Run apt-get install mumble-server
Configure /etc/mumble-server.ini to expose ice-endpoint by making sure the settings looks like this:
ice="tcp -h 127.0.0.1 -p 6502"
#icesecretwrite=
You will need to restart the mumble-server by running sudo systemctl restart mumble-server after the configuration change
You also need to install the ice extension for php and generate a class for Murmur (mumble-server)
apt-get install php5-cli php-zeroc-ice libzeroc-ice35
cd /usr/share/slice/
slice2php Murmur.ice -I//usr/share/Ice-3.5.1/slice
Copy the newly generated Murmur.php to the folder where you will have idle.php.
You probably need to modify the idle.php-script to have your AFK-channel ID configured correctly.
To have the script run every minute, add the following to your cron.d or crontab:
* * * * * php /path/to/idle.php 2>&1 > /dev/null
This expects the idle.php to be installed in the folder /path/to alongside Murmur.php