The host ‘xxx.xxx.xxx.xxx’ is unreachable.the host may be down,or there may be a problem with the network connection.Sometimes such problems can also be caused by a misconfigured firewall。 原因: ubuntu缺省安装了openssh-client 解决方法 乌班图命令框安装ssh的服务器端 sudo apt install openssh-server 再开启SSH连接就OK了