1、打开 /etc/yum.repos.d/epel.repo；
/etc/yum.repos.d/epel.repo
2、注释掉mirrorlist，取消注释baseurl；
将
[epel]
name=Extra Packages for Enterprise Linux 7 - $basearch
#baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch
修改为
[epel]
name=Extra Packages for Enterprise Linux 7 - $basearch
baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch
#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch
3、再次使用yum命令即正常！
yum clean all
yum makecache
yum update
yum install -y lsof