This tool is capable of checking if your VPN is leaking by running tests in a browser, and separately via your torrent client. Here’s a little more information on how it works:
How We Test for VPN Leaks
There are several different types of leak that the VPN leak test portion of the tool tests for:
The most basic test, but arguably the most important, our tool first detects your public IPv4 and IPv6 address before you connect to a VPN, and then again once connected. From there it simply compares the two sets of IP addresses. If they’re different then there is no IP leak.
Our tool makes a DNS request for a unique hostname in your browser when you don’t have a VPN 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.
If the connection is successful and the IP listed is your own IP, then a leak has occurred. If the IP listed is that of your VPN then everything is fine.
Your HTML5 geolocation will closely mirror your location in the real world, often even when your VPN is activated. This geolocation information is collected and made available via an API in your web browser.
Our tool asks for permission to access this data – should you grant it, it can then check your HTML5 geolocation and compare it to the location associated with your IP address. If those two locations are not a close match then there’s a chance that websites and services will know that you are not connecting from the location your VPN claims you are.
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 will tell 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 will tell you whether or not it appears on it. Data center IP addresses are commonly associated with VPNs, which means that this result is highly likely to come back as positive if you’re using one.
How We Test for Torrent IP Leaks
This tool can also check whether or not your IP address is leaking if you use a VPN while torrenting. Here’s what the torrent IP check tests for and how it works:
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’ll be able to see the IP address used – the same one that is visible to every peer in any torrent transfer you are a part of. If the IP address shown (both IPv4 and IPv6 where possible) matches that of the browser you started the test in, then it will confirm there is no leak.
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 will then cross-reference the IP address (or addresses) given with the IP address of your browser – no differences means no leaks.
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 then it warns you of a torrent DNS leak. These logs are deleted at the completion of the test.
If you are struggling to find a VPN which properly protects you, you can find an updated list of safe VPNs for torrenting here.