Currently NAT is enabled bidirectionally between OUTSIDE & INSIDE.
If I am configuring NAT exemption for hosts on the outside interface, will NAT 0 command be applied only to outside interface or even inside.
Nat exemption should take precedence over all forms of NAT. Are you trying to exempt addresses as they go from inside to outside or outside to inside.
Also after adding the nat exempt rule did you clear xlate on any existing translations for those hosts ?
I am trying to exempt both ways - bidirectionally across two interfaces i.e. INSIDE and OUTSIDE. How would the NAT exempt configuration be in this case.
Yes, I did clear xlate while testing.
Okay, NAT exemption should be bi-directional.. Try this config instead
nat (inside) 0 192.168.5.10 255.255.255.255
nat (inside) 0 192.168.5.11 255.255.255.255
Are you suggesting identity nat over nat exemption. If so, why is that.
Please explain why is it only applied to inside interface only and not outside and how will it serve bi-directionally.
"Are you suggesting identity nat over nat exemption. If so, why is that"
No, the first solution i gave was just more complicated than it needed to be (i do that sometimes !).
All you want is to just exempt 2 host addresses from NAT so the second example i sent is simply that - 2 nat exemptions.
It only needs to be applied to one interface because it is bi-directional. If it wasn't bi-directional then yes you would need to apply it to both interfaces.
I have tried all the above after clearing specific xlate entry but no success. I will mention my example again
DMZ (Interface) : Security Level 75
OUTSIDE (Interface) : Security Level 0
NATing (bi-directional) is enabled for all hosts on OUTSIDE subnet (10.10.10.0/24) when communicating over DMZ interface. NATed network is 18.104.22.168/24. Now, I would like to exempt 10.10.10.50 and 10.10.10.51 from being NAT'ed to 22.214.171.124 and 126.96.36.199.
The current static NAT entry on FWSM is
static (OUTSIDE,DMZ) 188.8.131.52 10.10.10.0 netmask 255.255.255.0
I have tried this as well. It defaults to classful subnet i.e. 10.0.0.0 / 16 with nat 0 command. The xlate gets populated with the NAT'ed global and actual local. NAT exemption is not taking place.
Sorry, that should have been
nat (DMZ) 0 10.10.10.50 255.255.255.255
nat (DMZ) 0 10.10.10.51 255.255.255.255
Edit - if the above stil doesn't work then the next thing to try is nat on the outside interface ie.
nat (outside) 0 10.10.10.50 255.255.255.255 outside
nat (outside) 0 10.10.10.51 255.255.255.255 outside
The NAT issue is still not solved. I have tried both the suggestions above still the same. I then used a sniffer to verify that NAT'ing is still taking place from and to these hosts and not exempted. Seems complicated.