yum install安装软件时在downloading时报错，如下图
解决方法：
阿里云官方拉取的镜像文件内容为http地址，需换成https
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
sed -i 's/http/https/g' /etc/yum.repos.d/CentOS-Base.repo服务器租用托管，机房租用托管，主机租用托管，https://www.e1idc.com
