因Redhat 的（yum）更新包只對註冊的用戶生效，
所以除了配置本地yum源，配置CentOS 7的yum源亦可正常使用yum
下面開始配置CentOS 7 yum源
以下操作本人已實機操作成功。
注意:系統版本一定要相同。
系統：RedHat Enterprise Linux 7.0-x86_64
[root@RHEL7-anker ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.0 (Maipo)
操作步驟如下：
1.首先查看redhat 7.0系統本身所安裝的哪些yum 軟件包：
rpm -qa | grep yum #列出所有已安裝的yum包
2.刪除這些包：
命令：rpm -qa | grep yum |xargs rpm -e --nodeps #刪除所有以前的yum包
命令執行結束後再次執行：rpm -qa | grep yum
沒有結果即爲刪除成功
3.下載相關安裝包RPM
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-iniparse-0.4-9.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-158.el7.centos.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm
4.安裝下載的安裝包
[root@RHEL7-anker Downloads]#rpm -ivh python-iniparse-0.4-9.el7.noarch.rpm
[root@RHEL7-anker Downloads]#rpm -ivh yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
[root@RHEL7-anker Downloads]#rpm -ivh yum-3.4.3-158.el7.centos.noarch.rpm yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm --nodeps
注：最後兩個rpm要一起安裝，不能單個安裝,注意後面加上--nodeps參數，不加的話會有依賴問題
5.centos7.0的系統
[root@CentOS7 ~]# cat /etc/redhat-release
CentOS Linux release 7.3.1611 (Core)
將centos7.0的系統中的yum源文件 /etc/yum.repos.d/CentOS-Base.repo複製到當前操作系統RedHat Enterprise Linux 7.0-x86_64 的 /etc/yum.repos.d/目錄下
6.將centos7.0的系統中的/etc/pki/rpm-gpg/*文件複製到當前操作系統RedHat Enterprise Linux 7.0-x86_64 的/etc/pki/rpm-gpg/目錄下
7.將複製過來的Centos-Base.repo中的$releasever改爲Centos的版本號即可
執行命令：sed -i 's#$releasever#7#g' CentOS-Base.repo
cat CentOS-Base.repo
結果如下
# 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-7 - Base
#mirrorlist=http://mirrorlist.centos.org/?release=7&arch=$basearch&repo=os
baseurl=http://mirror.centos.org/centos/7/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-7 - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=7&arch=$basearch&repo=updates
baseurl=http://mirror.centos.org/centos/7/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
[extras]
name=CentOS-7 - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=7&arch=$basearch&repo=extras
baseurl=http://mirror.centos.org/centos/7/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing
packages
[centosplus]
name=CentOS-7 - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=7&arch=$basearch&repo=centosplus
baseurl=http://mirror.centos.org/centos/7/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
注意，紅色的是修改後的，原爲$releasever,改成的7爲版本號.
8.將修改後的Centos-Base.repo文件複製到/etc/yum.repos.d/目錄下.
9. yum clean all 清除原有緩存
[root@RHEL7-anker yum.repos.d]# yum clean all
Loaded plugins: fastestmirror, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Cleaning repos: base extras updates
Cleaning up everything
Cleaning up list of fastest mirrors
10. yum makecache 獲取yum列表
[root@RHEL7-anker yum.repos.d]# yum makecache
Loaded plugins: fastestmirror, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
base | 3.6 kB 00:00:00
extras | 3.4 kB 00:00:00
updates | 3.4 kB 00:00:00
(1/12): base/x86_64/group_gz | 155 kB 00:00:00
(2/12): base/x86_64/filelists_db | 6.6 MB 00:00:38
base/x86_64/primary_db FAILED ] 155 kB/s | 11 MB 00:12:21 ETA
http://mirror.centos.org/centos/7/os/x86_64/repodata/bd50ff3d861cc21d254a390a963e9f0fd7b7b96ed9d31ece2f2b1997aa3a056f-primary.sqlite.bz2: [Errno 12] Timeout on http://120.192.95.138:801/cache/mirror.centos.org/centos/7/os/x86_64/repodata/bd50ff3d861cc21d254a390a963e9f0fd7b7b96ed9d31ece2f2b1997aa3a056f-primary.sqlite.bz2?ich_args=e27b6e155c53ff9bc20853c8be611065_1_0_0_5_94fb044d9b84bf033d68857cb366e888353663b5330c20986259f828775ea78f_85f301fcd124012562514a55b9ed13c1_1_0&ich_ip=159-135: (28, 'Operation too slow. Less than 1000 bytes/sec transferred the last 30 seconds')
Trying other mirror.
