yum This system is not registered with RHN. RHN support will be disabled

新安装的red hat 系统，想使用yum安装一些服务时报错：
Loading "rhnplugin" plugin
Loading "installonlyn" plugin
This system is not registered with RHN.
RHN support will be disabled.
Setting up Install Process
Setting up repositories
No Repositories Available to Set Up
Reading repository metadata in from local files
Parsing package install arguments
Setting up repositories
No Repositories Available to Set Up
Reading repository metadata in from local files
No Match for argument: ssl
Nothing to do
（说什么这个系统没有注册）

如果你系统有wget这个工具，还有网络可以到互联网那就很好解决了。

[root@localhost pake]# cd /etc/yum.repos.d/
[root@localhost yum.repos.d]# ls
rhel-debuginfo.repo
[root@localhost yum.repos.d]# wget
http://docs.linuxtone.org/soft/lemp/CentOS-Base.repo
把red hat的数据包备份起来，使用centos的。
[root@localhost yum.repos.d]# mv rhel-debuginfo.repo rhel-debuginfo.repo.bak

尝试安装成功：
root@localhost yum.repos.d]# yum install ssl
Loading "rhnplugin" plugin
Loading "installonlyn" plugin
This system is not registered with RHN.
RHN support will be disabled.
Setting up Install Process
Setting up repositories
update 100% |=========================| 1.9 kB 00:00
base 100% |=========================| 1.1 kB 00:00
addons 100% |=========================| 1.9 kB 00:00
extras 100% |=========================| 2.1 kB 00:00
Reading repository metadata in from local files
primary.xml.gz 100% |=========================| 386 kB 00:01