Download the MQTT plugin and part of that is the installation of the MQTT broker. Here installed a broker way before tinkering with Home Assistant.
Here also have an MQTT broker running on a micro travel router modded with OpenWRT and added Python to it. Runs well.
You can run MQTT broker on Linux, Windows, iOS. Just about any device that you keep on 24/7. BTW HA has to run 24/7 and cannot go to sleep if you want to use it for automation. Here utilize HA Alexia Media plugin to monitor all of the Alexa devices in this house and house #2.
Read the MQTT wiki here ==>
MQTT wiki
I am using it today for Wifi switches / devices modded with Tasmota / Espurna...Ring...etc...house #2 automation is all MQTT / locally managed WiFi (Tasmota) switches / locally managed Ring alarm (via cloud)- IE: no X10, UPB, ZWave or Zigbee in house #2. Currently running HA and HS on a Pine64 arm based computer and switching over to an Intel Jetway micro computer.
In the beginning here also utilized
Node Red
First generation of the
OmniBridgeLink used MQTT. I was using it with Smartthings hub way long time ago...and before that to sync my OmniPro 2 clock.
For Linux it is:
1 - sudo update
2 - sudo apt install mqtt
Which is different is you are running HASSIO (old name) on a RPi.
If the endeavor is is a tad high learning curve wise....you can also use Homeseer and the Omni Plugin. It runs on Windows or Linux.
You can run both Homeseer and the Omni Plugin on an RPi and the Omnilinkbridge without HA talking MQTT.
The Homeseer Omni Plugin works well with the OmniPro panel.
Run them both and see which one you like better.