What Your ISP Still Knows About You, Even With a VPN
Although a VPN encrypts your traffic and hides much of your online activity from your ISP, it is often mistakenly believed that it makes you completely invisible. Even with an active VPN, your ISP can still see specific details that you might assume are hidden. Let’s explore what information they can access.
Your ISP can detect VPN use
VPN traffic carries an encrypted “signature” that distinguishes it, allowing ISPs to detect it if they wish. Since many VPNs rely on data center IP addresses, traffic routed through these addresses often indicates VPN use. Additionally, tunneling protocols like OpenVPN or WireGuard operate on specific ports, making them easier to distinguish from regular HTTPS traffic.
Regular browsing produces varied and inconsistent requests, while VPN connections typically send packets of uniform size and timing – another telltale sign. Some ISPs use Deep Packet Inspection (DPI) to analyze traffic metadata. Even if the content remains encrypted, the traffic pattern can still reveal that you are using a VPN.
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When you log in and out
Your VPN does not hide the start or end of your sessions. This is because your device must first connect through your ISP before it can reach the VPN server. Therefore, your ISP can always see the exact times you connect or disconnect, even if it can’t monitor what you do while you’re connected. From this information, your ISP can estimate the duration of each session.
Over time, if you follow the same routine for days or weeks, your ISP can track your typical online schedule and identify your VPN usage patterns. Knowing this, your ISP might choose to throttle your connection, thereby slowing down your Internet speed, and this slowdown might even affect you when you’re not actively using a VPN.
The sites you accessed
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DNS queries convert the name of a website (such as google.com) to its corresponding IP address. A VPN is supposed to route all your internet traffic through its encrypted tunnel, but if it’s misconfigured or lacks proper protection, these DNS queries can bypass it and go through your ISP’s servers. This is called a DNS leak.
Although DNS leaks are rare, they allow ISPs to see exactly which websites you visit. You may think your traffic is hidden, but in reality, your ISP could still be logging the sites you search for. To avoid this, you can use a trusted VPN that includes strong DNS leak protection, but you should still be aware of this.
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No-logging policy
- Mobile app
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Android and iOS
The volume of data you transmit
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Since your Internet traffic always goes through your ISP’s network first, your provider can see when you connect or disconnect from a VPN server and measure how much data you download or upload. Even if your real activity is hidden, they can still make assumptions about how you use the Internet.
For example, sudden spikes in data usage might suggest large downloads or video streaming. By tracking these patterns, your ISP can build a clear picture of your overall Internet habits and can choose to impose data caps or limit your speed. So while a VPN hides the details of your activity, it doesn’t hide the volume of your usage.
Location/IP address of your VPN server
Your ISP can also see the IP address of the VPN server you’re connected to, meaning it can identify its approximate location, estimate the provider, and estimate how far your traffic is routed. While this doesn’t reveal your browsing activity, it still gives your ISP enough context to take action if they want to.
For example, if you regularly connect to servers in a specific country, your ISP may assume that you are accessing geo-restricted content. Likewise, if you frequently use the same servers for bandwidth-intensive tasks, your ISP might decide to block or throttle those connections, although such measures are relatively rare.
The VPN provider you’re probably using
Most major VPN services use IP ranges belonging to well-known data centers. If your ISP notices that your traffic consistently comes from these ranges, they can link it to a specific VPN provider. In other words, your ISP can determine which VPN service you use if they want.
By knowing which VPN service you route your traffic through, your ISP could slow down connections to that VPN’s servers or even block the provider altogether, especially in regions where VPN usage is subject to strict limits. For me, this constitutes a blatant violation of my privacy and my personal freedom of choice.
While a VPN helps protect your online activity, you need to understand that it’s not a magical invisibility cloak. Providers don’t usually delve into details, but they can if they choose to – something to keep in mind. Choosing a reputable VPN service reduces the likelihood of such surveillance, making it worth investing in a reliable service.
This article was produced in partnership with NordVPN.
