Network Address Translation

NAT or Network Address Translation is a technique of transceiving the IP traffic through the router and it involves the rewriting of the source and the destination IP addresses and the UDP/TCP port numbers of IP packets.  It is a method of connecting multiple computers with the internet through a single IP addresses. With the huge growth of the internet there is a big demand of the IP addresses and here the NAT comes into play.  

  NAT was developed by the Cisco and it is being used for the internet connection sharing, load balancing and filtering the incoming and outgoing traffic.  It enables the single communication device to act as intermediary between the internet and the local computer network and due to this a single IP addresses can be used with and whole group of computers.

NAT enabled device such as a router or computer sits between the internet and the local network.  The key advantages of the Network Address Translation have been described below.

• It is used for reusing the IP addresses.
• It provides the internet access to the remote clients.
• It provides the firewall functionalities to the NAT enabled routers and also hides the internal IP addresses.
• It allows the organizations to combine multiple ISDN connections into a single connection.
• It enables the organization to use more internal IP addresses.
• It provides the PPPoE broadband internet access.

It bundles the NAT, DHCP and DNS for smaller computer networks.

There are the four types of NAT.

• Full Cone.
• Restricted Cone.
• Port Restricted Cone.
• Symmetric.

The most common reasons to implement the NAT in your computer network is the security and the administration.  As the amount of information and resources is increasing at a exponential rate, it has now become the requirement of every home and business user to connect to the internet.
NAT multiplex your whole computer network traffic on the internet as it is coming from a single computer and a single IP address.  Network Address Translation works in the following different forms.
Static NAT:   It maps the unregistered IP address to the registered IP address on the one to one basis and it is useful when a device needs to be accessible from the outer network.
Dynamic NAT:  It maps the unregistered IP address to the registered IP address through the group of the registered IP address.
Overloading:  It is a form of the dynamic NAT that maps multiple unregistered IP addresses to the single registered IP address by using the different ports.