切換到使用者home目錄，比如當前使用者目錄
cd ~/.ssh/
生成秘鑰
ssh-keygen -t rsa
提示輸入秘鑰通訊密碼，如果不需要密碼可以自己回車，預設空密碼
提示生成私鑰檔案id_rsa和公鑰檔案id_rsa.pub
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
寫入公鑰到authorized_keys
cat id_rsa.pub >> authorized_keys
設定秘鑰檔案和目錄許可權
chmod 600 authorized_keys
chmod 700 ~/.ssh
配置sshd，開啟秘鑰登入選項
vim /etc/ssh/sshd_config
RSAAuthentication yes
PubkeyAuthentication yes
重啟sshd服務
systemctl restart sshd
下載私鑰檔案id_rsa，這個私鑰檔案可用於ssh客戶端連線，配置好ssh客戶端完成聯通測試。測試透過，配置sshd，禁用密碼登入選項
vim /etc/ssh/sshd_config
PasswordAuthentication no
重啟sshd服務
systemctl restart sshd
配置ssh命令使用pem秘鑰登入