NAT INSIDE

NAT Inside basically means that any traffic on the inside interface as specified on the interface itself will be natted to an outside address Example of the inside interface

interface Ethernet0 description Ethernet0 ip address 192.168.240.1 255.255.255.0 ip nat inside end

Of course you need an IP NAT OUTSIDE for the interface on the outside, for example a Dialer interface in an ADSL config

In the above example The IP NAT INSIDE takes the IP address of an ethernet interface on a remote PC for example, and gives it a random port number before going to the outside address on the real IP address This allows for multiple computers in a network to share the one public IP assigned by the ISP and the external site for example knows which computer on the inside requested the information from the nat translation table that is built on the router

Hope that helps