org
https://www.redhat.com/
https://www.centos.org/
https://linux.oracle.com
https://edelivery.oracle.com/osdc/faces/Home.jspx
https://www.debian.org/
https://www.ubuntu.com/
mirrors
http://mirrors.sohu.com/
http://mirrors.tuna.tsinghua.edu.cn/
http://mirror.centos.org/