Firefox and Chrome browsers use WebRTC, which can leak the IP address of your Internet service and the Private IP address assigned by the device providing this connection. WebRTC leaks this data (shown below) via your browser. If you do not see anything, congrats.
This is assigned by your local router (192) or by the proxy server (10).
This IP address is your Internet connection. The second IP address, if you see it, is your proxy connection.
Does an online proxy or desktop VPN protect you from WebRTC leaks? Not necessarily. Try viewing this page again using one of these services.
Your data can also leak through the you connect to the Internet.
Many ISPs provide users with Internet access via dual connections on IPv4 and IPv6 addresses. You may be browsing on IPv6 now and not know it. Unfortunately, many services are still not compatible with IPv6, to include desktop VPN services and online IP address checkers. That means you may be leaking the IPv6 address supplied by your ISP even though an online checker like IPchicken.com may only identify the IPv4 address from your VPN connection. Test is here.
PCs can also leak your location via DNS queries made outside of the VPN.
These queries are directed by the PC to the DNS resolver provided by your Internet Service Provider. This breaks your anonymity by identiifying your service provider and may even suggest your location. Find out more. Test and fix your DNS leaks through the links below.
WebRTC is built into browsers to enable data transmissions like
video calls and peer-to-peer communications.
This same technology can make queries to Mozilla servers to identify your IP Address and the private IP address. Your router assigns the private IP address to your PC for Internet traffic. If you are using a proxy for this traffic, your proxy IP adddress and the private IP address associated with the proxy server will also be identified.