I have a server 2003 box with 2 nics setup for VPN and NAT. I went the second nic route to get past a 3rd party controlled firewall in our setup that is managed by an outside companys that wants big bucks just to open a few ports.
The lan nic has a static assigned of 184.108.40.206, subnet .128 and no gateway set.
The wan nic is set with a static also and has the gateway info for our isp.
Computers outside of this network are able to connect on the wan nic and access any computer on the network BUT the computers on the network are not able to communicate. ping or anything back.
The VPN server has no firewall enabled that I have configured or am aware of.