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