ssh-keygen -t rsa #-t means encryption method #The save path and short password confirmation will appear afterwards, just press Enter all the way
cd /root/.ssh
mv id_rsa.pub authorized_keys #renaming
Download id_rsa to local
Modify /etc/ssh/sshd_config
Disable password verification
PasswordAuthentication no
Enable key verification
RSAAuthentication yes
PubkeyAuthentication yes
Restart the SSH service
service sshd restart #centos system
service ssh restart #ubuntu system
/etc/init.d/ssh restart #debian system