With distributed workforces and mobile technologies, the network perimeter has evolved beyond the physical limits of most corporate campuses. The days when the perimeter was an actual boundary are a fond memory. Back then, firewalls did a decent job of protecting the network from outside threats, and intrusion prevention tools protected against insiders. But over time, the bad guys have gotten better: Spear phishing has made it easier to infiltrate malware, and poor password controls have made it easier to exfiltrate data. This means that the insiders are getting harder to detect, and IT assets are getting more distributed and harder to defend.