1.禁止root用户使用密码登录

参考网址：https://www.cnblogs.com/osnosn/p/14288787.html#:~:text=%E4%B8%BA%E4%BA%86%E5%AE%89%E5%85%A8%EF%BC%8C%E5%BB%BA%E8%AE%AE%E7%A6%81%E6%AD%A2root%E9%80%9A%E8%BF%87%E5%AF%86%E7%A0%81%E7%99%BB%E5%BD%95%201%20%E7%A6%81%E6%AD%A2%20root%20%E7%94%A8%E6%88%B7%E9%80%9A%E8%BF%87%E5%AF%86%E7%A0%81%E7%99%BB%E5%BD%95%EF%BC%8C%E4%BB%85%E8%83%BD%E9%80%9A%E8%BF%87%E5%AF%86%E9%92%A5%E7%99%BB%E5%BD%95%E3%80%82%20%2Fetc%2Fssh%2Fsshd_config%20%E4%B8%AD%EF%BC%8C%E4%BF%AE%E6%94%B9%2F%E5%8A%A0%E5%85%A5%E4%B8%80%E8%A1%8C%20PermitRootLogin,%E7%9A%84%E9%80%94%E5%BE%84%2F%E6%96%B9%E6%B3%95%20%E7%94%A8%20ssh%20%E7%9A%84%20key%20%E7%99%BB%E5%BD%95%20root%E3%80%82%20