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diff --git a/docs/turn-howto.md b/docs/turn-howto.md new file mode 100644 index 0000000000..4a983621e5 --- /dev/null +++ b/docs/turn-howto.md @@ -0,0 +1,123 @@ +# Overview + +This document explains how to enable VoIP relaying on your Home Server with +TURN. + +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. + +The following sections describe how to install [coturn](<https://github.com/coturn/coturn>) (which implements the TURN REST API) and integrate it with synapse. + +## `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 installation + + # apt install coturn + +#### Source installation + +1. Download the [latest release](https://github.com/coturn/coturn/releases/latest) from github. Unpack it and `cd` into the directory. + +1. 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. + +1. Build and install it: + + make + make install + +1. 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 + +1. 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 + + # special case the turn server itself so that client->TURN->TURN->client flows work + 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 + + Ideally coturn should refuse to relay traffic which isn't SRTP; see + <https://github.com/matrix-org/synapse/issues/2009> + +1. Ensure your firewall allows traffic into the TURN server on the ports + you've configured it to listen on (remember to allow both TCP and UDP TURN + traffic) + +1. If you've configured coturn to support TLS/DTLS, generate or import your + private key and certificate. + +1. 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). +4. "`turn_allow_guests`": Whether to allow guest users to use the + TURN server. This is enabled by default, as otherwise VoIP will + not work reliably for guests. However, it does introduce a + security risk as it lets guests connect to arbitrary endpoints + without having gone through a CAPTCHA or similar to register a + real account. + +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 + turn_allow_guests: True + +After updating the homeserver configuration, you must restart synapse: + + cd /where/you/run/synapse + ./synctl restart + +..and your Home Server now supports VoIP relaying! |