160 lines
5.6 KiB
Markdown
160 lines
5.6 KiB
Markdown
# Overview
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This document explains how to enable VoIP relaying on your Home Server with
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TURN.
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The synapse Matrix Home Server supports integration with TURN server via the
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[TURN server REST API](<http://tools.ietf.org/html/draft-uberti-behave-turn-rest-00>). This
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allows the Home Server to generate credentials that are valid for use on the
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TURN server through the use of a secret shared between the Home Server and the
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TURN server.
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The following sections describe how to install [coturn](<https://github.com/coturn/coturn>) (which implements the TURN REST API) and integrate it with synapse.
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## Requirements
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For TURN relaying with `coturn` to work, it must be hosted on a server/endpoint with a public IP.
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Hosting TURN behind a NAT (even with appropriate port forwarding) is known to cause issues
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and to often not work.
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## `coturn` setup
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### Initial installation
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The TURN daemon `coturn` is available from a variety of sources such as native package managers, or installation from source.
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#### Debian installation
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Just install the debian package:
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```sh
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apt install coturn
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```
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This will install and start a systemd service called `coturn`.
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#### Source installation
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1. Download the [latest release](https://github.com/coturn/coturn/releases/latest) from github. Unpack it and `cd` into the directory.
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1. Configure it:
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./configure
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> You may need to install `libevent2`: if so, you should do so in
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> the way recommended by your operating system. You can ignore
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> warnings about lack of database support: a database is unnecessary
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> for this purpose.
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1. Build and install it:
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make
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make install
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### Configuration
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1. Create or edit the config file in `/etc/turnserver.conf`. The relevant
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lines, with example values, are:
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use-auth-secret
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static-auth-secret=[your secret key here]
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realm=turn.myserver.org
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See `turnserver.conf` for explanations of the options. One way to generate
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the `static-auth-secret` is with `pwgen`:
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pwgen -s 64 1
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1. Consider your security settings. TURN lets users request a relay which will
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connect to arbitrary IP addresses and ports. The following configuration is
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suggested as a minimum starting point:
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# VoIP traffic is all UDP. There is no reason to let users connect to arbitrary TCP endpoints via the relay.
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no-tcp-relay
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# don't let the relay ever try to connect to private IP address ranges within your network (if any)
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# given the turn server is likely behind your firewall, remember to include any privileged public IPs too.
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denied-peer-ip=10.0.0.0-10.255.255.255
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denied-peer-ip=192.168.0.0-192.168.255.255
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denied-peer-ip=172.16.0.0-172.31.255.255
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# special case the turn server itself so that client->TURN->TURN->client flows work
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allowed-peer-ip=10.0.0.1
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# consider whether you want to limit the quota of relayed streams per user (or total) to avoid risk of DoS.
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user-quota=12 # 4 streams per video call, so 12 streams = 3 simultaneous relayed calls per user.
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total-quota=1200
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1. Also consider supporting TLS/DTLS. To do this, add the following settings
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to `turnserver.conf`:
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# TLS certificates, including intermediate certs.
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# For Let's Encrypt certificates, use `fullchain.pem` here.
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cert=/path/to/fullchain.pem
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# TLS private key file
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pkey=/path/to/privkey.pem
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1. Ensure your firewall allows traffic into the TURN server on the ports
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you've configured it to listen on (By default: 3478 and 5349 for the TURN(s)
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traffic (remember to allow both TCP and UDP traffic), and ports 49152-65535
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for the UDP relay.)
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1. (Re)start the turn server:
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* If you used the Debian package (or have set up a systemd unit yourself):
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```sh
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systemctl restart coturn
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```
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* If you installed from source:
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```sh
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bin/turnserver -o
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```
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## Synapse setup
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Your home server configuration file needs the following extra keys:
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1. "`turn_uris`": This needs to be a yaml list of public-facing URIs
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for your TURN server to be given out to your clients. Add separate
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entries for each transport your TURN server supports.
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2. "`turn_shared_secret`": This is the secret shared between your
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Home server and your TURN server, so you should set it to the same
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string you used in turnserver.conf.
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3. "`turn_user_lifetime`": This is the amount of time credentials
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generated by your Home Server are valid for (in milliseconds).
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Shorter times offer less potential for abuse at the expense of
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increased traffic between web clients and your home server to
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refresh credentials. The TURN REST API specification recommends
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one day (86400000).
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4. "`turn_allow_guests`": Whether to allow guest users to use the
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TURN server. This is enabled by default, as otherwise VoIP will
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not work reliably for guests. However, it does introduce a
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security risk as it lets guests connect to arbitrary endpoints
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without having gone through a CAPTCHA or similar to register a
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real account.
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As an example, here is the relevant section of the config file for matrix.org:
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turn_uris: [ "turn:turn.matrix.org:3478?transport=udp", "turn:turn.matrix.org:3478?transport=tcp" ]
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turn_shared_secret: "n0t4ctuAllymatr1Xd0TorgSshar3d5ecret4obvIousreAsons"
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turn_user_lifetime: 86400000
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turn_allow_guests: True
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After updating the homeserver configuration, you must restart synapse:
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* If you use synctl:
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```sh
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cd /where/you/run/synapse
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./synctl restart
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```
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* If you use systemd:
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```
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systemctl restart synapse.service
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```
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..and your Home Server now supports VoIP relaying!
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