atlas-dedicated-server/Documentation/NAT reflection (hairpinning, loopback etc.).md

So you have a NAT reflection problem. What now?

You've been directed here by someone from our Discord's Support group. Your symptoms seem to indicate that you have a NAT reflection problem: your router is not forwarding requests from inside your LAN through your public-facing IP address.

This is normal. You see, it's potentially a security risk to allow this traffic - it often indicates you have malware installed, or your network is improperly configured. Many routers silently DROP this traffic.

The good news is - your server is probably perfectly reachable from the Internet. Yay!

Other people will be able to see and connect to it just fine.

The bad news is - you won't be. And to make it worse, nobody except the router manufacturer can tell you how to fix this on your particular device. Sorry.

What you have to do is make sure your router redirects requests from inside your LAN, returning back in via the WAN interface. Please consult your device's manual on how to set up NAT reflection (possibly also called "NAT loopback", "NAT hairpinning" etc.).

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If you happen to be running iptables however, here's a line to get you started:

iptables -t nat -A PREROUTING -i ! YOUR-WAN-INTERFACE -s LAN-NETWORK -d PUBLIC-IP -p tcp --dport PORT -j DNAT --to-destination LAN-SERVER-ADDRES Explanation:

• -i ! YOUR-WAN-INTERFACE is there to make sure you don't accidentally include traffic from the Internet - the traffic we want to modify is handled within the router itself (and also, it never hurts to prevent spoofing)
• -s LAN-NETWORK defines your LAN's network pool - for example -s 10.0.0.0/8 - this is to make sure you're only affecting traffic originating from your local LAN
• -d PUBLIC-IP line tells it to look for traffic that has a destination of your public IP address
• --dport PORT is the port you wish to affect, and
• --to-destination LAN-SERVER-ADDRESS tells it to redirect all traffic that matches to your ATLAS server's LAN IP

So, to summarize, "All traffic that comes in NOT via WAN but comes from LAN, and is destined for the PUBLIC IP and PORT, redirect to internal LAN IP of the server".

I hope this helps some.