Dirty NAT tricks

[Tiago Cruz]

Hello guys,

Following this link: http://www.nimlabs.org/~nim/dirtynat.html
I learn that I can do some "dirty NAT trick" with my firewall to make
this:

"You have a corporate LAN. You want to set up a VPN (in this case
OpenVPN) into the LAN for your road-warriors. However, your LAN is
numbered with one of the very common private subnets, such as
192.168/16. Your road-warriors often get addresses in the same private
subnet from their coffee-shops, and this breaks things horribly."

So.. How can I manage the PREROUTING and POSTROUTING rules in PF?

iptables -v -t nat -A PREROUTING -d 192.168.8.0/24 -j NETMAP --to 10.22.8.0/24
iptables -v -t nat -A PREROUTING -i tap0 -d 10.22.0.0/16 -j NETMAP --to 192.168.0.0/16
iptables -v -t nat -A POSTROUTING -o tap0 -s 192.168.0.0/16 -j NETMAP --to 10.22.0.0/16
iptables -v -t nat -A POSTROUTING -o eth0 -s 10.22.0.0/16 -j NETMAP --to 192.168.0.0/16

Thank you!
-- 
Tiago Cruz
http://linuxrapido.org