Network address translation (NAT)

Network address translation (NAT) is a process used in computer networking to modify network address information in the IP header of packets while they are in transit across a network. This allows multiple devices within a local network to share a single public IP address when communicating with devices outside the local network, such as on the internet. NAT serves as a crucial tool for conserving public IP addresses, as it allows a single public IP address to be shared among multiple devices within a private network.

NAT operates by mapping private IP addresses of devices within the local network to a single public IP address. When a device within the local network sends a packet to a device outside the network, NAT modifies the source IP address in the packet's header to the public IP address. When the response packet is received from the external device, NAT then translates the destination IP address back to the private IP address of the originating device.

There are several types of NAT, including static NAT, dynamic NAT, and port address translation (PAT). Static NAT involves manually configuring a one-to-one mapping between private and public IP addresses, while dynamic NAT dynamically assigns public IP addresses from a pool of available addresses. PAT, also known as overload NAT, maps multiple private IP addresses to a single public IP address by using different port numbers to distinguish between the devices.