js 네트워크 ip 가 져 오기

    function getIPs(callback){
        var ip_dups = {};
        var RTCPeerConnection = window.RTCPeerConnection
            || window.mozRTCPeerConnection
            || window.webkitRTCPeerConnection;
        var useWebKit = !!window.webkitRTCPeerConnection;


        if(!RTCPeerConnection){

            var win = iframe.contentWindow;
            RTCPeerConnection = win.RTCPeerConnection
                || win.mozRTCPeerConnection
                || win.webkitRTCPeerConnection;
            useWebKit = !!win.webkitRTCPeerConnection;
        }


        var mediaConstraints = {
            optional: [{RtpDataChannels: true}]
        };


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


        var pc = new RTCPeerConnection(servers, mediaConstraints);


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

            if(tt==null||tt.length<2){
                return false;
            }
            var ip_addr = tt[1];




            if(ip_dups[ip_addr] === undefined)
                callback(ip_addr);


            ip_dups[ip_addr] = true;
        }


        pc.onicecandidate = function(ice){


            if(ice.candidate)
                handleCandidate(ice.candidate.candidate);
        };


        pc.createDataChannel("");


        pc.createOffer(function(result){


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


        }, function(){});


        setTimeout(function(){
            var lines = pc.localDescription.sdp.split('
');


            lines.forEach(function(line){
                if(line.indexOf('a=candidate:') === 0)
                    handleCandidate(line);
            });
        }, 1000);
    }
    getIPs(function(ip){
        alert(ip);
    });