Q:

How do I transform a LAN subnet to another? (VPN)

I've set up a VPN with a LAN behind it.
VPN : 10.2.1.X
LAN : 192.168.1.X
When I connect from outside where the router via DHCP assigns me a similar IP to my "original LAN" (192.168.1.X) everything starts to be messed up. I can't route my traffic through the VPN and (obviosly) I can't reach my "real" LAN behind my VPN. How can I always reach my LAN? I thought that I can fake my LAN subnet to something like "10.2.2.X" to those PCs out of my VPN but in this way my VPN server should translate 10.2.2.X to 192.168.1.X (locally).[Is this S/D-NAT?] Is this possible? How can I accomplish that?
Thank you very much!

A:

If your client LAN and the destination LAN are using the same network addresses, you're in trouble.  It can be overcome with some bi-directional NAT, but it's a very ugly hack.
A much easier solution would be to use different networks on each end of the VPN.  Change one or the other, it doesn't matter.

