Generate key, copy key to server and finally ssh passwordless into your server.
ssh-kegen -t rsa
ssh-copy-id root@ip
ssh root@ip
View your generated key with:
cat /home/user/.ssh/id_rsa //local
cat /home/user/.ssh/authorized_keys //server
To disable password authentication permanently you have to edit the ssh config. Be sure to first backup before editing. Now just set PasswordAuthentication to “no” in your config and restart the ssh daemon.
cp /etc/ssh/sshd_config /etc/ssh/sshd_config_bak
nano /etc/ssh/sshd_config
service ssh restart