Permit root login in SSH

Simply adding a password for root is not enough for Ubuntu 14.04 Server.

You also need to edit /etc/ssh/sshd_config, and comment out the following line:

PermitRootLogin without-password

Just below it, add the following line:

PermitRootLogin yes

Then restart SSH:

service ssh restart

References :

http://askubuntu.com/questions/469143/how-to-enable-ssh-root-access-on-ubuntu-14-04