Cisco Certified Network Professional CCNP Security SIMOS Study Guide

Chapter 1: Secure Communications Architectures
Technology Overview One of the important aspects of network security is providing Confidentiality, Integrity, and Availability of data in motion such as an end-user accessing an organization’s resources from home or café over the public internet. If this data session is clear text in nature, anyone with little technical skill can sniff critical data worth millions of dollars. An attacker can also modify the data if financial gain is not what they want. By the term public internet, it means any kind of network, which is not controlled by the organization. For example, some other autonomous system or group of devices being administered by some other organization or even network administrator, private network like MPLS provider or even some leased line network like Frame Relay.
Similarly, when a small business organization has multiple offices and they cannot afford leased lines connecting to remote offices, they cannot risk sending their critical data off to public internet without any kind of encryption. Virtual Private Network (VPN) comes in to play in such situations where a networking staff wants to implement confidentiality, integrity of mobile data off to public internet, or some other autonomous system with minimum expenses.