How to detect a proxy or VPN?

@hanna 

To detect a proxy or VPN, you can follow these methods:

1. Check IP address: Use online tools or websites like WhatIsMyIPAddress.com or IP2Location.com to verify the IP address of the user. If the IP address belongs to a known proxy or VPN server, it indicates the usage of such services.
2. Analyze network traffic: Analyzing the network traffic and monitoring the various packets being sent can help identify patterns or anomalies associated with proxy or VPN connections.
3. Examine the Time to Live (TTL) value: The TTL value indicates the number of hops a packet must travel before it reaches its destination. If the TTL value is unusually high, it suggests the usage of a proxy or VPN.
4. Use blacklists: Utilize IP blacklist databases that maintain a list of known proxy or VPN server IP addresses. By cross-checking the user's IP against these blacklists, you can determine if they are utilizing such services.
5. Analyze headers: Check the HTTP headers of the user's web request. Proxy or VPN servers often add additional headers like "X-Forwarded-For" or "Via" that can indicate the usage of a proxy or VPN.
6. Monitor behavior: Pay attention to user behavior patterns, such as multiple accounts originating from the same IP address, frequent IP changes, or suspiciously high connection requests. Such patterns may indicate the use of proxy or VPN connections.
7. Use CAPTCHA or JavaScript challenges: Implement CAPTCHA or JavaScript-based challenges that require users to solve puzzles or execute specific actions to access certain resources. This can help determine if the user is behind a proxy or VPN.

It's important to note that detecting proxies or VPNs is not foolproof, and determined individuals may still find ways to bypass detection methods.