由于RedHat是自带的yum源是收费的，要想使服务器能正常通过yum升级，我们可以直接使用centos的yum源来升级服务器
需要如下包：
m2crypto-0.16-8.el5.i386.rpm
python-elementtree-1.2.6-5.i386.rpm
python-iniparse-0.2.3-4.el5.noarch.rpm
python-sqlite-1.1.7-1.2.1.i386.rpm
python-urlgrabber-3.1.0-6.el5.noarch.rpm
yum-3.2.22-39.el5.centos.noarch.rpm
yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm
yum-metadata-parser-1.1.2-3.el5.centos.i386.rpm
rpm -import http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-5
cd /etc/yum.repos.d/
wget http://mirrors.163.com/.help/CentOS-Base-163.repo
sed -i ‘s/mirrorlist/#mirrorlist/g’ /etc/yum.repos.d/CentOS-Base-163.repo
sed -i ‘s/\/$releasever/\/5/g’ /etc/yum.repos.d/CentOS-Base-163.repo
yum clean metadata
yum makecache