IP, WebRTC & DNS Leak Test: Check Your VPN & Torrent IP

IP address leaks occur when your VPN fails to mask your personal IP address with one of its own.

An IP leak is a significant privacy risk, since your ISP and any websites you visit can see your real IP address.

If your IP address is leaking, your VPN is not working properly. Your privacy is not protected, and your online location exposed, rendering the VPN service worthless.

If your VPN is leaking, and you can’t fix it, we advise you to use one of our recommended best VPN services, instead.

IPv4 Leaks

The first test this tool runs is to retrieve your real public IP. That’s the IP address you present to everyone else on the internet.

70-80% of internet users use IPv4 addresses.

When you run this test with your VPN turned off, you’re using your ‘true’ IP address – the one assigned to your router or device by your ISP.

Your IP address is unique to you and can be used to both identify your device and find your real-world location.

When you switch your VPN on, your ‘true’ IP address is replaced by the IP address of the VPN server you’ve connected to.

If our tool doesn’t detect the IP address change, and shows the same IP as before, then your real IPv4 address is leaking.

This type of leak is rare, and is usually the result of your VPN’s failure to establish a connection.

IPv4 leaks allow your ISP and the websites you visit to monitor your web activity and your geo-location.

Streaming services like Netflix or BBC iPlayer use this information to block users from accessing content from other countries.

IPv6

IPv4 addresses are running out, and IPv6 addresses are the answer to this.About 20% of internet users have IPv6 addresses.

IPv6 is supported by all modern operating systems, but most websites and ISPs haven’t caught up yet.

This forces IPv6-compatible websites to support both IPv4 addresses and IPv6 addresses, depending on who is connecting to them.

Many VPN services still don’t support IPv6 connections, either.

Unless a VPN supports or actively blocks IPv6 connections, your IPv6 address is potentially exposed if you’re on an IPv6-enabled network.

IPv4 traffic will be routed through the VPN, but IPv6 traffic will be routed straight to your ISP – revealing your ‘true’ IPv6 address.

In our IPv6 test, you would see the same IPv6 address when you have your VPN turned on as when you have it turned off.

IPv6 leaks are just as dangerous as IPv4 leaks. Websites and applications will have access to your real location, and your ISP will know your internet history.

When you enter a URL into your browser to connect to a website, you first contact a DNS server which requests the IP address of that website. This server then sends your browser the ‘directions’ to the website you’re looking for.

If you’re not connected to a VPN, this process is carried out by your ISP’s DNS servers. Your DNS requests are plain text records of the websites you visit. Often, ISPs store these requests along with the IP addresses that make them.

A secure VPN encrypts these DNS queries, and routes them to private DNS servers.

However, if the requests are routed to your ISP’s DNS servers, it’s called a DNS leak. This exposes your browsing activity to your ISP, and other snoopers.

A DNS leak can occur if your VPN is manually configured, you have changed your computer’s settings, or your VPN service doesn’t protect against leaks.

Our VPN leak test checks if your HTTP and DNS requests are coming from the same network when the VPN is running. If they aren’t, your VPN is leaking.

If you’d like to see exactly which DNS servers you’re using, you can also use our dedicated tool to test your DNS server directly.

While DNS leaks won’t expose your IP address, they can reveal that things aren’t what they seem.

For example, Netflix uses DNS leaks to prevent geo-spoofing and block access to content abroad.

A leak-free DNS test result shows that your DNS and HTTP requests match, and appear to come from the same area. Other people can’t see the sites you’re browsing, but it doesn’t mean your real IP address is hidden.

Be aware that, when a VPN is running, this test can give a false alert if you’re using an anonymous DNS server not on our list of safe servers. Or, if your DNS and HTTP endpoints are located on different networks.

Web Real-Time Communication (WebRTC) is a web browser-based technology that enables video chat, voice calling, and P2P file sharing.

WebRTC is enabled by default in Firefox, Opera and Chrome.

Two devices communicating directly via WebRTC need to know each others’ IP address. Websites can therefore exploit your browser’s WebRTC functionality to capture your true IP address, even when using a VPN.

