在CentOS 6.3，yum install报错
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again，需要安装epel源。
解决方法：
一句话：把/etc/yum.repos.d/epel.repo，文件第3行注释去掉，把第四行注释掉。具体如下：
打开/etc/yum.repos.d/epel.repo，将[epel]
name=ExtraPackagesforEnterpriseLinux6-$basearch
#baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch
修改为
[epel]
name=ExtraPackagesforEnterpriseLinux6-$basearch
baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch
#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch
再清理源，重新安装
yum clean all
yum install -y 需要的包
如果还是不行，修改DNS,到/etc/resolv.conf下添加一下：
nameserver 8.8.8.8
search localdomain
然后重启network服务：service network restart