+ +

coturn TURN server

The following sections describe how to install coturn (which implements the TURN REST API).

`coturn` setup

Initial installation

The TURN daemon coturn is available from a variety of sources such as native package managers, or installation from source.

Debian and Ubuntu based distributions

Just install the debian package:

sudo apt install coturn
+

This will install and start a systemd service called coturn.

Source installation

+
Download the latest release from github. Unpack it and cd into the directory.
+
+
Configure it:
+
```
./configure
+
```
+
You may need to install libevent2: if so, you should do so in +the way recommended by your operating system. You can ignore +warnings about lack of database support: a database is unnecessary +for this purpose.
+
+
Build and install it:
+
```
make
+sudo make install
+
```
+

Configuration

+
Create or edit the config file in /etc/turnserver.conf. The relevant +lines, with example values, are:
+
```
use-auth-secret
+static-auth-secret=[your secret key here]
+realm=turn.myserver.org
+
```
+
See turnserver.conf for explanations of the options. One way to generate +the static-auth-secret is with pwgen:
+
```
pwgen -s 64 1
+
```
+
A realm must be specified, but its value is somewhat arbitrary. (It is +sent to clients as part of the authentication flow.) It is conventional to +set it to be your server name.
+
+
You will most likely want to configure coturn to write logs somewhere. The +easiest way is normally to send them to the syslog:
+
```
syslog
+
```
+
(in which case, the logs will be available via journalctl -u coturn on a +systemd system). Alternatively, coturn can be configured to write to a +logfile - check the example config file supplied with coturn.
+

Consider your security settings. TURN lets users request a relay which will +connect to arbitrary IP addresses and ports. The following configuration is +suggested as a minimum starting point:

# VoIP traffic is all UDP. There is no reason to let users connect to arbitrary TCP endpoints via the relay.
+no-tcp-relay
+
+# don't let the relay ever try to connect to private IP address ranges within your network (if any)
+# given the turn server is likely behind your firewall, remember to include any privileged public IPs too.
+denied-peer-ip=10.0.0.0-10.255.255.255
+denied-peer-ip=192.168.0.0-192.168.255.255
+denied-peer-ip=172.16.0.0-172.31.255.255
+
+# recommended additional local peers to block, to mitigate external access to internal services.
+# https://www.rtcsec.com/article/slack-webrtc-turn-compromise-and-bug-bounty/#how-to-fix-an-open-turn-relay-to-address-this-vulnerability
+no-multicast-peers
+denied-peer-ip=0.0.0.0-0.255.255.255
+denied-peer-ip=100.64.0.0-100.127.255.255
+denied-peer-ip=127.0.0.0-127.255.255.255
+denied-peer-ip=169.254.0.0-169.254.255.255
+denied-peer-ip=192.0.0.0-192.0.0.255
+denied-peer-ip=192.0.2.0-192.0.2.255
+denied-peer-ip=192.88.99.0-192.88.99.255
+denied-peer-ip=198.18.0.0-198.19.255.255
+denied-peer-ip=198.51.100.0-198.51.100.255
+denied-peer-ip=203.0.113.0-203.0.113.255
+denied-peer-ip=240.0.0.0-255.255.255.255
+
+# special case the turn server itself so that client->TURN->TURN->client flows work
+# this should be one of the turn server's listening IPs
+allowed-peer-ip=10.0.0.1
+
+# consider whether you want to limit the quota of relayed streams per user (or total) to avoid risk of DoS.
+user-quota=12 # 4 streams per video call, so 12 streams = 3 simultaneous relayed calls per user.
+total-quota=1200
+

+
Also consider supporting TLS/DTLS. To do this, add the following settings +to turnserver.conf:
+
```
# TLS certificates, including intermediate certs.
+# For Let's Encrypt certificates, use `fullchain.pem` here.
+cert=/path/to/fullchain.pem
+
+# TLS private key file
+pkey=/path/to/privkey.pem
+
+# Ensure the configuration lines that disable TLS/DTLS are commented-out or removed
+#no-tls
+#no-dtls
+
```
+
In this case, replace the turn: schemes in the turn_uris settings below +with turns:.
+
We recommend that you only try to set up TLS/DTLS once you have set up a +basic installation and got it working.
+
NB: If your TLS certificate was provided by Let's Encrypt, TLS/DTLS will +not work with any Matrix client that uses Chromium's WebRTC library. This +currently includes Element Android & iOS; for more details, see their +respective +issues as well as the underlying +WebRTC issue. +Consider using a ZeroSSL certificate for your TURN server as a working alternative.
+
+
Ensure your firewall allows traffic into the TURN server on the ports +you've configured it to listen on (By default: 3478 and 5349 for TURN +traffic (remember to allow both TCP and UDP traffic), and ports 49152-65535 +for the UDP relay.)
+
+
If your TURN server is behind NAT, the NAT gateway must have an external, +publicly-reachable IP address. You must configure coturn to advertise that +address to connecting clients:
+
```
external-ip=EXTERNAL_NAT_IPv4_ADDRESS
+
```
+
You may optionally limit the TURN server to listen only on the local +address that is mapped by NAT to the external address:
+
```
listening-ip=INTERNAL_TURNSERVER_IPv4_ADDRESS
+
```
+
If your NAT gateway is reachable over both IPv4 and IPv6, you may +configure coturn to advertise each available address:
+
```
external-ip=EXTERNAL_NAT_IPv4_ADDRESS
+external-ip=EXTERNAL_NAT_IPv6_ADDRESS
+
```
+
When advertising an external IPv6 address, ensure that the firewall and +network settings of the system running your TURN server are configured to +accept IPv6 traffic, and that the TURN server is listening on the local +IPv6 address that is mapped by NAT to the external IPv6 address.
+
+
(Re)start the turn server:
+
- +
  If you used the Debian package (or have set up a systemd unit yourself):
  +
```
sudo systemctl restart coturn
+
```
  +
- +
  If you built from source:
  +
```
/usr/local/bin/turnserver -o
+
```
  +
+

+ +

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