网易源设置帮助 http://mirrors.163.com/.help/centos.html。
备份
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
下载新源
cd /etc/yum.repos.d
wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
生成缓存
yum clean all
yum makecache
2017/04/01
CentOS 7 设置国内源