Edit ssh config and disable root logon via ssh :

sudo vi /etc/ssh/sshd_config

and set “PermitRootLogin” to no.

If you get an error about the ssh_host_dsa_key or ssh_host_rsa_key not being found, generate the keys and try again

Starting OpenBSD Secure Shell server: sshd
Could not load host key: /etc/ssh/ssh_host_dsa_key
Could not load host key: /etc/ssh/ssh_host_rsa_key

Generate host keys :

ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key
ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key

Start sshd (“sudo /etc/init.d/ssh start”)
If you want to enable ssh to start at boot time, run update-rc.d ssh defaults