问题如下：
#yum install pam-devel
#This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Setting up Install Process
Nothing to do
如下图：
提示系统没有在redhat上注册。如果使用redhat的yum源需注册付费，费时费力，因此试图寻找一种不需要注册可以使用的方法，需要重新配置yum源。下面是结合网上的相关资料，搜索的比较可行的解决办法，重新配置yum源。
相关资料参考：http://www.th7.cn/system/lin/201402/50472.shtml?WebShieldDRSessionVerify=YRZRMD7cuYnRVnCdm6Me
实验操作系统：RedHat Enterprise Linux 6.4-x86_64 md5:467B53791903F9A0C477CBB1B24FFD1F
下载地址：http://pan.baidu.com/s/1bniVAMj
第一步下载相关安装包
可以通过http://mirrors.163.com/centos下载，也可以参考下载好的网盘链接：http://pan.baidu.com/s/1qW0MbgC
第二步卸载Redhat自带的yum
#rpm -qa | grep yum | xargs rpm -e --nodeps
第三步安装下载的安装包
#rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm
#rpm -ivh yum-metadata-parser-1.1.2-16.el6.x86_64.rpm
#rpm -ivh yum-3.2.29-40.el6.centos.noarch.rpm yum-plugin-fastestmirror-1.1.30-14.el6.noarch.rpm
第四步到http://mirrors.163.com的 centos帮助文档
中下载CentOS6-Base-163.repo文件，存放到/etc/yum.repo.d中
#wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
第五步将Centos6-Base-163.repo中的$releasever改为Centos的版本号即可
为了防止错误，也可使用我已修改好的文件http://pan.baidu.com/s/1o6AZ23o
文件修改成如下即可：
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client. You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
[base]
name=CentOS-6 - Base - 163.com
baseurl=http://mirrors.163.com/centos/6/os/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=os
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#released updates
[updates]
name=CentOS-6 - Updates - 163.com
baseurl=http://mirrors.163.com/centos/6/updates/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=updates
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#additional packages that may be useful
[extras]
name=CentOS-6 - Extras - 163.com
baseurl=http://mirrors.163.com/centos/6/extras/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=extras
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-6 - Plus - 163.com
baseurl=http://mirrors.163.com/centos/6/centosplus/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#contrib - packages by Centos Users
[contrib]
name=CentOS-6 - Contrib - 163.com
baseurl=http://mirrors.163.com/centos/6/contrib/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=contrib
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
第六步 yum clean all 清除原有缓存
第七步 yum makecache 获取yum列表
等待，大约三分钟后出现下面提示，表示yum更改完成：
Metadata Cache Created
