Root SFTP Remote Login
You may need to enable SSH, however, you are receiving a prompt, so most likely is already active, just in case:
sudo update-rc.d ssh enable
if security is high, edit /etc/ssh/sshd_config
sudo nano /etc/ssh/sshd_config
# comment
#PermitRootLogin without-password
# and add
PermitRootLogin yes
# and also
#StrictModes yes
StrictModes no #<-- THIS CHANGE MADE IT WORK
then, restart the ssh service:
sudo invoke-rc.d ssh restart
# or
sudo service ssh restart