I currently use a VPN supplier that does not allow for opening ports. They argue that I lose the whole point of a VPN and the anonymity by doing this. I can't see how and they don't seem to be able to explain how this would work for me.

Shouldn't I still be protected behind the NAT of the VPN?

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    In your understanding, how does NAT protect you? – schroeder Feb 17 at 19:52
  • @schroeder I will connect to the VPN with in IP, then I will get a new external IP. So opening a port in the NAT linking the external IP to my private IP will still hide my IP. Only the VPN provider will still know my internal IP? – Jesper.Lindberg Feb 18 at 11:08
  • Yes, you are correct that NAT protects your IP on your side of the NAT. Your internal IP is protected but that's not the only thing that can unmask you. My answer below does not describe a perfect anonymity situation, but it makes it more difficult. – schroeder Feb 18 at 11:14

Opening a unique port just for you? Yes, you lose anonymity, even with NAT, because now that traffic on that unique port unique identifies your traffic.

One of the benefits of a VPN is that your traffic gets co-mingled with so much other traffic that it is difficult to uniquely identify users. Your proposal eliminates this benefit.


You have to consider your threat model.

If you use VPN for anonymity, then opening dedicated port means you lose anonymity because the way VPN anonymity works is essentially by mixing your traffic. Anything that can be used to uniquely identify your traffic (e.g. port number) works just as well to help deanonymize you.

If you use VPN merely to hide your real IP, then the VPN will still mask your real IP if they open a dedicated port for you.

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