redhat 的更新包只對註冊的使用者生效，所以我們自己手動更改成CentOS 的更新包，CentOS幾乎和redhat是一樣的，所以無需擔心軟體包是否可安裝，安裝之後是否有問題，另外CentOS公司去年已經被Redhat 收購了，不說費話了，我們還是來操作吧！
1、首先檢視redhat 7.3系統本身所安裝的那些yum 軟體包：

[[email protected]]$ rpm -qa | grep yum
PackageKit-yum-1.0.7-6.el7.x86_64
yum-3.4.3-150.el7.noarch
yum-metadata-parser-1.1.4-10.
 
el7.x86_64
yum-rhn-plugin-2.0.1-6.el7.noarch
yum-langpacks-0.4.2-7.el7.noarch
yum-utils-1.1.31-40.el7.noarch

注意許可權！！
刪除yum包

[root@localhost]# rpm -e PackageKit-yum-1.0.7-6.el7.x86_64 --nodeps
[root@localhost]# rpm -e yum-3.4.3-150.el7.noarch --nodeps
[root@localhost]# rpm -e yum-metadata-parser-1.1.4-10.el7.x86_64 --nodeps
 

[root@localhost]# rpm -e yum-rhn-plugin-2.0.1-6.el7.noarch --nodeps
[root@localhost]# rpm -e yum-langpacks-0.4.2-7.el7.noarch --nodeps

右上角選擇上網，保證可以聯網，火狐+百度的測試

網易163網路源地址：http://mirrors.163.com/
這裡尋找你要的包，
1，選centos
2，選擇系統版本7.3.1611/
3，選擇包型別（系統） os/
4，系統位數 x86_64/
5，包 Packages/
6，ctrl+f 搜尋yum
7，一般需要如下的幾個包
yum-plugin-fastestmirror
yum-updateonboot
yum-utils
yum-metadata-parser
yum-3.4.3-150.el7

[root@localhost]# wget http://mirrors.163.com/centos/7.3.1611/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-40.el7.noarch.rpm
[root@localhost]#wget http://mirrors.163.com/centos/7.3.1611/os/x86_64/Packages/yum-updateonboot-1.1.31-40.el7.noarch.rpm
[root@localhost]#wget http://mirrors.163.com/centos/7.3.1611/os/x86_64/Packages/yum-utils-1.1.31-40.el7.noarch.rpm
[root@localhost]#wget http://mirrors.163.com/centos/7.3.1611/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
[root@localhost]#wget http://mirrors.163.com/centos/7.3.1611/os/x86_64/Packages/yum-3.4.3-150.el7.centos.noarch.rpm

安裝

[root@localhost]# rpm -ivh yum-*
警告：yum-3.4.3-150.el7.centos.noarch.rpm: 頭V3 RSA/SHA256 Signature, 金鑰 ID f4a80eb5: NOKEY
準備中...                          ################################# [100%]
正在升級/安裝...
   1:yum-metadata-parser-1.1.4-10.el7 ################################# [ 20%]
   2:yum-plugin-fastestmirror-1.1.31-4################################# [ 40%]
   3:yum-3.4.3-150.el7.centos         ################################# [ 60%]
   4:yum-updateonboot-1.1.31-40.el7   ################################# [ 80%]
   5:yum-utils-1.1.31-40.el7          ################################# [100%]

配置
[[email protected] ~]# vim /etc/yum.repos.d/CentOS-Base.repo
將版本號那裡改為你之前選擇的那個版本

[base]
name=CentOS-$releasever -Base
baseurl=http://mirrors.163.com/centos/7.3.1611/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/7.3.1611/os/x86_64/RPM-GPG-KEY-CentOS-7

#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=http://mirrors.163.com/centos/7.3.1611/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/7.3.1611/os/x86_64/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-$releasever - Extras
baseurl=http://mirrors.163.com/centos/7.3.1611/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/7.3.1611/os/x86_64/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=http://mirrors.163.com/centos/7.3.1611/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.163.com/centos/7.3.1611/os/x86_64/RPM-GPG-KEY-CentOS-7

清理之前源，保證只有一個配置檔案

[root@localhost]# yum clean all
[root@localhost]# ls /etc/yum.repos.d/
CentOS-Base.repo

安裝你需要的軟體測試是否正常使用