While any IP address leak threatens your privacy and anonymity, WebRTC leaks are particularly worrying because they’re often overlooked.

Make sure you use a VPN that protects against WebRTC leaks, as many don’t. We also recommend disabling WebRTC completely.

HTML5 geolocation, otherwise known as browser geolocation, is your device’s geo-coordinates as detected by a browser API (application programming interface).

The browser API detects your latitude and longitude coordinates by using either the device’s GPS, or information gained from the devices’ mobile/WIFI signal.

HTML5 geolocation can be very accurate, sometimes to a street-level, depending on the availability of device GPS and the quality of the mobile/WIFI signals.

A HTML5 leak exposes your actual location, even if your VPN is hiding your real IP address.

The good news is that HTML5 geolocation is strictly permission-based. Some websites prompt you with a browser pop up to ask permission to share your location.

If you deny this permission request, your geo-coordinates won’t be shared.

VPN browser extensions with built-in HTML5 Geolocation leak protection also help avoid this issue.

Flash Player is an outdated and insecure browser plugin which used to be the go-to for playing ‘rich media’ (embedded videos, browser games, etc.).

Flash causes serious security vulnerabilities if not regularly updated. It also has multiple weak points that leak your real IP address, even while using a proxy or VPN.

Luckily, Flash has now been entirely replaced by HTML5. Nevertheless, we recommend blocking Flash completely, or as an absolute minimum preventing it from starting automatically.

Our tool doesn’t check for Flash-related IP leaks, it just tests if Flash is enabled.

We also show you how to disable Flash on all browsers.

Tor is short for The Onion Router, a special software designed for extra-private web browsing.

You can access the Tor network by using the Tor Browser.

When you use the Tor Browser to visit a website, your request is relayed through multiple servers, known as nodes.

By the time your request reaches the final node (referred to as an exit node), and is sent on to the site you’re trying to visit, your IP address is practically untraceable.

There’s one giant central database which keeps track of all the IP addresses associated with Tor exit nodes. Our tool checks to see if yours is one of them.

Our Tor exit node test results will almost certainly come back as negative, unless you turned your home computer into a Tor exit node.

Our tool also checks whether your VPN has given you a residential or a data center IP address.

In other words, we can detect if your connection is typical of a home internet user (residential), or a VPN user (data center).

By examining the TCP and IP data packets sent, we can also detect how many steps a request took.

The number of requests can sometimes suggest the use of a proxy or a VPN. Requests from the same country take fewer steps than requests from the other side of the world.

Most proxies and VPNs open new requests and reset the hop counter, so they won’t be identified by this test.

Most data center IP tests come back positive when you using popular VPN services.

Torrent IP leaks occur when your torrenting activity is unintentionally linked to your true IP address, rather than your VPN IP address.

Our tool checks that your torrent client is using your VPN to send requests to a test torrent tracker, rather than them escaping the encrypted VPN tunnel.

We test TCP and UDP based tracker requests, which also ensures any IP address information shared is that of your VPN, not your own personal one.

What Is TCP?

TCP (or Transmission Control Protocol) is the most common protocol for transferring files when torrenting.

TCP is quick, and has minimal data overhead. However, there are a few scenarios in which your IP address may leak via a torrent TCP connection.

Some VPNs may only protect IPv4 traffic, leaving IPv6 exposed. Your torrent client may then make a connection over IPv6 to a peer, and your true IPv6 address is leaked.

If your torrent client is set to proxy via another machine on your local network – one not running a VPN – your real IP address may leak (either IPv4 or IPv6).

Finally, a leak can occur if your VPN hasn’t reset any active network connections when it was activated, and your torrent client was running at the time.

Any existing torrent traffic will likely still come from your true IPv4 or IPv6 address.

For an overview of the above risks, read our guide to torrenting safely.

What Is UDP?

User Datagram Protocol, much better known as UDP, is a carrier protocol used to transfer data packets while torrenting.

