When organizations originally started building network infrastructure, the internet was not a safe place to conduct business. Companies constructed their own private networks and built firewalls that could protect what was inside. These firewalls protected the private network at the office, so that devices sitting inside the same four walls, on the same local network, were considered trusted and allowed to communicate. As employees worked on the go, however, they wanted to connect to internal machines or services on the company’s private network. To do this, they had to use a Virtual Private Network (VPN). This perimeter-defense approach came to be known as the “castle and moat” model: VPNs are the bridges, and firewalls are the locked doors that you need a secret password to open. But with organizations migrating to a cloud-based infrastructure, and with more and more people working remotely, the limitations of the “castle and moat” model have come into sharper focus.