PPTP, newnat and masquerading not working

[Hampus Soderstrom <hampus.soderstrom@aptilo.com>]

Hi,

I want to use PPTP behind a masquerading router but I have problems 
getting it to work.

This is how I install masquerading PPTP:

1. I upack a vanilla kernel-2.4.20
2. I patch with newnat
(http://roeder.goe.net/~koepi/newnat/helpers-2.4.20.patch.gz)
3. I do a make menuconfig and add PPTP and GRE Proto support
4. I install iptables v1.2.7a
5. I do the rest of the kernel building (make dep && make modules && 
make modules_install && make bzImage).
6. I fix my lilo and reboot with the new kernel.
7. I add masquerading with iptables:
iptables -I POSTROUTING -t nat --jump MASQUERADE
8. I add portforwarding (/proc/sys/net/ipv4/ip_forward)
9. I modprobe ip_nat_pptp and verify that ip_nat_pptp and 
ip_nat_proto_gre is loaded with lsmod.


Now I have a setup that looks like this:

PPTP Client1 ===> Masquerading Router ===> PoPToP Server
PPTP Client2 ===>

8. I start upp pptp in a win2k machine (Client1) I get:
error: 619 The specified port is not connected and error 651.

I have verified that masquerading works for http and that pptp works if 
I bypass the Masquerading router.

What have I overlooked in getting it to work?


/Hampus