|A1:||Cisco PIX Firewalls need to NAT any nonregistered IP address space. In particular, the Class A 10.0.0.0/8 is not routable in the Internet, so you must use NAT to permit access, or you could re-address your entire network, which clearly is not an exercise you will do often.
The following command will NAT all inside addresses:
nat (inside) 1 0.0.0.0 0.0.0.0
Before you can access the Internet, you must also tell the PIX (remember the PIX is not as intelligent as a router; RIP can be configured by the network administrator), and you must route IP data with the command shown here:
route outside 0.0.0.0 0.0.0.0 <default-gateway>
This command installs a default route where IP datagrams will be sent, typically, the perimeter ...