1.放置iso文件，并挂载iso文件，永久挂载，修改/etc/fstab
参考：https://blog.csdn.net/qq_36119192/article/details/82222175#%E4%B8%80%EF%BC%9A%E9%85%8D%E7%BD%AE%E6%9C%AC%E5%9C%B0yum%E6%BA%90
或者搜索：Linux配置yum源(本地源和网络源) - 谢公子的博客

2.到该目录/etc/yum.repos.d删除所有文件rm -rf *，并创建base.repo

[bash]               
name=my new repo     
baseurl=file:///Archive/RedHat-Enterprise-Linux/7.4   
enabled=1            
gpgcheck=0

解读如下

[name]               #括号中的名称为仓库源名称，要对应上，通常为字母和数字，必须填写
name=my new repo     #对yum的描述，可写可不写
baseurl=file:///mnt/cdrom    #baseurl表示声明yum可以管理并使用的rpm包路径,必须填写
enabled=1            #enabled表示当前仓库是否开启，1为开启，0为关闭，此项不写默认为开启
gpgcheck=0           #gpgcheck表示安装rpm包时，是否基于公私钥对匹配包的安全信息，1表示开启，
                     #0表示关闭，此项不写默认为验证

下面每一步都要做
3.清空

[root@localhost yum.repos.d]# yum clean all
Loaded plugins: product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
Cleaning repos: base
Cleaning up everything
Maybe you want: rm -rf /var/cache/yum, to also free up space taken by orphaned data from disabled or removed repos

4.查看一下repolist

[root@localhost yum.repos.d]# yum repolist
Loaded plugins: product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
base                                            | 4.1 kB     00:00     
(1/2): base/group_gz                              | 137 kB   00:00     
(2/2): base/primary_db                            | 4.0 MB   00:00     
repo id                           repo name                      status
base                              Base                           4,986
repolist: 4,986

5.yum包存储到本地

[root@localhost yum.repos.d]# yum makecache
Loaded plugins: product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
base                                            | 4.1 kB     00:00     
Metadata Cache Created

6.列出yum包

[root@localhost yum.repos.d]# yum list |wc -l
5096