内容引自：一个WebRTC实现获取内网IP的例子（穿透NAT）
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('\r\n').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>