171 lines
7.1 KiB
Markdown
171 lines
7.1 KiB
Markdown
# eturnal TURN server
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The following sections describe how to install [eturnal](<https://github.com/processone/eturnal>)
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(which implements the TURN REST API).
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## `eturnal` setup
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### Initial installation
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The `eturnal` TURN server implementation is available from a variety of sources
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such as native package managers, binary packages, installation from source or
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[container image](https://eturnal.net/documentation/code/docker.html). They are
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all described [here](https://github.com/processone/eturnal#installation).
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Quick-Test instructions in a [Linux Shell](https://github.com/processone/eturnal/blob/master/QUICK-TEST.md)
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or with [Docker](https://github.com/processone/eturnal/blob/master/docker-k8s/QUICK-TEST.md)
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are available as well.
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### Configuration
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After installation, `eturnal` usually ships a [default configuration file](https://github.com/processone/eturnal/blob/master/config/eturnal.yml)
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here: `/etc/eturnal.yml` (and, if not found there, there is a backup file here:
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`/opt/eturnal/etc/eturnal.yml`). It uses the (indentation-sensitive!) [YAML](https://en.wikipedia.org/wiki/YAML)
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format. The file contains further explanations.
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Here are some hints how to configure eturnal on your [host machine](https://github.com/processone/eturnal#configuration)
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or when using e.g. [Docker](https://eturnal.net/documentation/code/docker.html).
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You may also further deep dive into the [reference documentation](https://eturnal.net/documentation/).
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`eturnal` runs out of the box with the default configuration. To enable TURN and
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to integrate it with your homeserver, some aspects in `eturnal`'s default configuration file
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must be edited:
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1. Homeserver's [`turn_shared_secret`](../../usage/configuration/config_documentation.md#turn_shared_secret)
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and eturnal's shared `secret` for authentication
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Both need to have the same value. Uncomment and adjust this line in `eturnal`'s
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configuration file:
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```yaml
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secret: "long-and-cryptic" # Shared secret, CHANGE THIS.
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```
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One way to generate a `secret` is with `pwgen`:
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```sh
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pwgen -s 64 1
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```
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1. Public IP address
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If your TURN server is behind NAT, the NAT gateway must have an external,
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publicly-reachable IP address. `eturnal` tries to autodetect the public IP address,
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however, it may also be configured by uncommenting and adjusting this line, so
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`eturnal` advertises that address to connecting clients:
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```yaml
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relay_ipv4_addr: "203.0.113.4" # The server's public IPv4 address.
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```
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If your NAT gateway is reachable over both IPv4 and IPv6, you may
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configure `eturnal` to advertise each available address:
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```yaml
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relay_ipv4_addr: "203.0.113.4" # The server's public IPv4 address.
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relay_ipv6_addr: "2001:db8::4" # The server's public IPv6 address (optional).
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```
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When advertising an external IPv6 address, ensure that the firewall and
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network settings of the system running your TURN server are configured to
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accept IPv6 traffic, and that the TURN server is listening on the local
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IPv6 address that is mapped by NAT to the external IPv6 address.
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1. Logging
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If `eturnal` was started by systemd, log files are written into the
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`/var/log/eturnal` directory by default. In order to log to the [journal](https://www.freedesktop.org/software/systemd/man/systemd-journald.service.html)
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instead, the `log_dir` option can be set to `stdout` in the configuration file.
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1. Security considerations
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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, [see also the official documentation](https://eturnal.net/documentation/#blacklist):
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```yaml
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## Reject TURN relaying from/to the following addresses/networks:
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blacklist: # This is the default blacklist.
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- "127.0.0.0/8" # IPv4 loopback.
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- "::1" # IPv6 loopback.
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- recommended # Expands to a number of networks recommended to be
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# blocked, but includes private networks. Those
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# would have to be 'whitelist'ed if eturnal serves
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# local clients/peers within such networks.
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```
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To whitelist IP addresses or specific (private) networks, you need to **add** a
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whitelist part into the configuration file, e.g.:
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```yaml
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whitelist:
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- "192.168.0.0/16"
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- "203.0.113.113"
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- "2001:db8::/64"
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```
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The more specific, the better.
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1. TURNS (TURN via TLS/DTLS)
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Also consider supporting TLS/DTLS. To do this, adjust the following settings
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in the `eturnal.yml` configuration file (TLS parts should not be commented anymore):
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```yaml
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listen:
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- ip: "::"
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port: 3478
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transport: udp
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- ip: "::"
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port: 3478
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transport: tcp
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- ip: "::"
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port: 5349
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transport: tls
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## TLS certificate/key files (must be readable by 'eturnal' user!):
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tls_crt_file: /etc/eturnal/tls/crt.pem
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tls_key_file: /etc/eturnal/tls/key.pem
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```
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In this case, replace the `turn:` schemes in homeserver's `turn_uris` settings
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with `turns:`. More is described [here](../../usage/configuration/config_documentation.md#turn_uris).
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We recommend that you only try to set up TLS/DTLS once you have set up a
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basic installation and got it working.
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NB: If your TLS certificate was provided by Let's Encrypt, TLS/DTLS will
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not work with any Matrix client that uses Chromium's WebRTC library. This
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currently includes Element Android & iOS; for more details, see their
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[respective](https://github.com/element-hq/element-android/issues/1533)
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[issues](https://github.com/element-hq/element-ios/issues/2712) as well as the underlying
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[WebRTC issue](https://bugs.chromium.org/p/webrtc/issues/detail?id=11710).
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Consider using a ZeroSSL certificate for your TURN server as a working alternative.
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1. Firewall
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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 TURN
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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. Reload/ restarting `eturnal`
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Changes in the configuration file require `eturnal` to reload/ restart, this
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can be achieved by:
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```sh
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eturnalctl reload
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```
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`eturnal` performs a configuration check before actually reloading/ restarting
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and provides hints, if something is not correctly configured.
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### eturnalctl opterations script
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`eturnal` offers a handy [operations script](https://eturnal.net/documentation/#Operation)
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which can be called e.g. to check, whether the service is up, to restart the service,
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to query how many active sessions exist, to change logging behaviour and so on.
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Hint: If `eturnalctl` is not part of your `$PATH`, consider either sym-linking it (e.g. ´ln -s /opt/eturnal/bin/eturnalctl /usr/local/bin/eturnalctl´) or call it from the default `eturnal` directory directly: e.g. `/opt/eturnal/bin/eturnalctl info`
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