I've been doing some research on this topic, and I'm asking for some help. I have a VPN tunnel I'm trying to set up to a remote network (that I have no control over). However, that remote network has used all private IP addresses. Meaning that I cannot assign my network any private IP addresses to use over the tunnel. I need to do NAT on a completely different IP address across the tunnel. I need the far end of the tunnel to see an address other than the private address which is assigned to the machines on this end. So rather than disabling NAT across the tunnel, I need to ENABLE NAT over the tunnel, but I need it to be a NAT to a completely different IP than the one I have set up on the external interface for doing PAT out to the internet! I hope I've explained this well enough and someone out there can help me. Thanks.
I have this problem too.