WebRTC漏えいテスト
WebRTCはウェブページが直接接続を確立するための仕組みで、そのためにブラウザは自分のアドレスを収集します。このテストは、ページがその方法で何を知り得るかを示します。
テストでは、ビデオ通話のページと同様に、CloudflareのパブリックSTUNサーバー（stun.cloudflare.com、ポート3478）に見えているアドレスを問い合わせます。そのためCloudflareにはあなたのアドレスが見えますが、当サイトのサーバーには何も送信しません。
このテキストはまだ日本語で提供されていません。翻訳が公開されるまで英語で表示しています。
WebRTC lets a web page open direct audio, video and data connections, the technology behind browser video calls. To find a direct path between two devices, the browser gathers candidates: its local addresses, and its public address as seen by a STUN server on the internet.
Before 2019, any page could read your local network addresses this way. Modern browsers hide them behind random .local names (mDNS), so a page sees something like 8f3c….local instead of 192.168.1.23.
The public address is the interesting part for VPN users. Normally it is the same address every website sees. If the VPN only tunnels some traffic, WebRTC can reveal the address of your real connection. This test gathers candidates exactly as a call would, using Cloudflare’s public STUN server, and compares the public address with the one this page sees.
よくある質問
Who sees my address during the test?
Cloudflare's STUN server (stun.cloudflare.com), which has to see an address to report it, just as in any video call. Nothing from the test is sent to our server.
How do I stop a WebRTC leak?
Use a VPN app that routes all traffic, including UDP, through the tunnel; many have a WebRTC or leak-protection setting. Firefox can disable WebRTC entirely (media.peerconnection.enabled in about:config).
The test shows an IPv6 address I did not expect.
Some VPNs tunnel only IPv4. If WebRTC shows a public IPv6 address from your own provider, your IPv6 traffic bypasses the VPN.