第一步

ssh-keygen -t rsa
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

第二步

修改 /etc/ssh/sshd_config 三处

1. PubkeyAuthentication yes
2. AuthorizedKeysFile ~/.ssh/authorized_keys
3. PasswordAuthentication no

最后

service sshd reload