Why my external IP doesn't change when I am connected to a VPN?

Question

I am not so into networking and I have the following doubt related VPN connection.

Going to: https://whatismyipaddress.com/

I obtain that my IP address is 151.44.157.246

Ok then I connect to my VPN, it works fine (infact now I can reach some machines that require this kind of connection).

I go again on the same IP address checker: https://whatismyipaddress.com/

I expected to obtain a new IP address (the one provided by my VPN) but I am obtaining the same 151.44.157.246 IP address.

How is it possible? What am I missing? the strange thing is that if I am not conntected to this VPN I can't access in SSH to this cloud machine while if I am connected to this VPN I can do it.

What is wrong in my reasoning? From what I know using a VPN I go out on Internet with a different IP but probably I am missing something

Answer 1

VPNs work through a technique called tunnelling.

Here's how it works:

1. You launch the VPN

2. VPN software makes a connection to the VPN server.

3. Software installs a virtual network adapter with a VPN driver, and optionally configures your system so that all traffic goes through it, or just traffic going to certain subnets.

4. The VPN driver takes traffic going to it and instead of sending it to another computer on your network or your router, wraps it up in a VPN protocol, optionally encrypting it, and then sends it to the VPN server.

5. The traffic the VPN driver "wraps" still has to go out of your computer's physical NIC and through your router and ISP's network, since it's sent to the VPN server.

6. VPN server receives the wrapped traffic, decrypts and unwraps it, and sends it to the destination it was meant to go.

Your external IP is absolutely needed to talk to the VPN server, so it doesn't go away. You have 2 public IPs - one provided by your ISP and one your VPN is showing to the rest of the world.