Perimeter security defenses are still valuable, but they used to be enough. The firewall model of network security is based on the castle paradigm. Instead of dumping the notion of a perimeter, we need a new paradigm. In a city there are all sorts of perimeters: fences, buildings, rooms. People move in and out of those perimeters, depending on who they are. I think the usability of products is the most critical Internet security problem right now, and I dont see much relief.”]
Source: https://www.csoonline.com/article/2117688/security-solutions.html