在root目录下输入ssh-keygen -t rsa -b 4096，然后根据需要输入证书文件保存路径和名称，以下采用默认名称
[root@vultr ~]# ssh-keygen -t rsa -b 4096 Generating public/private rsa key pair. Enter file in which to save the key (/root/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: 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: b4:08:a0:58:8a:23:1a:bb:81:2b:c6:38:3f:16:05:b6 root@vultr.guest The key's randomart image is: +--[ RSA 4096]----+ | o | |o+o. | |O. o. . | |++E .. o . | |= . . S | |o+. | |*o . | |ooo | | ... | +-----------------+
cd到root/.ssh/目录下，执行cp id_rsa.pub authorized_keys，因为openssh缺省的文件名是authorized_keys。
将id_rsa文件下载到本地，以Xshell为例，在新建会话时方法下拉框中选择public_key，用户名输入root，然后点击浏览导入刚刚下载的证书，密码为刚刚设置的paraphrase
