Which Port Range Is Used By WebRTC Node Server

I have webrtc node server like as below.

var WebSocketServer = require('websocket').server;
var http = require('http');

var server = http.createServer(function(request, response) {
    // process HTTP request. Since we're writing just WebSockets server
    // we don't have to implement anything.
});
server.listen(1337, function() { });

// create the server
wsServer = new WebSocketServer({
    httpServer: server
});

// WebSocket server
wsServer.on('request', function(request) {
    var connection = request.accept(null, request.origin);

    // This is the most important callback for us, we'll handle
    // all messages from users here.
    connection.on('message', function(message) {
        if (message.type === 'utf8') {
            // process WebSocket message
        }
    });

    connection.on('close', function(connection) {
        // close user connection
    });
});

I wonder that which port range is used by node server. We can see one port in the code (1337). But i think node server uses one more port or port range because of video stream. How can i learn which ports are used by webrtc node server.