(3/12): extras/x86_64/prestodelta | 149 kB 00:00:04
(4/12): extras/x86_64/primary_db | 191 kB 00:00:01
(5/12): updates/x86_64/prestodelta | 954 kB 00:00:02
(6/12): extras/x86_64/filelists_db | 1.1 MB 00:00:09
(7/12): extras/x86_64/other_db | 905 kB 00:00:07
(8/12): base/x86_64/other_db | 2.4 MB 00:00:16
(9/12): updates/x86_64/filelists_db | 4.4 MB 00:00:21
(10/12): base/x86_64/primary_db | 5.6 MB 00:00:12
(11/12): updates/x86_64/primary_db | 7.8 MB 00:00:51
updates/x86_64/other_db FAILED ========- ] 81 B/s | 54 MB 247:20:22 ETA
http://mirror.centos.org/centos/7/updates/x86_64/repodata/36288cdc93433b594aed022edabca28fe92c3497e23da598c59f890c0ddd7255-other.sqlite.bz2: [Errno 12] Timeout on http://mirror.centos.org/centos/7/updates/x86_64/repodata/36288cdc93433b594aed022edabca28fe92c3497e23da598c59f890c0ddd7255-other.sqlite.bz2: (28, 'Operation too slow. Less than 1000 bytes/sec transferred the last 30 seconds')
Trying other mirror.
updates/x86_64/other_db FAILED ===================- ] 100 B/s | 80 MB 123:36:37 ETA
http://mirror.centos.org/centos/7/updates/x86_64/repodata/36288cdc93433b594aed022edabca28fe92c3497e23da598c59f890c0ddd7255-other.sqlite.bz2: [Errno 12] Timeout on http://mirror.centos.org/centos/7/updates/x86_64/repodata/36288cdc93433b594aed022edabca28fe92c3497e23da598c59f890c0ddd7255-other.sqlite.bz2: (28, 'Operation too slow. Less than 1000 bytes/sec transferred the last 30 seconds')
Trying other mirror.
(12/12): updates/x86_64/other_db | 93 MB 00:03:40
Determining fastest mirrors
Metadata Cache Created
到此yum就可以在線安裝軟件了。
測試一下是否能安裝：
[root@RHEL7-anker ~]# yum install nmap -y
Loaded plugins: fastestmirror, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package nmap.x86_64 2:6.40-7.el7 will be installed
--> Processing Dependency: nmap-ncat = 2:6.40-7.el7 for package: 2:nmap-6.40-7.el7.x86_64
--> Running transaction check
---> Package nmap-ncat.x86_64 2:6.40-4.el7 will be updated
---> Package nmap-ncat.x86_64 2:6.40-7.el7 will be an update
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
nmap x86_64 2:6.40-7.el7 base 4.0 M
Updating for dependencies:
nmap-ncat x86_64 2:6.40-7.el7 base 201 k
Transaction Summary
================================================================================
Install 1 Package
Upgrade ( 1 Dependent package)
Total download size: 4.2 M
Downloading packages:
No Presto metadata available for base
(1/2): nmap-ncat-6.40-7.el7.x86_64.rpm | 201 kB 00:02
(2/2): nmap-6.40-7.el7.x86_64.rpm | 4.0 MB 00:23
--------------------------------------------------------------------------------
Total 177 kB/s | 4.2 MB 00:24
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Updating : 2:nmap-ncat-6.40-7.el7.x86_64 1/3
Installing : 2:nmap-6.40-7.el7.x86_64 2/3
Cleanup : 2:nmap-ncat-6.40-4.el7.x86_64 3/3
Verifying : 2:nmap-ncat-6.40-7.el7.x86_64 1/3
Verifying : 2:nmap-6.40-7.el7.x86_64 2/3
Verifying : 2:nmap-ncat-6.40-4.el7.x86_64 3/3
Installed:
nmap.x86_64 2:6.40-7.el7
Dependency Updated:
nmap-ncat.x86_64 2:6.40-7.el7
Complete!
看到Complete!，恭喜你修改成功。