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diff --git a/docs/setup/turn/coturn.md b/docs/setup/turn/coturn.md new file mode 100644 index 0000000000..a1bb1e934c --- /dev/null +++ b/docs/setup/turn/coturn.md @@ -0,0 +1,188 @@ +# coturn TURN server + +The following sections describe how to install [coturn](<https://github.com/coturn/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: + +```sh +sudo apt install coturn +``` + +This will install and start a systemd service called `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: + + ```sh + ./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: + + ```sh + make + sudo make install + ``` + +### Configuration + +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`: + + ```sh + 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. + +1. You will most likely want to configure `coturn` to write logs somewhere. The + easiest way is normally to send them to the syslog: + + ```sh + 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`. + +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 + + # 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 + ``` + +1. 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](https://github.com/vector-im/element-android/issues/1533) + [issues](https://github.com/vector-im/element-ios/issues/2712) as well as the underlying + [WebRTC issue](https://bugs.chromium.org/p/webrtc/issues/detail?id=11710). + Consider using a ZeroSSL certificate for your TURN server as a working alternative. + +1. 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.) + +1. 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. + +1. (Re)start the turn server: + + * If you used the Debian package (or have set up a systemd unit yourself): + ```sh + sudo systemctl restart coturn + ``` + + * If you built from source: + + ```sh + /usr/local/bin/turnserver -o + ``` |