UDP is far less common than TCP, and as a result there’s a chance your VPN doesn’t support it.

If your VPN doesn’t support torrent UDP, then it won’t encrypt the transmission and your IP address may leak.

If a magnet link or a torrent file contains a tracker addressed with a domain name, your torrent client has to resolve this domain name to an IP address.

Our torrent DNS leak test determines the DNS server your torrent client is using.

If your torrent client is using your ISP’s DNS server instead of your VPN’s, your identity and P2P activity is at risk.

Our VPN leak test tool checks if your VPN is leaking by running tests in a browser, and separately via your torrent client.

Below is more information on how the tool works to test for different types of leaks.

IPv4/IPv6

Our tool first detects your public IPv4 and IPv6 address before you connect to a VPN, and then again once connected.

The tool then compares the two sets of IP addresses. If they’re different then there is no IP leak.

DNS

Our tool makes a DNS request for a unique hostname in your browser when your VPN isn’t running.

That hostname points at DNS servers hosted by us, and we log all the IPs that contact our server using that unique hostname.

The tool then repeats this process once you turn your VPN on.

The IPs that we see are the DNS servers that your browser is using, and we map these to the organization that owns those IPs.

If the organization is the same both before and after you turn on your VPN, then the tool will warn you of a DNS leak.

WebRTC

To detect a WebRTC leak we use JavaScript to create a peer-to-peer connection via your browser, utilizing the WebRTC API built into your browser.

The WebRTC API allows us to make STUN requests, which return both the public and local IP addresses for the browser, which JavaScript can then read.

If the connection is successful, and the IP address listed is your own, then there’s a leak.

However, if the IP address listed is not your own, then everything is fine.

HTML5 Geolocation

Your HTML5 geolocation closely mirrors your actual physical location.

This geolocation information is collected and made available via an API in your web browser.

Our tool asks for permission to access this data – if you grant our tool access, it can check your HTML5 geolocation and compare it to your IP address location.

If your IP and HTML5 locations aren’t a close match, there’s a chance websites and services will know you’re not really where your VPN server is.

Flash Player

Flash Player is an extreme security risk, and has now been officially discontinued.

Our tool runs a Javascript command to check a list of plugins running in your browser. If Flash is listed, then the tool warns you to disable it.

Tor Exit Node

Certain IP addresses are registered as exit nodes on the Tor network. These IP addresses are publicly known and listed.

Our tool cross-references your IP address with a database of all known Tor exit nodes, and tells you whether or not it appears on it.

Data Center IP Address

Some IP addresses are classified as data center IPs, rather than residential IPs.

Our tool cross-references your IP address with a database of known data center IPs, and tells you whether or not it’s listed on it.

Data center IP addresses are commonly associated with VPNs. Therefore, this result is highly likely to come back as positive.

Our tool also checks if your IP address is leaking if you’re using a VPN while torrenting.

Here’s what the torrent IP check tests for and how it works:

TCP

Once you download our TCP test file and add it to your torrent client, the torrent client will connect to our torrent tracker and we can see the IP address used – the same one visible to every peer in any torrent transfer you’re part of.

If the IP address shown (both IPv4 and IPv6 where possible) matches that of the browser you started the test in, then there is no leak.

UDP

The process for checking your IP address via UDP is exactly the same as with TCP: download the IPv4 and IPv6 UDP files and add them to your torrent client.

Our tool then cross-references the IP address (or addresses) given with the IP address of your browser – no differences means no leaks.

DNS

Our tool also checks for DNS leaks from your torrent client.

First, the tool makes a request for a domain (which points to our DNS server) in your browser.

Then, the torrent magnet file you downloaded makes the torrent client it was added to send its own request to our DNS server.

We log all the IPs we see making requests to our DNS server. If the address we log from your torrent client doesn’t match the one we log from your browser, there’s a torrent DNS leak.

Don’t worry, all IP addresses we log are deleted once the test is over.

If your P2P VPN keeps leaking, we recommend you switch to a secure VPN for torrenting.