"This system is not registered with RHN" solution in Red Hat Linux

The reason is that your Linux is not registered on the Red Hat Network, so you cannot download the software package above. You can use centos as an alternative.
The following describes how to use centos.

1. Uninstall the default Yum package installed by RHEL
View Yum package
Rpm-Qa | grep yum
Detach
Rpm-Qa | grep Yum | xargs rpm-e-nodeps

2. download the new Yum package
Wget http://centos.ustc.edu.cn/centos/5/ OS /i386/CentOS/yum-3.2.22-26.el5.centos.noarch.rpm

Wget http://centos.ustc.edu.cn/centos/5/ OS /i386/CentOS/yum-fastestmirror-1.1.16-14.el5.centos.1.noarch.rpm

Wget http://centos.ustc.edu.cn/centos/5/ OS /i386/CentOS/yum-metadata-parser-1.1.2-3.el5.centos.i386.rpm

And install
Rpm-IVH Yum -*
Note: Yum and Yum-fastestmirror are mutually dependent, so install them at the same time.

3. Download the configuration source of yum
Download the wget http://www.linuxidc.com/files/2011/05/06/CentOS-Base.repo to the/etc/yum. Repos. d/directory

4. Run Yum makecache to generate Cache

Address: http://www.linuxidc.com/Linux/2011-05/35643.htm