1.備份或刪除yum源配置文件
#cd /etc/yum.repos.d
#mv rhel-debuginfo.repo rhel-debuginfo.repo.bak
2.編輯CentOS-Base.repo,填入以下內容
######################
[base]
name=CentOS-5 - Base
repo=os
baseurl=http://centos.ustc.edu.cn/centos/5/os/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[update]
name=CentOS-5 - Updates
baseurl=http://centos.ustc.edu.cn/centos/5/updates/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[addons]
name=CentOS-5 - Addons
baseurl=http://centos.ustc.edu.cn/centos/5/addons/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[extras]
name=CentOS-5 - Extras
baseurl=http://centos.ustc.edu.cn/centos/5/extras/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[centosplus]
name=CentOS-5 - Plus
baseurl=http://centos.ustc.edu.cn/centos/5/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[contrib]
name=CentOS-5 - Contrib
baseurl=http://centos.ustc.edu.cn/centos/5/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
###################
3.從http://centos.ustc.edu.cn/centos/5.4/os/i386/CentOS/下載以下文件並安裝
yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm
yum-3.2.22-20.el5.centos.noarch.rpm
yum-updatesd-0.9-2.el5.noarch.rpm
或者找個FTP站點用wget下載：
#wget ftp://ftp.pdc.kth.se/pub/bambi/centos/5.4/os/i386/CentOS/yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm
#wget ftp://ftp.pdc.kth.se/pub/bambi/centos/5.4/os/i386/CentOS/yum-3.2.22-20.el5.centos.noarch.rpm
#wget ftp://ftp.pdc.kth.se/pub/bambi/centos/5.4/os/i386/CentOS/yum-updatesd-0.9-2.el5.noarch.rpm
#rpm -ivh yum*.rpm
4.如果http://centos.ustc.edu.cn/centos這個服務器的CentOS映像不夠快的話用自己適合的服務器替換，可以用IE上去先看看
5.導入KEY文件，注意大小寫
rpm --import http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
6.測試下
#yum list
#cd /etc/yum.repos.d
#mv rhel-debuginfo.repo rhel-debuginfo.repo.bak
2.編輯CentOS-Base.repo,填入以下內容
######################
[base]
name=CentOS-5 - Base
repo=os
baseurl=http://centos.ustc.edu.cn/centos/5/os/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[update]
name=CentOS-5 - Updates
baseurl=http://centos.ustc.edu.cn/centos/5/updates/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[addons]
name=CentOS-5 - Addons
baseurl=http://centos.ustc.edu.cn/centos/5/addons/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[extras]
name=CentOS-5 - Extras
baseurl=http://centos.ustc.edu.cn/centos/5/extras/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[centosplus]
name=CentOS-5 - Plus
baseurl=http://centos.ustc.edu.cn/centos/5/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[contrib]
name=CentOS-5 - Contrib
baseurl=http://centos.ustc.edu.cn/centos/5/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
###################
3.從http://centos.ustc.edu.cn/centos/5.4/os/i386/CentOS/下載以下文件並安裝
yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm
yum-3.2.22-20.el5.centos.noarch.rpm
yum-updatesd-0.9-2.el5.noarch.rpm
或者找個FTP站點用wget下載：
#wget ftp://ftp.pdc.kth.se/pub/bambi/centos/5.4/os/i386/CentOS/yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm
#wget ftp://ftp.pdc.kth.se/pub/bambi/centos/5.4/os/i386/CentOS/yum-3.2.22-20.el5.centos.noarch.rpm
#wget ftp://ftp.pdc.kth.se/pub/bambi/centos/5.4/os/i386/CentOS/yum-updatesd-0.9-2.el5.noarch.rpm
#rpm -ivh yum*.rpm
4.如果http://centos.ustc.edu.cn/centos這個服務器的CentOS映像不夠快的話用自己適合的服務器替換，可以用IE上去先看看
5.導入KEY文件，注意大小寫
rpm --import http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
6.測試下
#yum list
這方法我在RHEL-5.2 32bit 和RHEL-5.4 64bit都試過了，沒問題！
紅帽6源更新方法參考：http://www.linuxde.net/2011/10/1578.html