Need to understand OpenVPN works

[Guest]

Hello community,

I'm new to AirVPN, and OpenVPN by the way. Everything's working fine so far, but Id' like to understand how it works, just to make sure I don't miss any backdoor.

Let's say I'm connected at home on my WLAN with IP 192.168.1.10.

I've generated a UDP file with AirVPN and choose a server in US. Once connected with OpenVPN, I see that my IP is 10.0.0.1, and on Internet I'm seen as 96.0.0.1 (example IPs). I understand that 10.0.0.1 is my tunnel address, while 96.0.0.1 is my public address once I'm leaveing the tunnel on VPN server. Am I right ?

There is one thing I don't understand. I thought everything would go inside the tunnel. Still I'm able to reach local devices: I can ping my router, can reach my NAS.... Why's that ?

Thanks in advance.

[OpenSourcerer 1359]

19 hours ago, Arnaud Ciron said:

Am I right ?

Yes.
 

19 hours ago, Arnaud Ciron said:

Still I'm able to reach local devices: I can ping my router, can reach my NAS.... Why's that ?

Well, to have a connection to AirVPN you will need to have a connection to your local network of course. And to have this connection, your OS configures your network interface with its values received by DHCP, i.e. IP address and network mask for instance and adds a route to it to the kernel routing table (what you see when you run route print (Windows) or ip r (Linux) for example).

A configuration parameter pushed by AirVPN servers is redirect-gateway. It's a functionality to automatically add routes to the table to route all traffic through this VPN connection, also by means of changing the default route. This default route is only taken if there is no explicit route for your destination, but because you actually do have this explicit route added, packets to your local net will be routed there, therefore you can access your local devices.

[Guest]

6 minutes ago, giganerd said:

Yes.
 
Well, to have a connection to AirVPN you will need to have a connection to your local network of course. And to have this connection, your OS configures your network interface with its values received by DHCP, i.e. IP address and network mask for instance and adds a route to it to the kernel routing table (what you see when you run route print (Windows) or ip r (Linux) for example).

A configuration parameter pushed by AirVPN servers is redirect-gateway. It's a functionality to automatically add routes to the table to route all traffic through this VPN connection, also by means of changing the default route. This default route is only taken if there is no explicit route for your destination, but because you actually do have this explicit route added, packets to your local net will be routed there, therefore you can access your local devices.

Thanks for explanations, very clear.