When you execute the yum command, you will be prompted

Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Could not get metalink https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=x86_64 error was
14: problem making ssl connection

The solution is to comment out mirrorlist from the [epel] node in the /etc/yum.repos.d/epel.repo file, and baseurl to remove the comment,enable. code>enable with a value of 1

command:

Open the /etc/yum.repos.d/epel.repo file with the vim editor

vim /etc/yum.repos.d/epel.repo

Will

[epel]
name=Extra Packages for Enterprise Linux 6 - $basearch
# baseurl Remove the # sign before
baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch
# mirrorlist 前加#好
#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch
failovermethod=priority
# enable change to 1
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6

After modifying the EPEL. Repo file, try the Yum command again, such as:

yum list php