Things your ISP Sees Even When You Use a VPN

A Virtual Private Network (VPN) is often used by internet users to protect, secure and keep their sensitive online information, online traffic and browsing activities, private from Internet Service Providers’ (ISP) tracking and storing data activities. This mentioned practice has been common since the creation and implementation of data retention laws in some countries. Though this is the case, a VPN could circumvent and bypass these laws by encrypting your data and preventing your ISP from tracking and monitoring your online activities. Even with that said, unfortunately, there are some things that your ISP could still see even when you are using a VPN. To find out what are those, read further and learn more.

Could Internet Service Provider (ISP) see that you are using a VPN?

As mentioned earlier, a VPN has the ability to secure, protect and keep your personal data private from your ISP, third parties and governments. It has the ability to encrypt your online traffic from end to end. This means that no one else will be able to read your sensitive online information nor know your online activities. Though this is the case, you will have to take note that in the case when internet traffic made via VPN travels through your ISP, it would be easy for your ISP to know that you are using a VPN. Aside from that, your ISP could also know what time and the amount of data you are using. Though this data is general there are more information and other things that your ISP could know and tell.

How ISP detects VPN connection?

There are different methods and ways that your ISP and your government could use to know and determine if you are using a VPN. Here are the three major/main methods that they usually use:

  1. VPN server IP detection
  2. Deep Packet Inspection
  3. Port number detection

VPN server IP detection

When you connect to a VPN server, your ISP will be able to tell your real IP and where you are trying to connect. Though the IP address’ destination does not say much, it would be easy for your ISP to tell who is the owner of the IP address through little and simple research. It could even check a particular IP or range of IP addresses if it belongs to a certain/specific VPN service provider. There are even some ISPs that could blacklist VPN server IP addresses.

Aside from VPN server’s IP address could be identified but, unfortunately, yours as well. Hence, with that said, it is easy now for your ISP to track your location and information. In other words, your ISP could identify you as a VPN user.

Deep Packet Inspection

A deep packet inspection goes beyond detecting one’s IP address and port number. This means it inspects IP packet’s headers. A packet is sent via the internet in two main parts:

1. Packet Payload- a deeper portion of the packet. This comes with data sent which is usually encrypted by VPN services.

2. IP packer header- this contains your IP address, protocols used and port number.

Whenever you ISP uses deep packet inspection, it analyzes your IP header information and look inside the data it carries inside the packet. It uses methods that could find patterns that would resemble to a VPN traffic. Though this is the case, your ISP will not be able to tell what kind of data you have inside your packet payload. Hence, it will not be able to identify where you currently really are trying to connect to or what you are trying to download. The reason behind this is due to the encryption function/features your VPN has. To avoid being detected, you will have to use a VPN that has stealth and obfuscation technology since these types of VPNs use different ports and protocols which makes it more difficult to spot.

3. Port number detection

There are times that IP address is not enough to know if you are using a VPN. However, this is more possible through detecting the port you are connected to. When a VPN is initiated, your connection uses VPN protocols which sometimes is common which makes it easier for your ISP to identify if you are using a VPN or not.

Here are seven things that your ISP could see when you are using a VPN.

  1. If you are using a VPN
  2. VPN server IP address
  3. Your IP address
  4. The time you have connected to a VPN server
  5. VPN protocol used
  6. Encrypted data stream
  7. Amount data used

Do ISPs really care if you are using a VPN?

ISP is a business that has a goal to earn profit. This means it will have to comply with laws. However, each country has different laws especially when it comes to using VPNs. Hence, the answer to this depends on which country you are in. If you are in the western part of the world, VPNs are allowed. Hence ISPs really do not care if you are using one. However, if you are in a country where VPNs are not allowed. There are ways as you could see for ISPs to detect if you are using a VPN and will try to block your connection.

What could happen if a VPN connection is detected?

Without an obfuscation technique, it would be easy to detect if you are using a VPN and if this happens, your ISP could:

  1. Block your VPN. Yes, your ISP could block servers IP addresses by filtering out DPIs. This is rare in Europe and in the US but in countries like China, Iran, UAE, etc. VPNs are and will be blocked. Fines could be imposed as well if you get caught.
  2. Throttle your VPN. This will reduce your speed. Hence, you will have limited internet usage. Though this is a common practice, this could be solved through stealth VPN traffic and/or use a different port.


ISPs now have different advanced methods and techniques to know if you are using a VPN. It could also identify the time you have used a VPN, the data that has been transmitted and your IP address and your VPN’s. Though this is the case, the good news is, it could not tell what kind of data it is inside the VPN tunnel and where you connect to due to encryption features that a VPN usually have. Hence, even if your ISP could identify your VPN connection, it is still a great tool to keep your data and information private.

Renee Biana

VPN Pick brings you all the latest vpn news, reviews and discounts.

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