This is test.mosquitto.org. It hosts a publicly available Eclipse Mosquitto MQTT server/broker. MQTT is a very lightweight protocol that uses a publish/subscribe model. This makes it suitable for "machine to machine" messaging such as with low power sensors or mobile devices.
If you are interested in your own hosted instance of Mosquitto you should look at the Cedalo offering. Cedalo are the company that sponsor the main development of Mosquitto.
The server listens on the following ports:
The encrypted ports support TLS v1.3, v1.2 or v1.1 with x509 certificates and require client support to connect. For ports 8883 and 8884 you should use the certificate authority file (mosquitto.org.crt (PEM format), or mosquitto.org.der (DER format)) to verify the server connection. Ports 8081 and 8886 have a Lets Encrypt certificate, so you should use your system CA certificates or the appropriate Lets Encrypt CA certificate for verification.
Port 8884 requires clients to provide a certificate to authenticate their connection. You can generate your own certificate.
The configuration is available to view.
Unauthenticated clients have access to publish all topics. Clients can also subscribe to all topics with the exception of the literal # topic.
Connecting with the username wildcard will allow a subscription to # to succeed for 20 seconds before being automatically removed. This allows discovery of topics of interest.
The authenticated listeners require a username / password:
You are free to use it for any application, but please do not abuse or rely upon it for anything of importance. This server runs on an Intel Atom N2800, and as such is a low power device. It is not intended to demonstrate any performance characteristics.
You should also build your client to cope with the broker restarting.
If you have the mosquitto clients installed try:
Please don't publish anything sensitive, anybody could be listening.
This server is provided as a service for the community to do testing, but it is also extremely useful for testing the server. This means that it will often be running unreleased or experimental code and may not be as stable as you might hope. It may also be slow - the broker often runs under valgrind or perf. Finally, not all of the features may be available all of the time, depending on what testing is being done. In particular, websockets and TLS support are the most likely to be unavailable.
In general you can expect the server to be up and to be stable though.
Come and discuss the Mosquitto project on Slack (go to the Mosquitto channel).
If you do publish things to this server on a regular basis, please get in touch to satisfy my curiosity - there are lots of topics that look interesting but I know nothing about. I'm ral on the libera.chat #mqtt irc channel, or see the mosquitto source for contact details..
Please sponsor this service so we can move to a more powerful server.