Network Address Translation (NAT) is a service that enables private IP networks to access the Internet and the cloud. It works by having a firewall act as an intermediary for traffic entering and leaving the protected network. Incoming traffic is directed to a public IP address, which translates to an internal IP address of the firewall before the traffic is sent to its destination. NAT offers a variety of uses and benefits, from home networks to extended office and business networks. A device on the network only needs a public IP address; the router assigns one based on its own configuration settings.
When requesting a file transfer, the host making the request identifies the corresponding data connection using its network layer and transport layer addresses. It may be necessary to examine and classify the type of mapping used, for example, when you want to configure a direct communication path between two clients, both located behind separate NAT gateways. NAT also provides additional security by allowing only one IP address of an entire network to be revealed to the outside world. It translates private IP addresses from an internal network to a public IP address before sending packets to an external network. NAT only translates the IP addresses and ports of your internal hosts, hiding the true endpoint of an internal host on a private network. A router is a device for the network layer, but as a NAT device it is necessary to manipulate the transport layer in the form of port numbers.
This type of NAT is suitable for use in large business networks, where many private network devices must access the Internet frequently as required.