Appendix | Network Connection |
What’s a Network Address Translator?
A NAT is a set of services on the router that allow you to operate a local network of devices, each with its own locally unique IP address, while communicating to the Internet through a router which presents a single, globally unique IP address to the outside world. Most small business and home office (SOHO) routers provide NAT services.
The NAT ensures that outgoing packets have a globally valid IP address, and that incoming packets go to the right device by translating between the internal IP address and the external IP address, owned by the router. This also adds an extra level of security by effectively masking the internal network behind a single external IP address.
A simplified explanation of how this translation takes place is that when an internal device sends an outgoing packet to the router, the NAT service either notes the internal IP address or the port number of the device, and attaches an identifier to the external IP address of the outgoing packet, substituting the router’s globally unique IP address for the device’s internal IP address. When the answering packet comes back, the NAT notes the indentifier,
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