centos yum无法使用怎么解决

[root@001 ~]#yum -y install gcc gcc-c++ kernel-devel
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
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>

ping www.baidu.com

cd /etc/yum.repos.d
 
mv CentOS-Base.repo CentOS-Base.repo.backup
 
wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
 
mv CentOS6-Base-163.repo CentOS-Base.repo
 
yum clean all