4、进入以下网站上面查看软件包的版本是否升级或者找到自己系统所对应的文件包版本更新；
网易163网络源地址：http://mirrors.163.com/
CentOS网络源地址：http://centos.ustc.edu.cn/centos/
5、找到自己所需要的版本下载：
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-150.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-utils-1.1.31-40.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-updateonboot-1.1.31-40.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-40.el7.noarch.rpm
这里出现了一个小问题~~~：安装的python-urlgrabber版本不符合您尝试安装的RPM的依赖关系，我目前没有能力解决这个问题的办法，
后来想了一个折中的办法，FQ去一个国外的yum源网站下载上面这五个较低版本的安装包，在来安装就不会有问题了
在这里附上链接各位可以FQ出去下载对应版本的rpm包
链接：http://rpm.pbone.net/
不报错版本安装包：
yum-3.4.3-132.el7.centos.0.1.noarch.rpm
yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
yum-plugin-fastestmirror-1.1.31-34.el7.noarch.rpm
yum-updateonboot-1.1.31-34.el7.noarch.rpm
yum-utils-1.1.31-34.el7.noarch.rpm
我把这五个rpm包下载到我的Windows电脑里，然后用WinSCP这个软件上传到redhat 7 系统里，WinSCP这个软件的使用方法就不在这里赘述了
9、新建repo 配置文件；
#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 - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=os
baseurl=http://mirrors.163.com/centos/7/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$7 - Updates - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=updates
baseurl=http://mirrors.163.com/centos/7/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
[extras]
name=CentOS-$7 - Extras - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=extras
baseurl=http://mirrors.163.com/centos/7/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$7 - Plus - 163.com
baseurl=http://mirrors.163.com/centos/7/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
10、清除缓存：
11、测试安装是否正常；
Dependencies Resolved
=======================================================================================================================
Package Arch Version Repository Size
=======================================================================================================================
Installing:
lftp x86_64 4.4.8-8.el7_3.2 updates 751 k
Transaction Summary
=======================================================================================================================
Install 1 Package
~~~~~此处省略安装输出内容~~~~
Installed:
lftp.x86_64 0:4.4.8-8.el7_3.2
Complete!
到这里安装完成，以后安装所需包，可以不用本地yum源了，直接使用网络yum源。