both ends of the link. 

Have you been playing with tcpdump and traceroute to see where the packets go
or end up? Both are excellent tools to debugging network problems. 

I can't say I have a lot of experiance setting routing up over VPN's but this 
is where I would start looking. 

Good Luck. 

See Ya
Simon

-- 
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"Well, an engineer is not concerned with the truth; that is left to 
philosophers and theologians: the prime concern of an engineer is 
the utility of the final product."  
Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh