wget http://www.haoxm.net/tools/yum_forAS4.tar.gz
tar xfz yum_forAS4.tar.gz 
cd yum_forAS4
rpm -ivh *.rpm
#如果以安装失败，可 以尝试 rpm -Uvh *.rpm
mv /etc/yum.repos.d/* /tmp/
cp CentOS-Base.repo /etc/yum.repos.d/
rpm --import http://www.haoxm.net/tools/RPM-GPG-KEY-CentOS-4