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Network Address Translation (NAT) in Computer Network
Computer Network | Network Address Translation (NAT): In this tutorial, we will learn about the Network Address Translation (NAT) and the Address Translation.
By Radib Kar Last updated : May 04, 2023
Network Address Translation (NAT)
At the time of classful addressing, the number of household users and small businesses that want to use the Internet kept increasing. In the beginning, a user was connected to the Internet with a dial-up line, for a specific period of time. But the situation turned different. Household users and small businesses can be connected by a cable modem. In addition, many are not happy with one address as many have created small networks with several hosts and need an IP address for each host. With the shortage of addresses, this is a serious problem.
There is a quick solution to this problem is called NAT (Network Address Translation). NAT enables a user to have a large set of addresses internally and one address or a small set of addresses, externally. The traffic inside can use the large set, however, the traffic outside is only the small set or one address.
To separate the addresses used inside the home or business (internal ones), the Internet authorities have reserved three sets of addresses as private addresses, shown below,
10. 0.0.0 to 10.255.255.255
172. 16.0.0 to 172. 31.255.255
192.168.0.0 to 192.168.255.255
Any organization can use an address that may out of this set without taking permission from the Internet authorities. Globally known that these reserved addresses are for private networks.
These addresses are unique in an organization, but they are not unique globally. No router will forward a packet directly to the destination that has one of these addresses.
Address Translation
All the outgoing packets go through the NAT (Network Address Translation) router that replaces the source address in the packet with the global NAT address. All incoming packets also pass through the Network Address Translation (NAT) router, which replaces the destination address in the packet.