Is there a way that Cisco IOS can be configured to do conditonal NAT operations?
For example, as a default I want to NAT traffic coming into the router from some private IP space destined for most public space. But if the traffic on the private side needs to talk to some particular address on the public side of the router, such as a DHCP server (by IP address and/or by port), I'd like to keep the traffic un-NAT'ed.
For example:
interface FastEthernet0/0
ip address 1.2.3.5 255.255.255.192
ip nat outside
interface FastEthernet0/1
ip address 10.33.0.1 255.255.0.0
ip helper-address 1.2.3.4
ip nat inside
ip nat pool NAT-POOL 1.2.3.5 1.2.3.5 prefix-length 26
ip nat inside source list NAT-LIST pool NAT-POOL overload
ip access-list standard NAT-LIST
permit 10.33.100.0 0.0.0.255
Let's say I want to send traffic to the DHCP server at 1.2.3.4 coming from 10.33.100.0/24, but I do not want it NAT'ed. Can I play some some of trick to make an exception to the normal NAT'ing rule? I've seen some discussion that this might be done with a route-map statement, but I'm wondering if someone might be able to provide a working example.
Thanks.
Clarke Morledge
College of William and Mary
