(tested on Qnap TS-219P)
1. login to web backend
2. go to App Center and install ipkg Optiware
4. login via ssh into backend:
filename: InstallScreen.sh
ipkg update; # update package repository ipkg install screen; # install screen ipkg install ncurses; # install ncurses library needed by the "screen" command
filename: EnableScreen.sh (everytime you login)
touch /var/run/utmp; # fix missing file export TERMINFO=/opt/share/terminfo; # set missing environment variables for TERM