ELI5. what’s the difference between open NAT and double NAT?


ELI5. what’s the difference between open NAT and double NAT?

In: Technology

Open NAT is a concept that allows your computer or gaming console to connect to other computers or consoles using your public IP address with most ports open by default. Double NAT occurs when you have a router behind another router. Double NAT can make p2p connections difficult on devices behind the second router because the second network hides your public IP address. Double NAT should be avoided if possible by disabling NAT on the second router.

Keep in mind those two terms are specifically used on Xbox consoles, they aren’t general networking terms.

NAT is your home router’s way of translating your internal IP address (which isn’t recognised on the internet), into your external IP address (which is used by all your devices sharing the internet connection), and vice versa. NAT only works when your devices initiate the internet connection; the router knows this and can ensure the response that comes back is sent to the correct device.

If your router receives data that you didn’t ask for, it doesn’t know which device to send it do, so ignores it. That’s a problem for some games where you need to establish a direct connection between players (Peer-to-Peer, or P2P). If both players are behind a NAT, neither can establish the connection to the other.

The terms Open NAT and Double NAT are the Xbox’s way of determining the state of your home network.

Open NAT means your console has is ready to receive connections from the internet. That could be because you have no router (plugged directly into the modem), NAT is not being used, or your router is configured in such a way as to allow incoming connections to your console. Open NAT is good.

Double NAT means your console is behind two (or possibly more) routers with NAT enabled. With a single NAT, there are some tricks developers can use to try to work around it, but Double NAT makes that a lot harder to do. Double NAT is bad.