Question : VPN Server behind a NAT enabled router

Hello All,
        I want to setup a VPN connection for our intranet. We have SBS 2000 server setup with ISA firewall, The SBS 2000 is connected to the internet using a DSL Router Dlink 504. The Router has NAT enabled on it, and I have Port redirect enabled to forward port 1723 to the SBS2000 server. I am able to connect and test the VPN from within our network but I am not able to connect to the VPN from outside our network. Why I try to connect to the VPN Server from outside our network, the Windows XP client hangs on login screen, and keeps on saying that its authenticating the username and password. How can I get the VPN running from outside out network, what needs to be done to enable the VPN access with the current setup.

Answer : VPN Server behind a NAT enabled router

Ok, Another check. It appears your Dlink 504 is not capable of doing GRE. The only option you would have is placing the VPN machine in the DMZ.

The only other option would be when you do not want to do this is to replace the router with one that does GRE

goodluck
Ray