In Palo Alto Networks firewalls, the processing of NAT rules occurs in a top-down fashion, similar to security policies. To exclude a specific IP address from a broader source NAT rule, a more specific NAT rule must be placed above the broader rule.
C: Place a more specific NAT rule above the broader one:
* Create a source NAT rule (NAT-Rule-1) to translate the broader network range (10.0.0.0/23) with dynamic IP and port translation. This rule allows the majority of the subnet to access the internet through NAT.
* Create another NAT rule (NAT-Rule-2) with the source IP address in the original packet set specifically to the IP address that should not be translated (10.0.0.10/32). In this rule, set the source translation to none, indicating that this traffic should not be translated and thus not allowed to access the internet.
* Place NAT-Rule-2 above NAT-Rule-1 in the NAT policy list. This ensures that the more specific rule (NAT-Rule-2) is evaluated first. If traffic matches NAT-Rule-2, it will not be translated or allowed to the internet, effectively excluding the specific server from internet access.
This configuration leverages the principle of specificity and the order of operation in NAT policies to exclude a specific IP address from source NAT translation, thereby preventing it from accessing the internet.