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