1、报错现象如下：
[[email protected] ~]# yum install httpd
已加载插件：langpacks, product-id, search-disabled-repos, subscription-
: manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
There are no enabled repos.
Run "yum repolist all" to see the repos you have.
To enable Red Hat Subscription Management repositories:
subscription-manager repos --enable <repo>
To enable custom repositories:
yum-config-manager --enable <repo>
原因是RHEL是收费的，需要注册才可正常使用。解决办法是用CentOS的yum源替换掉原yum源，CentOS已经被红帽收购，且跟RHEL系统没多大区别，可以免费使用
2、查看Redhat的原yum源
3、进行卸载
4、确定本机可以上网
5、确保http://mirrors.163.com/centos/可以访问，找到自己所需版本进行下载
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-chardet-2.2.1-3.el7_1.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-kitchen-1.1.1-5.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-163.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-1.1.31-52.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-updateonboot-1.1.31-52.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-utils-1.1.31-52.el7.noarch.rpm
如果需要可以拷贝到所需地址：[[email protected] ~]# scp -r /home/software/yum [email protected]:/home/software/
6、安装软件包
[[email protected] yum]# rpm -ivh python-*
[[email protected] yum]# rpm -ivh yum-*
7、新建repo配置文件，如果是其他Relhat版本，将7改为对应的版本数字
[[email protected] yum.repos.d]# vim /etc/yum.repos.d/CenOS-Base.repo
#CentOS-Base.repo
[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
8、清除缓存 [[email protected] ~]# yum clean all
9、验证是否ok [[email protected] ~]# yum install -y httpd
原文地址：https://www.cnblogs.com/zzvb/p/12611510.html