---
title: 'eturnal'
date: 2024-02-25T19:46:23+01:00
weight: 1
---

As issues with coturn[^1] rendered it unusable most of the time, I researched 
another solution as drop-in service for STUN[^2] and TURN[^3].
[eturnal](https://eturnal.net/) is a modern, straightforward and written in
Erlang[^4]. Clients can connect using UDP, TCP, or TLS over IPv4 or IPv6. It
supports the mechanism described in an IETF draft[^5] for authentication.

{{< figure src="img/stun-turn-server.svg" alt="STUN/TURN server symbol"
    width="25%" >}}

## Basic setup

The [eturnal — UberLab 7 documentation](https://lab.uberspace.de/guide_eturnal/)
is used in addition to the [official documentation](https://eturnal.net/doc/)
to setup a basic service. Further adjustments are specified in the `eturnal.yml`
file.

## Logging level

To investigate configuration errors, I can change the `log_level` setting value
to `debug`, for example. Afterwards the eturnal service has to be restarted.

[^1]: [Issue #844](https://github.com/Uberspace/lab/issues/844) at GitHub
[^2]: Session Traversal Utilities for NAT
([STUN](https://en.wikipedia.org/wiki/STUN)) in the Wikipedia
[^3]: [Traversal Using Relays arount NAT](https://en.wikipedia.org/wiki/Traversal_Using_Relays_around_NAT)
(TURN) in the Wikipedia
[^4]: [Erlang](https://erlang.org/)/OTP website
[^5]: [REST API for Access to TURN Services](https://datatracker.ietf.org/doc/html/draft-uberti-behave-turn-rest-00)
specification as IETF draft