Infiltration is a very real problem for network administrators, one that can lead to confidential data being leaked outside of your controlled environment. Every day, new attacks are developed that try to breach a network’s security perimeter. Building a secure network requires that a number of key software and hardware components are implemented and configured correctly. But securing a network is not just about acquiring the right network hardware to block unwanted traffic. What is more important is understanding how a network works, how Internet traffic is managed, how information flows within that network, and what services need to be secured that control the traffic. One cannot fully secure what one does not understand.