Hi, what i'm trying to do is explained as follows:
I need to retrieve some JSON data from the Arduino (192.168.1.101) making an HTTP request to 80.X.X.X or to the associated DDNS.
First, i have a VPS linux Ubuntu server publicly exposed on the internet with the ip of 80.X.X.X on which i have installed OpenVPN Server.
The Arduino is connected to a 4g LTE Router, but since i was unable to configure a site-to-site vpn with ipsec, i connected a Raspberry Pi with an OpenVPN Client that connects to the VPS.
Now to retrive these data from the Arduino i need to forward all the HTTP requests made on port 8080 on the VPS to the Arduino (port 80) by: VPS eth0 -> tun0, then on the Rasp: tun0 -> 192.168.1.101
I've enabled forwarding in both linux systems, but the problem is that i need some help configuring iptables rules, i would greatly appreciate any help :)
Edit: To make some debugging i connected my home pc to the OpenVPN Server getting the host 10.8.0.3, then i downloaded Xampp to run a Web server and using these policies on the VPS i succesfully made an HTTP request for the sample xampp dashboard
-A PREROUTING -i eth0 -p tcp -m tcp --dport 8080 -j DNAT --to-destination 10.8.0.3 -A POSTROUTING -s 10.0.0.0/8 -o eth0 -j MASQUERADE
Now i dont know how to forward all the http requests to 192.168.1.101 on the Raspberry's LAN and then send back the response :( This is what I have tried so far
-A PREROUTING -i tun0 -p tcp --dport 8080 -j DNAT --to-destination 192.168.1.101:80 -A POSTROUTING -s 192.168.1.101 -o tun0 -j MASQUERADE