From Perimeter to Zero Trust: The Evolution of Cyber Defense What is the Traditional Perimeter Security Model? The traditional perimeter security model, often referred to as the castle-and-moat approach, focuses on securing the network’s outer boundaries. This model employs firewalls and other security measures to block external threats from entering the network. Once inside the network, users are typically granted unrestricted access to resources, creating a false sense of security. This approach assumes that anyone within the network perimeter is