# Self-hosted TURN (coturn) for BizGaze Connect

Why: customers behind symmetric NAT / corporate firewalls / VPNs can't form a direct
WebRTC path, so screen share blanks out and disconnects. A TURN relay fixes it. We host
our own coturn on a VM we already own — flat cost, no per-GB billing.

## 1. VM prerequisites
- A VM with a **public IP** (your data-center VM is fine).
- A DNS A record, e.g. `turn.yourdomain.com` -> that public IP.
- A TLS cert for that name (Let's Encrypt): `certbot certonly --standalone -d turn.yourdomain.com`

## 2. Open firewall ports (on the VM and any edge firewall)
- `3478/udp` and `3478/tcp`  (STUN/TURN)
- `5349/tcp`                 (TURN over TLS)  — and `443/tcp` if you enable alt-tls
- `49152-65535/udp`          (relay range)

## 3. Configure
Edit `turnserver.conf`:
- `external-ip=` your VM's public IP
- `static-auth-secret=` a long random string (e.g. `openssl rand -hex 32`)
- `realm=` your domain
- `cert=` / `pkey=` paths to your Let's Encrypt cert

## 4. Run
```
docker compose up -d        # uses docker-compose.yml here
# or native: apt install coturn; copy this file to /etc/turnserver.conf; enable in /etc/default/coturn; systemctl enable --now coturn
```

## 5. Point the app at it (production env)
```
TURN_URLS=turn:turn.yourdomain.com:3478,turn:turn.yourdomain.com:3478?transport=tcp,turns:turn.yourdomain.com:5349?transport=tcp
TURN_SECRET=<the same static-auth-secret from turnserver.conf>
TURN_TTL=86400
```
The app's `/api/ice` mints short-lived credentials from `TURN_SECRET` automatically — no
permanent password is exposed, and outsiders can't reuse your relay. Restart the app.

## 6. Verify
- `GET https://<app>/api/ice` should return a `turn:`/`turns:` entry with a username + credential.
- Test page: https://webrtc.github.io/samples/src/content/peerconnection/trickle-ice/
  Add your `turns:turn.yourdomain.com:5349?transport=tcp` with the username/credential from
  `/api/ice`; you should see a candidate of type **relay**. If you do, restrictive networks
  are covered.