- Jan 8, 2011
Blog: VPN Detection: Overview of Methods and Techniques
- Overview of VPN detection methods
- Database validation
- Time zone mismatch
- Transmission Control Protocol (TCP) /IP Detection
- OS mismatch
- Maximum Transmission Unit (MTU)
- Other VPN detection techniques
- Port Scanning
- WebRTC IP address leakage
- DNS IP address leakage
- Latency Test
- HTTP/Proxy Headers
- Detecting VPN Browser Extensions
TorTor is also worth mentioning. Tor, short for The Onion Router, is a well-known anonymity network. Detection of the Tor network involves recognizing the IP addresses associated with Tor nodes and output relays. Tor user traffic passes through a series of servers, and the IP address of the exit relay becomes visible when the user goes out to the open Internet. Identification of these IP addresses can indicate the use of the Tor network.
Tor users are well aware of the detection method and often employ countermeasures to protect their anonymity. They may configure Tor bridges, use obfuscation techniques, or use VPNs, creating additional detection challenges. These countermeasures illustrate the constant cat-and-mouse game between privacy-conscious users and those trying to identify their browsing practices.
ConclusionVPN usage has drastically increased over the last few years, with a third of all internet users having used a VPN. While there are many added security and user experience benefits for an internet user to utilize a VPN provider, there's the darker side of fraudulent activities conducted through VPN usage, including malware distribution, click fraud, and identity theft.
We showed several VPN detection methods, which range from simple timezone mismatch that correlates with anonymizing services usage to more advanced techniques that inspect the packet structure to search for known deviations from the standard and are therefore able to detect underlying VPN protocols.