To register with CloudLinux Network you will need to install rhn-setup package, and execut rhnreg_ks
You also need your activation key, that you should have received when your ordered CloudLinux.
To connect your server to CLN, do: rhnreg_ks --activationkey=<activationkey>
You can find information on how to get trial activation key here.
The example bellow will register a system to CLN using the activation key 1-2b48feedf5b5a0e0609ae028d9275c93
# yum install rhn-setup # rhnreg_ks --activationkey=1-2b48feedf5b5a0e0609ae028d9275c93 --force
