I have a 2851 Router. I am in the process of setting up a VPN. I have already created the ACL for my VPN interetsting traffic but, need to know how to disable NAT for my traffic going accross the site to site VPN?
In the acl that you're using for natting, deny the subnets that you're pushing across the vpn.
Suppose you have 192.168.1.0/24 and 192.168.2.0/24 on the other side. You want to nat 192.168.1.0 when it goes to the internet, but you don't want to nat across the tunnel.
ip nat insid source route-map NAT inte s0/0
access-list 100 deny ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255
access-list 100 permit ip any any
route-map NAT permit 5
match ip address 100
Only traffic included on the ACL will be candidate for NAT.
If you don't want some flows to be NAT'd, don't include them on the NAT ACL.
NAT 0 is FW is for NAT exception. Not needed on Cisco IOS as traffic not included on the NAT ACL has an exception by default.
Don't include that traffic on the ACL