If you enabled the Sucuri firewall and VirtueMart is now responding with errors such as the one below, this step can resolve the issue.
Subject: PayPal IPN Transaction on your site: Possible fraud
Error code 506. Possible fraud. Error with REMOTE IP ADDRESS = 66.xx.xx.78. The remote address of the script posting to this notify script does not match a valid PayPal ip address
This happens because VirtueMart is trying to check if your remote IP address matches the PayPal IP address. However, since your traffic is coming through the Sucuri Firewall, VirtueMart sees the Firewall IP address instead of yours. We always provide the real IP address using multiple standard headers, but some versions of VirtuMart do not support alternate IP headers. To fix this, just add the following code to the top of the notify.php file inside VirtueMart:
if(isset($_SERVER['HTTP_X_SUCURI_CLIENTIP']))
{
$_SERVER[REMOTE_ADDR] = $_SERVER['HTTP_X_SUCURI_CLIENTIP'];
}If you prefer, you can open a ticket in our system and provide us with FTP access to your site so we can implement this for you.