I created a script to detect all devices on the network. Installation instructions are here: https://github.com/thijsdebets/networkdetectz/wiki It uses a combination of arpscan, ping and even supports bluetooth detection. I use it very succesfull to detect who is at home and to set the lights to TV ...

You might need to disable MySQL in Config.cfg:

[mysql]
# Enable for exporting to a mysql database
mysql_enabled = false
# Host where the mysql server is active
mysql_host = 127.0.0.1
mysql_user =
mysql_pass =
mysql_db =

[pvout]

I wrote a shell script for my Raspberry Pi 2 to do this. It uses arp-scan and a table to match discovered mac-addresses to actual dynamic ip-addresses and switches devices off on Domoticz when they are not discovered any more for a couple of minutes. Install arp-scan: sudo apt-get install arp-scan ...