I registered a virtual private server with a dedicated public IP and set up my own private VPN on it. Out of curiosity, I tried to access Netflix over it and I got the famous "You seem to be using an unblocker or proxy" screen.
I have always thought that Netflix simply maintains a blacklist of public VPN providers. But in this case I'm using my own private IP. How is it possible that Netflix is able to detect my VPN? Isn't it kind of a point of a VPN that it should not be detectable?
Note that the server is set up in a country where Netflix is actually very limited. Therefore it seems unlikely that anybody would run a public VPN to provide access to Netflix here and got all IPs owned by this provider blacklisted as a result.
Is it possible that Netflix simply detects a running instance of a VPN server (OpenVPN in my case) on my IP? Can that be prevented? I moved it from the default port (1194) but that didn't help.
Best Answer
Okay, mystery solved. As someone suggested in the comments, I tried to access Netflix directly from my VPS (I had to setup VNC for that) and got blocked!
The positive thing is that Netflix is clearly not using any dark magic to reveal that you are hidden behind a VPN (because in this particular case, I was not and got blocked anyway).
The negative thing is that Netflix is apparently very aggressive when it comes to blocking IP addresses.
Until now, I was under the impression that Netflix blocks IP addresses based on the suspicious traffic going through those IPs. In the case of this particular VPS provider, I find it very unlikely. I seriously doubt that anybody has built a public VPN which was heavily used to access Netflix because the provider is located in a country where Netflix gets only around 10% of the US content. It would make no sense at all to tunnel to this country to watch Netflix.
My guess would be that Netflix uses some kind of smart algorithm to distinguish between IPs belonging to ISPs (those are good) and to VPS providers (those are bad as they are likely to be used for VPNs). My IP is registered to a company whose name actually contains the word "hosting" which means that the algorithm didn't have to be really smart in this case.
So to answer my original question, I'd say that even though nothing suggests that it is actually possible to detect a VPN, the source IP address can reveal enough information about itself to make it clear that this is no Jon Doe browsing from his home computer.