Network masquerading, commonly known as Network Address Translation (NAT), is a technique used in computer networks to modify the network addresses in the headers of data packets while they are in transit, usually for the purpose of remapping an IP address from one address space to another.

This is done for a variety of reasons, such as to provide additional security by hiding internal IP addresses, or to allow multiple devices to share a single public IP address.

Basic operation

Network masquerading is typically performed on a network device, such as a router or firewall, that acts as an intermediary between the internal (private) network and the external (public) network, such as the Internet.

When a device within a private network wants to access the Internet, the router converts the private IP address of the sending device to a public IP address assigned to the router. This process is known as egress NAT or SNAT (Source NAT).

Main Purposes

1. Conservation of IP Addresses: Allows multiple devices on a private network to share a single public IP address. This is crucial due to the shortage of available IPv4 addresses.
2. Security: By hiding the internal IP addresses of a network, NAT provides a level of security, since the real IP addresses of devices on the internal network are not directly exposed to the Internet.
3. Simplicity and Convenience: Makes network management easier by not requiring each device to have a unique public IP address. This is especially useful for home networks and small businesses.

NAT types

• Static NAT: Assigns a public IP address to a specific private IP address permanently. It is useful for services accessible from the Internet, such as web or mail servers.
• Dynamic NAT: Maps any available public IP address from an address pool to a private IP address whenever necessary. This is common for general Internet access for internal users.
• PAT (Port Address Translation) o Overloaded NAT: A variant of dynamic NAT that allows multiple devices to share a single public IP address by differentiating connections by port number. It is the type of NAT most commonly used in home and small office networks.

Considerations

While NAT provides significant benefits in terms of security and address management, it can also introduce complications in certain scenarios, such as the need for additional configurations to allow specific incoming connections (port forwarding), and potential problems with applications sensitive to tampering. addresses or ports.

With the adoption of IPv6 and its vast address space, some of the problems that NAT seeks to solve could become less relevant, although the global transition to IPv6 is still in process.