We are looking for a clarification of ASA nat-control command. Unfortunately, we don't have spare device to test it out.
The situation is as follows:
An ASA firewall has three interfaces: "inside", "outside", and "corpinside".
nat-control is DISABLED.
A GLOBAL statment is defined on the "outside" interface and the correpsonding NAT statement on the "inside" interface, something like:
global(outside) 1 ...
nat (inside) 1 ...
We confirmed packets from "inside" to "outside" are allowed even for the packes that do not match any NAT rules (including Static NAT, DynamicNAT, and NAT Exempt).
The issue is what happens to traffice from "inside" to "corpinside" if no Dynamic NAT is defined from "inside" to "corpinside" and two interfaces have
different secuity levels.
One interpretation is: Since NAT is disabled, all traffic from "inside" to "corpinside" should be allowed.
Another interpretation: If dynamic NAT is configured on an interface, all traffic from that interface to any other interface must hit a NAT rule, therefore traffic from "inside" to "corpinside" should be denied .
We need a clarification of which interpretation is correct.
Also,if "inside" and "corpinside" are at the same security level, then is the traffic allowed?