备份yum源
cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
安装国内源
#阿里云源
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
#网易源
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo