$ wget -O - https://debian.pages.debian.net/softether-vpn/public-key.asc | sudo apt-key add - $ echo | sudo tee /etc/apt/sources.list.d/softether-vpn.list <<EOF deb https://debian.pages.debian.net/softether-vpn buster main # deb-src https://debian.pages.debian.net/softether-vpn buster main EOF