VPN and Proxy detection provide an invaluable service to many users, allowing them to protect their privacy, access content that would otherwise be blocked in their country, or perform web tasks more securely. But some use these tools for nefarious purposes, such as hacking, fraud, and identity theft. As a result, websites need to be able to detect and prevent users from connecting through a VPN or proxy.

Detecting VPN and Proxy Use: Methods and Tools Explained

The good news is that there are several ways to identify users connecting through a VPN or proxy. The most reliable method involves examining the connection’s network traffic and looking for a signature that matches with known VPN providers and proxies. This can be done using a number of methods, including comparing the device’s timezone with the timezone of the target server’s location, performing a ping test, or identifying connections that use tunneling protocols such as SSL/TLS, OpenVPN, SOCKS5, and Tor.

Other detection methods include cross-matching the user’s IP address with databases that list information about VPN and proxy services, or recognizing connections utilizing non-standard ports such as TCP 443, TCP 1194, or UDP 1701 that are commonly associated with VPN and proxy usage. These methods have their drawbacks, however, and some may cause erroneous results due to other factors unrelated to VPN or proxy usage (for example, network configuration and MTU values).