[pptp-server] linux pptp -> win2000 connection problems

[Steve Sarette]

I posted a while back that I can connect into my work's Win2000-based 
pptp vpn, but that tcp activity has a frustrating way of hanging with no 
errors posted to my log files.  I still haven't resolved this problem 
but I think I might know what is causing it.  Can anyone confirm the 
following?

 From section 7.3.7 (proxy arp problem) in 
http://www.vibrationresearch.com/pptpd/pptpd-FAQ.txt :


"For routing to work (i.e. to have the local/remote ip addresses NOT
on the same network as the 'protected' network and interconnect the
VPN network and the 'protected' network using routing tables),
the computers on the protected network need to have the linux box
as a gateway"


So here's the setup I'm dealing with (on RedHat 6.2, ppp 2.3.10 with 
ppp-2.3.10-openssl-0.9.5-mppe.patch and 
ppp_mppe_compressed_data_fix.diff, and pptp-linux-1.0.2).  I connect to 
the Win2000 vpn using:

pptp <remote vpn ip address> call work

and /etc/ppp/peers/work contains:

lock
debug
noauth
name <mylogin name>
+chap
+chapms-v2
mppe-40
mppe-128
mppe-stateless
proxyarp
noauth

After successfully authenticating to pptp I see this in /var/log/messages:

local  IP address xxx.xx.9.230
remote IP address xxx.xx.10.254

Even tho xxx.xx are the same, these really aren't on the same subnet are 
they?  Further, most of the remote IPs that I'm trying to connect to are 
of the form:

xxx.xx.0.yyy

which is yet a different subnet, yes?

If I'm correct and these are really all different subnets, then proxyarp 
can't possibly work in this setup, yes?  Please confirm this or tell me 
if I'm all wet.  :)  At the moment, trying to enable proxyarp results in 
not being able to ping the remote network at all.  And this is after 
setting:

echo 1 > sys/net/ipv4/conf/default/proxy_arp
echo 1 > /proc/sys/net/ipv4/ip_forward

and re-establishing the pptp session.

Now, this:

route add -net xxx.xx.0.0 gw xxx.xx.10.254 netmask 255.255.0.0 ppp0

allows me to route my traffic to the remote hosts.  I can ping the 
remote hosts but most other tcp traffic silently hangs (as I've stated 
before).  Is this the symptom that I should expect because the 
"protected network" does not have "the linux box as a gateway?"

Sorry for the long post, but I'm really scratching my head over this one.

BTW, I'm making a BIG assumption here that people can and have connected 
a linux based pptp client to a stock Win2000 pptp vpn.  Can someone 
please confirm that this will in fact work (because they've done it)?

Thanks in advance for your help.  And I'd appreciate any ideas on what I 
could try next (short of purchasing a Win2000 box *shudder*).

- Steve