NAT and Global commands.

Basically there is no more global command, and we are now a lot more reliant on object groups.

If you are port forwarding (Static PAT) then the dns re-write will no longer work.

NAT 0 (or no nat) no longer exists.

OLD – Regular PAT – 1 External IP to many internal IP addresses

nat (inside) 1 0 0
global (outside) 1 interface

NEW – Regular PAT – 1 External IP to many internal IP addresses

object network obj_any
subnet 0.0.0.0 0.0.0.0
nat (inside,outside) dynamic interface

OLD – Static PAT (Port Forwarding)

access-list inbound extended permit tcp any interface outside eq smtp
access-list inbound extended permit tcp any interface outside eq www
access-list inbound extended permit tcp any interface outside eq 3389
static (inside,outside) tcp interface www 10.254.254.5 www netmask 255.255.255.255
static (inside,outside) tcp interface smtp 10.254.254.5 smtp netmask 255.255.255.255
static (inside,outside) tcp interface 3389 10.254.254.5 3389 netmask 255.255.255.255

NEW – Static PAT (Port Forwarding)

access-list inbound extended permit tcp any object obj-10.254.254.5 eq smtp
access-list inbound extended permit tcp any object obj-10.254.254.5 eq www
access-list inbound extended permit tcp any object obj-10.254.254.5 eq 3389
object network obj-10.254.254.5
host 10.254.254.5
object network obj-10.254.254.5-01
host 10.254.254.5
object network obj-10.254.254.5-02
host 10.254.254.5
object network obj-10.254.254.5
nat (inside,outside) static interface service tcp www www

OLD – No NAT (seen mainly – but not always – on VPN traffic)

nat (inside) 0 access-list EXEMPT
access-list EXEMPT extended permit ip 10.254.254.0 255.255.255.0 172.16.254.0 255.255.255.0

NEW – No NAT

object network obj-10.254.254.0
subnet 10.254.254.0 255.255.255.0
object network obj-172.16.254.0
subnet 172.16.254.0 255.255.255.0
nat (inside,any) source static obj-10.254.254.0 obj-10.254.254.0 destination static obj-172.16.254.0 obj-172.16.254.0

Access Lists

For as long as I can remember when you allowed access to an IP address on a PIX/ASA you allowed access to its translated IP address, NOW YOU DO NOT, you allow access to its “Pre-translation address”

OLD Access List and Static NAT

access-list inbound extended permit ip any host 123.123.123.123 eq www
access-group inbound in interface outside
static (inside,outside) 123.123.123.123 10.254.254.5 netmask 255.255.255.255

NEW Access List and Static NAT

access-list inbound extended permit ip any host 10.254.254.5
access-group inbound in interface outside
object network obj-10.254.254.5
host 10.254.254.5
nat (inside,outside) static 123.123.123.123