Published on Mar 7, 2023
Ghadeer Al-Mashhadi
Read time: 4m
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5 Ways to Detect VPN & Proxy to Prevent Fraud

Businesses need to detect and prevent the use of VPNs and proxies to minimize the risk of fraud. There are several methods to detect VPN and proxy usage, including IP-based detection, comparing browser timezone with IP timezone, DNS-based detection, and port-based detection.


In today's digital world, VPNs and proxies are widely used to protect online privacy and security. However, these tools can also be used for fraudulent purposes, such as identity theft, hacking, and fraudulent purchases. Therefore, it is essential for businesses to detect and prevent the use of VPNs and proxies to minimize the risk of fraud. In this article, we will discuss four effective ways to detect VPN and proxy usage to prevent fraud.

Online payment fraud losses to exceed $343 billion globally over the next 5 years – Juniper Research Study.

Understanding VPN/Proxy Detection

VPN/Proxy detection involves the act of determining whether a user is accessing a website or online service by utilizing a VPN or proxy server. By employing VPNs and proxy servers, users gain the ability to hide their IP address and geographical location, making it difficult for websites or online services to accurately identify their true identity and location. While it is true that some users legitimately use VPNs or proxies to access restricted content or protect their online privacy, there are also individuals who exploit these tools for malicious purposes, including engaging in fraudulent activities or hacking.

Methods for Detecting VPN/Proxy Usage

Several methods can be employed to detect VPNs and proxies:

1. IP-based Detection

The first method to detect VPN and proxy usage is through IP-based detection. This approach involves comparing the user's IP address with a list of known VPN and proxy IP addresses. However, it is important to note that this method can be challenging due to the constant growth of VPN networks. To stay effective, it is necessary to continuously update the database of blacklisted IPs and remain up-to-date with the latest VPN and proxy services. If the user's IP address matches one on the blacklist, it suggests that they are likely using a VPN or proxy. It is advisable to combine IP-based detection with other techniques for more accurate identification of VPN and proxy usage.

2. Browser Timezone vs. IP Timezone Comparison

An alternative method for detecting VPN or proxy usage involves comparing the timezone reported by the user's web browser with the timezone associated with their IP address. This technique capitalizes on the potential inconsistency between the user's actual location and the IP address used to access the web through VPNs or proxy servers.

Web browsers typically provide information about the timezone configured on a user's device. Meanwhile, the IP address associated with the user's connection can be geographically located, yielding the expected timezone for that specific region. By contrasting these two data points, it becomes possible to identify disparities that may indicate the presence of a VPN or proxy.

For example, if a user's browser indicates a timezone corresponding to a particular country, but the geolocation of the IP address suggests a different country with a conflicting timezone, it raises suspicion. Such discrepancies may suggest an attempt to mask the user's true location by leveraging VPNs or proxy services.

It's important to acknowledge the limitations of this method. Users can manually adjust their device's timezone settings or use browser extensions to manipulate the reported timezone, which can lead to false assumptions. Additionally, false positives may arise when legitimate users travel or have valid reasons for employing a timezone different from their IP geolocation.

PRO-TIP: To enhance accuracy and minimize false positives, it is recommended to combine the Browser Timezone vs. IP Timezone Comparison with other detection techniques and contextual factors.

3. DNS-based Detection

To detect the usage of VPNs or proxy servers, websites have the capability to examine a user's DNS queries. Certain VPN and proxy services utilize unique DNS servers that can be identified and flagged. Implementing DNS-based detection involves the maintenance of an regularly updated database that includes blacklisted DNS servers. When a user's DNS queries correspond to an entry on the blacklist, it serves as an indication of VPN or proxy usage. This method enables websites to effectively identify and mitigate the presence of VPN or proxy connections.

4. Port-based Detection

Websites have the option to inspect the connection made by a user and determine whether it is utilizing a non-standard port typically associated with VPN and proxy services. VPN and proxy providers often employ non-standard ports, such as TCP 80, TCP 443, TCP 1194, TCP 1723, and UDP 1701, in an attempt to avoid detection.

It is important to note that relying solely on port-based detection may not always yield accurate results, as legitimate users may also utilize non-standard ports for various reasons.

5. Third-Party Services

Websites can leverage third-party services like Greip for VPN and proxy detection. Greip employs machine learning algorithms to analyze network traffic and identify VPN and proxy connections. It can also recognize connections utilizing VPN or proxy protocols, such as OpenVPN, SOCKS5, etc. Integration with Greip's REST API enables websites to seamlessly incorporate VPN and proxy detection into their systems.

For further information, please visit Greip's home page or refer to the documentation.


In conclusion, the usage of VPNs and proxies poses significant risks to businesses, necessitating effective detection and prevention measures to mitigate fraud. By implementing the strategies outlined above, businesses can successfully identify VPN and proxy usage, thereby safeguarding against fraudulent activities. It is crucial for businesses to stay proactive and remain updated with evolving VPN and proxy technologies to maintain efficient fraud prevention protocols.

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