Remmina

Для Debian9 Stretch
https://www.remmina.org/wp/the[..]on-debian-9-stretch/

echo 'deb http://ftp.debian.org/debian stretch-backports main' | sudo tee --append /etc/apt/sources.list.d/stretch-backports.list >> /dev/null
sudo apt update
sudo apt install -t stretch-backports remmina remmina-plugin-rdp remmina-plugin-secret libfreerdp-plugins-standard