pptp win2k sp4 error 650 and 721

[scott]

Hi,

PPTP connections appear to have stopped working again (has been working for
2 years prior to sp4)

Reffering to KB 271731 (PPTP clinets cannot connect to a PPTP server......)

- i have 2 nic, one is now removed
- i amended registy to include ValidateAddress on pptp adapters and set
DWORD to 0

One line in this article suggested the following:

"to resolve this issue, configure the firewall or the router so that the
source of the PPTP reply packets is the same IP address that the PPTP
clinets use"

I dont understand what this section is saying. How to i configure the SOURCE
of the PPTP reply (my vpn server) to be the same IP address that the clinets
use ?

MY SETUP
The router and firewall allows incoming PPTP ports 1723 and GRE port 0
(protocol 47).

net
..
..
192.168.0.1
router
192.168.2.1
..
..
192.168.2.50
firewall
192.168.1.25
..
..
192.168.1.199
VPN server

PPTP and GRE are forwarded to appropriate port.

Thanks
Scott.

 

[scott]

Got a better test:

NET
v
ROUTER
v
ROUTER > win2k clinet (WS012)
v
FIREWALL
v
RAS SERVER

- The win2k clinet (WS012) on the middle router (DMZ) can ALWAYS establish a
PPTP connection to RAS SERVER.
- This connection passes through the FIREWALL.
- Once this connection has been made all other external PPTP WIN2k clients
can connect.
- After WS012 disconnects and after several mins all external WIN2k that
attempt connection get error 721.

What the heck is going on ?

Thanks for any information at all.
Scott.

 

[scott]

futher testing showed:

win98 on external ip connect ok (firewall report PPTP 1723 + GRE)

win 98 manually disconet, reconnect (frewall report PPTP 1723 only)

Its like GRE was lost during the second connection. IE second time GRE did
not make it as far as the FIREWALL.

Im checking middle ROUTER.