xshell 突然连接不上虚拟机了，估计是异常退出虚拟机导致的
Connecting to 192.168.3.10:22... Could not connect to '192.168.3.10' (port 22): Connection failed. Type `help' to learn how to use Xshell prompt.
查看sshd服务状态：systemctl status sshd
systemctl enable命令=激活开机启动
启动sshd服务：systemctl status sshd
依然失败
启动sshd调试模式：/usr/sbin/sshd -d
报错：
/var/empty/sshd must be ...
执行赋权操作：
chmod 744 /var/empty/sshd
再次启动调试模式不再报错，重启sshd 服务：
systemctl restart sshd
结果
