synapse/docs/turn-howto.rst

How to enable VoIP relaying on your Home Server with TURN

Overview

The synapse Matrix Home Server supports integration with TURN server via the TURN server REST API (http://tools.ietf.org/html/draft-uberti-behave-turn-rest-00). This allows the Home Server to generate credentials that are valid for use on the TURN server through the use of a secret shared between the Home Server and the TURN server.

This document describes how to install coturn (https://github.com/coturn/coturn) which also supports the TURN REST API, and integrate it with synapse.

coturn Setup

You may be able to setup coturn via your package manager, or set it up manually using the usual configure, make, make install process.

1. Check out coturn:

   git clone https://github.com/coturn/coturn.git coturn
   cd coturn

2. 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.

3. Build and install it:

   make
   make install

4. Create or edit the config file in /etc/turnserver.conf. The relevant lines, with example values, are:

   lt-cred-mech
   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

5. Ensure youe firewall allows traffic into the TURN server on the ports you've configured it to listen on (remember to allow both TCP and UDP if you've enabled both).

6. If you've configured coturn to support TLS/DTLS, generate or import your private key and certificate.

7. Start the turn server:

   bin/turnserver -o

synapse Setup

Your home server configuration file needs the following extra keys:

1. "turn_uris": This needs to be a yaml list of public-facing URIs for your TURN server to be given out to your clients. Add separate entries for each transport your TURN server supports.
2. "turn_shared_secret": This is the secret shared between your Home server and your TURN server, so you should set it to the same string you used in turnserver.conf.
3. "turn_user_lifetime": This is the amount of time credentials generated by your Home Server are valid for (in milliseconds). Shorter times offer less potential for abuse at the expense of increased traffic between web clients and your home server to refresh credentials. The TURN REST API specification recommends one day (86400000).

As an example, here is the relevant section of the config file for matrix.org:

turn_uris: [ "turn:turn.matrix.org:3478?transport=udp", "turn:turn.matrix.org:3478?transport=tcp" ]
turn_shared_secret: n0t4ctuAllymatr1Xd0TorgSshar3d5ecret4obvIousreAsons
turn_user_lifetime: 86400000

Now, restart synapse:

cd /where/you/run/synapse
./synctl restart

...and your Home Server now supports VoIP relaying!