If you are you currently using version less than 4.64 and wish to add the new Additional Security option onto your remote server. Follow these steps.

Step 1 - Updating the files on the remote server

In the CSF Unblocker Admin page, make sure your servers are able to be connected by your WHMCS. You can check this by looking at the Connection Test column (First column on the server listing)

Once you have verified the servers have proper connection, click on the Remote under the Update Remote column

The module will be trigger the remote server to download the latest files from our server in the next cronrun. 

Once the update has completed, click on the Connection Test icon, and you should see the version has been updated to v4.64

Step 2 - Adding the new $allowedIP variable

The final step to complete the upgrade is to to insert the following variable into the remote server's CSFSettings.php file.

$allowedIP array
$allowedIP = array(); //Allow certain IP to access the module. ie only your WHMCS server $allowedIP = array("");

Just fill in the IP of your WHMCS server and the module will now only accept connection from the IP(s) in the array.

Step 3 - Updating the file permission

In v4.64, you can now set the file permission to 700. Simply update the $filePermission variable in CSFSettings.php to 700.

File permission variable
$filePermission = "700";
That's it