一、RedHat的yum配置
1.确保RHEL5中已经安装了yum
[root@lvs-master ~]# rpm -qa |grep yum
yum-metadata-parser-1.1.2-3.el5
yum-updatesd-0.9-2.el5
yum-3.2.22-26.el5
yum-security-1.1.16-13.el5
yum-rhn-plugin-0.5.4-15.el5
2.修改源配置文件 ＃vim /etc/yum.repos.d/CentOS-Base.repo
[base]
name=CentOS-5-Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever5&arch=$basearch&repo=os
#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
baseurl=http://ftp.sjtu.edu.cn/centos/5/os/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
#released updates
[update]
name=CentOS-5-Updates
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=updates
baseurl=http://ftp.sjtu.edu.cn/centos/5/updates/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
#packages used/produced in the build but not released
[addons]
name=CentOS-5-Addons
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=addons
baseurl=http://ftp.sjtu.edu.cn/centos/5/addons/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
#additional packages that may be useful
[extras]
name=CentOS-5-Extras
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=extras
baseurl=http://ftp.sjtu.edu.cn/centos/5/extras/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-5-Plus
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=centosplus
baseurl=http://ftp.sjtu.edu.cn/centos/5/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
#contrib - packages by Centos Users
[contrib]
name=CentOS-5-Contrib
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=contrib
baseurl=http://ftp.sjtu.edu.cn/centos/5/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
# vi dag.repo
[dag]
name=Dag RPM Repository for RHEL5
baseurl=http://ftp.riken.jp/Linux/dag/redhat/el5/en/$basearch/dag/
enabled=1
gpgcheck=1
gpgkey=http://ftp.riken.jp/Linux/dag/packages/RPM-GPG-KEY.dag.txt
3. 导入key
＃rpm --import http://ftp.sjtu.edu.cn/centos/5/os/i386/RPM-GPG-KEY-CentOS-5
4. 运行，测试
＃yum update
5.#yum clean all
方法二：
# cd /etc/yum.repos.d/
#mv CentOS-Base.repo CentOS-Base.repo.bak
#wget http://docs.linuxtone.org/soft/lemp/CentOS-Base.repo
该文件内容如下：
[base]
name=CentOS-5 - Base
baseurl=http://centos.ustc.edu.cn/centos/5/os/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#released updates
[update]
name=CentOS-5 - Updates
baseurl=http://centos.ustc.edu.cn/centos/5/updates/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#packages used/produced in the build but not released
[addons]
name=CentOS-5 - Addons
baseurl=http://centos.ustc.edu.cn/centos/5/addons/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#additional packages that may be useful
[extras]
name=CentOS-5 - Extras
baseurl=http://centos.ustc.edu.cn/centos/5/extras/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-5 - Plus
baseurl=http://centos.ustc.edu.cn/centos/5/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#contrib - packages by Centos Users
[contrib]
name=CentOS-5 - Contrib
baseurl=http://centos.ustc.edu.cn/centos/5/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#packages in testing
[testing]
name=CentOS-5 - Testing
baseurl=http://centos.ustc.edu.cn/centos/5/testing/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
二、提示“This system is not registered with RHN” 的解决
1.卸载rhel的默认安装的yum包
查看yum包
rpm -qa|grep yum
卸载之
rpm -qa|grep yum|xargs rpm -e --nodeps
2.下载新的yum包
wget http://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/yum-3.2.22-40.el5.centos.noarch.rpm
wget http://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm
wget http://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/yum-metadata-parser-1.1.2-4.el5.x86_64.rpm
上面3个rpm地址，可能会因为版本号的变动而变更，我们打开地址（http://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/）然后在里面找到对应名称的下载即可。
并且安装之
rpm -ivh yum-*
注意：yum和yum-fastestmirror相互依赖，所以同时安装即可。
3.下载yum的配置源
wget http://docs.linuxtone.org/soft/lemp/CentOS-Base.repo
4.修改配置源
把CentOS-Base.repo里面的url改成网易的yum源 http://mirrors.163.com/centos/5/os/x86_64/CentOS/ （有什么软件包，可以很清楚的看见），赞一下咱们的公司，就不用到国外的网站了，速度蛮快的。
5.全部更新
把修改后的CentOS-Base.repo复制到/etc/yum.repos.d/目录下，并在该目录下执行yum update进行统一更新，完成即可，这下安装软件什么的就比较方便了，不然的话，呵呵，那就有得你忙了。。。Linux软件包的依赖关系那是相当的头痛。