1.设置上网代理：https://www.cnblogs.com/jjzd/p/6946215.html
2.使用yum安装软件，提示
This system is not registered with an entitlement server. You can use subscription-manager to register.
修改文件 /etc/yum/pluginconf.d/subscription-manager.conf ,将修改enabled=1为enabled=0
解决方法：https://www.jianshu.com/p/7f22bb72a681
163镜像网址：http://mirrors.163.com/centos/7/os/x86_64/Packages/