Update the apt package index and install packages to allow apt to use a repository over HTTPS:

sudo apt-get update
sudo apt-get install \
	ca-certificates \
	gnupg \
	lsb-release
					

Add tuxnet24.de’s official GPG key:

wget -O - https://deb.tuxnet24.de/gpg.key | \
    sudo tee /etc/apt/trusted.gpg.d/tuxnet24.asc >/dev/null
					

Use the following command to set up the repository under ubuntu:

echo \
	"deb [trusted=yes signed-by=/etc/apt/trusted.gpg.d/tuxnet24.asc] https://deb.tuxnet24.de/ubuntu\
 $(lsb_release -cs 2>/dev/null) main" | sudo tee /etc/apt/sources.list.d/tuxnet24.list >/dev/null
					

Use the following command to set up the repository under debian:

echo \
	"deb [trusted=yes signed-by=/etc/apt/trusted.gpg.d/tuxnet24.asc] https://deb.tuxnet24.de/debian\
 $(lsb_release -cs 2>/dev/null) main" | sudo tee /etc/apt/sources.list.d/tuxnet24.list >/dev/null