Network Address Translation

Network Address Translation (NAT)

Network Address Translation enables a local area network to use one set of IP addresses for internal traffic and a second set of IP addresses for external traffic. This feature is used by the home portal so an end user can have an internal computer network in their home. This allows all the computers connected to it to use just one routable IP address to access the Internet. Network Address Translation is also known as network masquerading or IP-masquerading. This is a technique where the source and/or destination addresses of IP packets are rewritten as they pass through a router, firewall, or computer. It is most commonly used to enable multiple hosts on a private network to access the Internet using a single public IP address.

NAT is needed because the Internet has grown so much since it first came out. Originally, they thought that 232 addresses would be more than enough to support everyone. However, with over 350 million users, nearly 100 million hosts and the growth rate almost doubling every year, the number of available IP addresses is simply not enough. Network Address Translation allows a device to act as an agent between the public network and private network. This means that only a single, unique IP address is required to represent an entire group of computers.

Network Address Translation works in various different ways. NAT can map an unregistered IP address to a registered IP address one to another. It is also able to map an unregistered IP address to a registered IP address from a group of registered IP addresses. Port Address Translation (or PAT) is a single address NAT that maps multiple unregistered IP addresses to a single registered IP address by using different ports. The NAT router can translate the internal addresses to registered unique addresses as well as translate the external registered addresses to addresses that are unique to the private network. This is completed through static NAT and implementing dynamic NAT.