04-19-2022 09:42 AM - edited 04-19-2022 05:48 PM
We are in the process of implementing a NO NAT configuration on one of our firewalls and are running into an issue.
We have created an object-group for source IPs that will have the NO NAT configuration applied.
object-group network NO_NAT
network-object host 1.1.1.1
We then created a network object that contains the destination - which would be internet based:
object network NO_NAT_DEST
subnet 0.0.0.0 0.0.0.0
nat (inside,outside) source static NO_NAT NO_NAT destination static NO_NAT_DEST NO_NAT_DEST no-proxy-arp
All internet based traffic is routing as expected - no NAT applied. But when traffic destined for a private address routes through the firewall (DMZ destined), the traffic is routed the same as the internet based traffic. This looks to be because the subnet in the NO_NAT_DEST object matches the 0.0.0.0 0.0.0.0 default route.
My thinking is that we implement two separate NAT statements - one that contains an object-group that contains private networks as the destination and one that contains the 0.0.0.0 destination. Configure the NAT for the private destinations first - then configure the NAT for the 0.0.0.0 destination. That way the private destination NAT is processed first and routed accordingly but anything not destined for a private network will be processed by the 0.0.0.0 destination NAT.
Will this work as expected?
What would be the best way to implement this NO NAT configuration?
Solved! Go to Solution.
04-19-2022 10:04 AM - edited 04-19-2022 10:06 AM
@mbrandon32 yes create the more specific no NAT rule first and/or do a route-lookup on the NAT rule.
Route lookup—(Routed mode only; interfaces specified.) Specify route-lookup to determine the egress interface using a route lookup instead of using the interface specified in the NAT command. See Determining the Egress Interface for more information.
04-19-2022 10:04 AM - edited 04-19-2022 10:06 AM
@mbrandon32 yes create the more specific no NAT rule first and/or do a route-lookup on the NAT rule.
Route lookup—(Routed mode only; interfaces specified.) Specify route-lookup to determine the egress interface using a route lookup instead of using the interface specified in the NAT command. See Determining the Egress Interface for more information.
04-19-2022 11:54 AM
@Rob Ingram I missed the route-lookup configuration. Looking into route-lookup in more detail, we should just be able to configure the following:
nat (inside,outside) source static NO_NAT NO_NAT route-lookup
Correct?
04-19-2022 06:38 PM
nat (inside,outside) source static NO_NAT NO_NAT route-lookup did the trick. Thanks!
04-19-2022 11:31 AM - edited 04-19-2022 12:03 PM
config another NO NAT and make it above this NAT by add "1" , and the issue is solve OR config after-auto in NAT which push this NO NAT "0.0.0.0" down to list of NAT.
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