Is there a realistic purpose behind "Tor over VPN" service provided by ProtonVPN

As you might know, ProtonVPN offers an exclusive feature that makes use of the Tor network by routing users' VPN traffic to tor relays after it passes through the real VPN server. This way, basically users' public IP address would be from the tor exit relay instead of the VPN server s/he is connected to.

However, I do not see the obvious advantages of this particular add-on feature. So I sent an email to ProtonVPN's security team hoping to get some explanations, only not to get anything back from them. So I am now posting my original email body here, hoping some of the community members may be able to help answer my question. The email body is as attached below.

Hi    I just read the article on protonvpn's blog that explains the feature of "Tor over VPN". I have a few questions whose answers may clarity my confusion.    > At ProtonVPN, we implement Tor over VPN, meaning your Internet traffic is encrypted all the way through the Tor network, and your true IP address is never revealed to your ISP or to any Tor nodes.[1]    I don't understand why your true IP address is never revealed to your ISP when using "Tor over VPN", since ISP(s) manage how public IP addresses are assigned within its own network, and therefore can always analyze the data packets from that particular IP address to its destination, at the location of their routers, right? In that way, the advantage of using such a feature is not justified.    > The VPN will encrypt some Internet traffic that Tor does not support, like ICMP traffic. It also prevents your ISP from knowing you are connecting to Tor.    I certainly agree on the idea in the quote underlined. But my question is in which case does your ISP care about the fact of whether your are connected to a tor network? And what difference does it make if they can also always know that your are connected to a protonVPN server?    I am looking forward to your reply.    [1] https://protonvpn.com/blog/tor-vpn/      Best Regards  S. X. Liang  www.theanonymity.de    [[[ To any NSA and FBI agents reading my email: please consider    ]]]  [[[ whether defending the US Constitution against all enemies,     ]]]  [[[ foreign or domestic, requires you to follow Snowden's example. ]]]  

The next piece, as a follow-up to the previous email.

As a follow-up to the last email, I have one more question regarding the feature of "Tor over VPN".    > However, there are also disadvantages of using Tor over VPN. While ProtonVPN supports both TCP and UDP traffic, Tor only supports TCP.    What exactly does it mean by "Tor only supports TCP"? Is true that tor only accepts incoming connection traffic in TCP, or only TCP data traffic is routed through the tor network? If the later, what happens if I am sending UDP traffic connected to ProtonVPN server with "tor over VPN" feature enabled? Are these UDP data packets dropped, or sent out via the protonvpn server's network?  

I am also hoping to be corrected if my understanding of computer network is wrong or inaccurate. Your answers will be very much appreciated.

https://stackoverflow.com/questions/65878470/is-there-a-realistic-purpose-behind-tor-over-vpn-service-provided-by-protonvpn January 25, 2021 at 11:07AM