Generating any kind of traffic backwards from an Internet server in response to an incoming client (a port scan, or even a simple ping) is generally frowned upon. So either you'll not catch those you want, or you'll have a larger number of false positives. You might invent some tests, but those will have a very low correlation with the reality.

Unfortunately, there's is no proper technical way to get the information you want. I just want to entirely bar connections from VPNs or Proxies.Įdit: I've been thinking that I could potentially run a test to see if there is consistent discrepancies between ping to the VPN IP and the detectable latency of the client, but that sounds pretty unreliable.Įdit2: A proxy or VPN server would likely have many more ports open than a standard home connection so I could use the number of ports open to help gauge the likelihood of a connection coming from a VPN by running a port scan of the person connecting. Is there anyway to detect that a VPN or proxy connection is being used? If not, is there anyway that I can check the likelihood that a VPN or proxy is being used? Lastly, is there anything that I can query or prompt the user with to check if they are using a VPN or Proxy so that if anyone does get through, I can try and perform additional verification? I do not need any information from the user such as location, true IP, or anything like that. I would like to block all connections to my server that use a VPN or Proxy.

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