大赛试题内容：

5.所有Linux主机root用户使用完全合格域名免密码ssh登录到其他Linux主机。

解答过程：

在linux-1上设置

[root@host-10-10-70-101 ~]# ssh-keygen

Generating public/private rsa key pair.

Enter file in which to save the key (/root/.ssh/id_rsa):

Created directory '/root/.ssh'.

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in /root/.ssh/id_rsa.