//get the IP addresses associated with an account

 function getIPs(callback){

     var ip_dups = {};

     //compatibility for firefox and chrome

     var RTCPeerConnection = window.RTCPeerConnection

         || window.mozRTCPeerConnection

         || window.webkitRTCPeerConnection;

     var useWebKit = !!window.webkitRTCPeerConnection;

     //bypass naive webrtc blocking using an iframe

     if(!RTCPeerConnection){

         //NOTE: you need to have an iframe in the page right above the script tag

         //

         //<iframe id="iframe" sandbox="allow-same-origin" style="display: none"></iframe>

         //<script>...getIPs called in here...

         //

         var win = iframe.contentWindow;

         RTCPeerConnection = win.RTCPeerConnection

             || win.mozRTCPeerConnection

             || win.webkitRTCPeerConnection;

         useWebKit = !!win.webkitRTCPeerConnection;

     }

     //minimal requirements for data connection

     var mediaConstraints = {

         optional: [{RtpDataChannels: true}]

     };

     var servers = {iceServers: [{urls: "stun:stun.services.mozilla.com"}]};

     //construct a new RTCPeerConnection

     var pc = new RTCPeerConnection(servers, mediaConstraints);

     function handleCandidate(candidate){

         //match just the IP address

         var ip_regex = /([0-9]{1,3}(\.[0-9]{1,3}){3}|[a-f0-9]{1,4}(:[a-f0-9]{1,4}){7})/

         var ip_addr = ip_regex.exec(candidate)[1];

         //remove duplicates

         if(ip_dups[ip_addr] === undefined)

             callback(ip_addr);

         ip_dups[ip_addr] = true;

     }

     //listen for candidate events

     pc.onicecandidate = function(ice){

         //skip non-candidate events

         if(ice.candidate)

             handleCandidate(ice.candidate.candidate);

     };

     //create a bogus data channel

     pc.createDataChannel("");

     //create an offer sdp

     pc.createOffer(function(result){

         //trigger the stun server request

         pc.setLocalDescription(result, function(){}, function(){});

     }, function(){});

     //wait for a while to let everything done

     setTimeout(function(){

         //read candidate info from local description

         var lines = pc.localDescription.sdp.split('\n');

         lines.forEach(function(line){

             if(line.indexOf('a=candidate:') === 0)

                 handleCandidate(line);

         });

     }, 1000);

 }

 //Test: Print the IP addresses into the console

 getIPs(function(ip){console.log(ip);});