1.- On client computer, create private/public keys: Accept all defaults
ssh-keygen -t rsa
2.- copy public key to remote host
ssh-copy-id -i ~/.ssh/id_rsa.pub remotehost
3. test
ssh remotehost
4.- Disable Password login, edit /etc/ssh_config
Find PasswordAuthentication
Change it from #PasswordAuthentication yes to PasswordAuthentication no
5.- Restart sshd
systemctl restart sshd