在CentOS 6.3 x86_64下安装php-mcrypt的时候出现了问题：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

1. [epel]
2. name=Extra Packages for Enterprise Linux 6 - $basearch
3. #baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch
4. mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch

修改为

1. [epel]
2. name=Extra Packages for Enterprise Linux 6 - $basearch
3. baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch
4. #mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch

再清理源，重新安装

1. yum clean all
2. 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

yum安装时出现：Cannot retrieve metalink for repository: epel. Please verify its path and try again