What is the use of NAT in networking

How does NAT help a network service for data backup and other support. I had found both small and large scale organization configure NAT on the network. It is essential to configure the same properly. But I am not able to understand the exact working of this behind the scene. The data is same which is transformed from the cable to the storage media and thus similar to file sharing stuff. But does NAT really provides some kind of extra support. And if yes then how that can be explained.

The NAT is designed initially with the purpose of solving the problem of scalability of IP addresses and exhaustion for the allocation of new IP numbers, another advantage of NAT is to hide the scheme Address outside a private network providing an important service for a security solution. The strategy used by the application of this technology is based on the topological distribution of the future allocation of IP addresses for each network address space to the different domains of data traffic routing (private networks).

Here is the way how NAT works. When a packet is sent outside the network, the source IP address is translated to a globally unique address to avoid possible conflicts with other address spaces assigned to other private networks and hide the addressing scheme of the local network. For this, the NAT function is implemented at each exit point between the private network and public network connection. Each NAT has a table of IP address pairs which consist of local addresses and globally unique addresses assigned to perform the mapping.

Address Translation allows a single device that interconnects the private network to external network, such as a router or a firewall, acting as an agent between the Internet and local network. NAT can be installed without major changes to these devices, making it a good option with significant benefits. NAT is transparent to internal and external systems and operate in the network layer without adding much additional computation time communications.

OpenBSD systems configured to NAT will have at least two network adapters, one for Internet and one for the internal network. NAT will translate the requirements from the internal network, so it appears that all OpenBSD system from which NAT is configured. When a client on the internal network contacts a machine on the Internet, send IP packets destined for that machine. These packages contain all the addressing information necessary for them to be taken to their destination.

The concept of static NAT is to match a public IP address with an IP address internal private network. A router (or, more precisely, the gateway ) matches a private IP address (eg 192.168.0.1) with a routable public IP address on the internet and in a sense, performs the translation by modifying the address in the IP packet. The static address translation to connect the internal network machines to the Internet in a transparent manner, but does not solve the address shortage problem because it takes n-routable IP addresses to connect n machines internal network.