linux中实现密钥对验证登录（私钥口令）的方法是什么？

准备客户机测试环境

为客户机的用户root建立SSH密钥对

使用ssh-keygen创建密钥对，将私钥口令设为空（直接回车）：

[root@client ~]$ 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):                    //直接回车将口令设为空
Enter same passphrase again:                                             //再次回车确认
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
63:6e:cf:45:f0:56:e2:89:6f:62:64:5a:5e:fd:68:d2
The key's randomart image is:
+--[ RSA 2048]----+
| |
| |
| . . . |
| = = |
| S = B . |
| o B = . o |
| + + = E .|
| . + + o |
| o |
+-----------------+
[root@client ~]$ ls -lh ~/.ssh/id_rsa*                 //确认密钥对文件
-rw-------. 1 root root 1.8K 8月 15 10:35 /root/.ssh/id_rsa
-rw-r--r--. 1 root root 403 8月 15 10:35 /root/.ssh/id_rsa.pub