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When troubleshooting WebRTC connectivity issues, it is helpful to confirm whether or not the client can successfully reach the necessary STUN server. Having a proper connection to STUN is a critical component to advertising your public IP address and chosen port to our webRTC resources; especially in the case of NAT. If you’d like to learn more about STUN, this article is very informative.

This guide provides a quick set of instructions to validate reachability of a STUN server. There are two methods of testing; 'Using the Browser Console” and the “webrtc.github.io” method.

Info

Sharpen webRTC leverages the Google STUN servers accessible via stun.l.google.com:19302. The methods below test against the same endpoint Sharpen uses.

webrtc.github.io

The following tool is not managed by Sharpen, so it should be noted that its usefulness may change.

  1. Navigate to Trickle ICE (webrtc.github.io)

  2. Click the “Gather Candidates” button

    Image Added

  3. Evaluate the results

    Image Added

  4. If you do not see a reflexive reference to your public IP address, then you’re having issues connecting to the Google STUN server.

Using the Browser Console

  1. Open a chrome web browser

  2. Open the inspector (right-click>inspect)

  3. Choose the ‘Console’ tab

  4. paste Paste in this block of code

    Code Block
    const iceServers = [
    {
        urls: 'stun:stun.l.google.com:19302?transport=udp'
    },
];

const pc = new RTCPeerConnection({
	iceServers
});

pc.onicecandidate = (e) => {
    if (!e.candidate) return;

    // Display candidate string e.g
    // candidate:842163049 1 udp 1677729535 XXX.XXX.XX.XXXX 58481 typ srflx raddr 0.0.0.0 rport 0 generation 0 ufrag sXP5 network-cost 999
    console.log(e.candidate.candidate);

    if(e.candidate.type == "srflx"){
        console.log("The STUN server is reachable!");
        console.log(`   Your Public IP Address is: ${e.candidate.address}`);
    }
};

// Log errors:
// Remember that in most of the cases, even if its working, you will find a STUN host lookup received error
// Chrome tried to look up the IPv6 DNS record for server and got an error in that process. However, it may still be accessible through the IPv4 address
pc.onicecandidateerror = (e) => {
    console.error(e);
};

pc.createDataChannel('stun-test');
pc.createOffer().then(offer => pc.setLocalDescription(offer));

  5. Press enter

  6. Observe the response

...