INFO: What is NAT
In your house or business, computers communicate with other computers, servers, printers, and other networked devices. Routers pass this information between these devices internally, usually based on some type of private IP Address convention. When one of these devices needs to communicate outside the network, like accessing the Internet, it requires a public IP address. This is the point where NAT takes over and eliminates the need for that device to have a public IP address.
In a nutshell, here's what happens:
These steps occur for every device on the network. Now, when a number of computers or devices make requests outside the internal network, the router passes them all on but uses just one external IP address.
1. A computer makes a request for information located outside of the private network.
2. The request is sent to the router.
3. The router makes a note of the address the request came from and passes it along using its own public address.
4. When the request receives a reply, the router passes the reply back to the computer that made the original request.
This allows for just one single IP address to represent multiple devices.
NAT can also be used to enhance network security by allowing selective access to locations outside the network. Computers that may need specific access to the locations outside the network can be assigned unique IP addresses and the router can then keep track of the packets an addresses that pass through allowing only the appropriate items.