WebRTC的一个例子

网页代码直接复制到下面（如果以上链接被墙，可以直接将下面代码保存文件，然后在浏览器打开即可，不支持IE浏览器）：
<!doctype html>
<html><head>
    <meta charset="utf-8">
    <title>Network IP Address via ipcalf.com</title>
</head><body>
Your network IP is: <h1 id=list>-</h1> Make the locals proud.

<script>

var RTCPeerConnection = window.webkitRTCPeerConnection || window.mozRTCPeerConnection;

if (RTCPeerConnection) (function () {
    var rtc = new RTCPeerConnection({iceServers:[]});
    if (1 || window.mozRTCPeerConnection) {
        rtc.createDataChannel('', {reliable:false});
    };
    
    rtc.onicecandidate = function (evt) {
        // convert the candidate to SDP so we can run it through our general parser
        // see https://twitter.com/lancestout/status/525796175425720320 for details
        if (evt.candidate) grepSDP("a="+evt.candidate.candidate);
    };
    rtc.createOffer(function (offerDesc) {
        grepSDP(offerDesc.sdp);
        rtc.setLocalDescription(offerDesc);
    }, function (e) { console.warn("offer failed", e); });
    
    
    var addrs = Object.create(null);
    addrs["0.0.0.0"] = false;
    function updateDisplay(newAddr) {
        if (newAddr in addrs) return;
        else addrs[newAddr] = true;
        var displayAddrs = Object.keys(addrs).filter(function (k) { return addrs[k]; });
        document.getElementById('list').textContent = displayAddrs.join(" or perhaps ") || "n/a";
    }
    
    function grepSDP(sdp) {
        var hosts = [];
        sdp.split('
').forEach(function (line) { // c.f. http://tools.ietf.org/html/rfc4566#page-39
            if (~line.indexOf("a=candidate")) {     // http://tools.ietf.org/html/rfc4566#section-5.13
                var parts = line.split(' '),        // http://tools.ietf.org/html/rfc5245#section-15.1
                    addr = parts[4],
                    type = parts[7];
                if (type === 'host') updateDisplay(addr);
            } else if (~line.indexOf("c=")) {       // http://tools.ietf.org/html/rfc4566#section-5.7
                var parts = line.split(' '),
                    addr = parts[2];
                updateDisplay(addr);
            }
        });
    }
})(); else {
    document.getElementById('list').innerHTML = "<code>ifconfig | grep inet | grep -v inet6 | cut -d" " -f2 | tail -n1</code>";
    document.getElementById('list').nextSibling.textContent = "In Chrome and Firefox your IP should display automatically, by the power of WebRTCskull.";
}

</script>

</body></html>