From Chapter 1, Developing a WebRTC Application, you know that we used such a construction to get a new peer connection object:

var pc = RTCPeerConnection(pc_config, pc_constraints);

The pc_config parameter in the preceding code is a set of configuration options that we want to use while creating the peer connection object.

In the previous chapter, we used only the STUN technology, and usually, pc_config was something similar to the following:

var pc_config = {"iceServers":
       [{url:'stun:23.21.150.121'},
        {url:'stun:stun.l.google.com:19302'}]};

Here, you can see the two URLs of the ICE servers (we also discussed the ICE framework in Chapter 1, Developing a WebRTC Application), and they are both STUN servers.

In the same way, we can refer to a TURN server as follows:

{
  'iceServers': [
    {
      'url': 'stun:stun.l.google.com:19302'
    },
    {
      'url': 'turn:turn1.myserver.com:12345?transport=udp',
      'credential': 'UGJKBJHVYT',
      'username...