sudo vi /etc/apt/sources.list
deb http://download.webmin.com/download/repository sarge contrib deb http://webmin.mirror.somersettechsolutions.co.uk/repository sarge contrib
deb http://download.webmin.com/download/repository sarge contrib deb http://webmin.mirror.somersettechsolutions.co.uk/repository sarge contrib
sudo wget http://www.webmin.com/jcameron-key.asc
sudo apt-key add jcameron-key.asc
sudo apt update
sudo apt install webmin