Yum failed (this system isn't registered with RHN.) to resolve

Prompt for the use of the Redhat system on-line installation prompts this system isn't registered with RHN as follows: [root@localhost chenqi]# yum Install httpd
Loaded Plugins:rhnplugin, security
This system is not registered with RHN.
RHN support would be disabled.
Setting up Install Process
No Package httpd available.
Nothing todo
Solution: first of all, I'm using redhat5.0, different versions may be different and need to be adjusted properly.

Step one: Uninstall the Redhat yum components

[Root@localhost chenqi]# rpm-qa|grep Yum|xargs rpm-e--nodeps

Step Two: Install the CentOS Yum package (install in turn)

[Root@localhost chenqi]# wget http://mirrors.ustc.edu.cn/centos/5/os/i386/CentOS/yum-3.2.22-39.el5.centos.noarch.rpm

[Root@localhost chenqi]# wget http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/ yum-metadata-parser-1.1.2-3.el5.centos.i386.rpm

[Root@localhost chenqi]# wget http://mirror.centos.org/centos-5/5/os/i386/CentOS/python-iniparse-0.2.3-4.el5.noarch.rpm

[Root@localhost chenqi]# wget http://mirrors.ustc.edu.cn/centos/5/os/i386/CentOS/ yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm

Step three: Install the RPM package
Installation order

[Root@localhost chenqi]# RPM-IVH python-iniparse-0.2.3-4.el5.noarch.rpm

[Root@localhost chenqi]# RPM-IVH yum-metadata-parser-1.1.2-3.el5.centos.i386.rpm.4

[Root@localhost chenqi]# RPM-IVH yum-3.2.22-39.el5.centos.noarch.rpm.4 Yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm.3

Note: In this place the third step must be installed together, or the following error may occur:

Error One: Warning:yum-3.2.19-18.el5.centos.noarch.rpm:header V3 DSA signature:nokey, key ID e8562897
error:failed dependencies:
Yum-fastestmirror is needed by Yum-3.2.19-18.el5.centos.noarch

Error two: Warning:yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm:header V3 DSA signature:nokey, key ID e8562897
error:failed dependencies:
Yum >= 3.0 is needed by Yum-fastestmirror-1.1.16-13.el5.centos.noarch

Step four: Download the update source and store it in the system directory
[Root@localhost chenqi]# wget Http://docs.linuxtone.org/soft/lemp/CentOS-Base.repo

[Root@localhost chenqi]# MV Centos_base.repo/etc/yum.repos.d/centos-base.repo

so far yum the installation was successful .