vim /etc/yum.repos.d/CentOS-Base.repo
取消注释mirrorlist=*** --互联网源
注释baseurl=**** --局域网源
CentOS 6
rpm -ivh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm rpm -ivh http://mirrors.kernel.org/fedora-epel/6/i386/epel-release-6-8.noarch.rpm
yum repolist
yum update