White / Grey Listing

White listing is a security practice that involves creating a list of trusted entities, such as IP addresses or applications, that are explicitly permitted to access a network or system while blocking everything else by default. In contrast, grey listing is a temporary restriction method that rejects requests from unknown or suspicious sources, forcing them to retry before gaining access to ensure they are legitimate. Together, these techniques help filter traffic, reduce the attack surface, and prevent unauthorized connections from reaching sensitive infrastructure.