Configure password-based login for root

By default, the SSH server denies password-based login for root. In /etc/ssh/sshd_config, change:

PermitRootLogin without-password

to

PermitRootLogin yes

And restart SSH:

sudo service ssh restart

Or, you can use SSH keys. If you don't have one, create one using ssh-keygen (stick to the default for the key, and skip the password if you feel like it). Then do sudo -s (or whatever your preferred method of becoming root is), and add an SSH key to /root/.ssh/authorized_keys:

cat /home/user/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys

in some case after change,


   PermitRootLogin yes 



must check this config : 
    DenyUsers root
    AllowUsers saeid


and to enable login must change to :
   #DenyUsers root
    AllowUsers root OtherUser