Network Address Translation (NAT) is a method by which network devices, such as the Synology RT2600ac router, translate private IP addresses used within a local network to a single public IP address when communicating with the internet. This allows multiple devices on the private network to share a single public IP address. For example, a home network might have several computers, smartphones, and smart TVs, all with private IP addresses like 192.168.1.x, but when these devices access the internet, their traffic appears to originate from the single public IP address assigned to the router by the Internet Service Provider (ISP).
The primary function is to conserve public IPv4 addresses, which are a limited resource. It also enhances security by hiding the internal network structure from the outside world. This added layer of protection makes it more difficult for malicious actors to directly target individual devices within the local network. Historically, it became prevalent due to the rapid expansion of the internet and the slower adoption of IPv6, which provides a vastly larger address space.
