DMZ and VPN

[Security Manager]

I've been following the thread on FTP servers in the DMZ with interest. I'm curious as to how it applies to a server providing VPN access using Win2k Server's Routing and Remote Access.

Given that the VPN is supposed to give access to the private network to external clients (who can authenticate) how can you avoid having at least one interface on the local network? Surely the best you can do is have one interface on the private network, and the other in a DMZ (behind the firewall) - but you've still the problem if the VPN provider is compromised!

How do you solve that one?

TIA - SecMan.