因Redhat 的（yum）更新包只对注册的用户生效，
所以除了配置本地yum源，配置CentOS 7的yum源亦可正常使用yum
下面开始配置CentOS 7 yum源
以下操作本人已实机操作成功。
注意:系统版本一定要相同。
系统：RedHat Enterprise Linux 7.0-x86_64
[root@RHEL7-anker ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.0 (Maipo)
操作步骤如下：
1.首先查看redhat 7.0系统本身所安装的哪些yum 软件包：
rpm -qa | grep yum #列出所有已安装的yum包
2.删除这些包：
命令：rpm -qa | grep yum |xargs rpm -e --nodeps #删除所有以前的yum包
命令执行结束后再次执行：rpm -qa | grep yum
没有结果即为删除成功
3.下载相关安装包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-3.4.3-161.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-1.1.31-50.el7.noarch.rpm
4.安装下载的安装包
[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：最后两个rpm要一起安装，不能单个安装,注意后面加上--nodeps参数，不加的话会有依赖问题
5.centos7.0的系统
[root@CentOS7 ~]# cat /etc/redhat-release
CentOS Linux release 7.3.1611 (Core)
将centos7.0的系统中的yum源文件 /etc/yum.repos.d/CentOS-Base.repo复制到当前操作系统RedHat Enterprise Linux 7.0-x86_64 的 /etc/yum.repos.d/目录下
6.将centos7.0的系统中的/etc/pki/rpm-gpg/*文件复制到当前操作系统RedHat Enterprise Linux 7.0-x86_64 的/etc/pki/rpm-gpg/目录下
7.将复制过来的Centos-Base.repo中的$releasever改为Centos的版本号即可
执行命令：sed -i 's#$releasever#7#g' CentOS-Base.repo
cat CentOS-Base.repo
结果如下
# 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，红色的是修改后的，原为$releasever,改成的7为版本号.
8.将修改后的Centos-Base.repo文件复制到/etc/yum.repos.d/目录下.
9. yum clean all 清除原有缓存
[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 获取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就可以在线安装软件了。
测试一下是否能安装：
[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。
