Introduction

When you think about the world today, with hackers everywhere, you need something to reassure you that you have a little privacy. The Virtual Private Network (VPN) provides that on a LAN, WAN, and Remote Access scale for many different types of people.

If you think about it, you can have people anywhere in the world using a VPN on a WAN, sending secure messages over a service provider's network in the middle. Also, you could have people working on the road or from home using a VPN to securely connect to the company infrastructure over an Internet Service Provider (ISP). The latest, and possibly best, way is to use a VPN over some wireless device such as a Cisco Aironet Card or other type of wireless device.

All network administrators are focused on securing their network from the outside world. With the implementation of a VPN from a PC to a Cisco piece of equipment (in other words, a Cisco VPN Concentrator) using IPSec, you are able to securely send information to and from both sides of the VPN. This makes for a very secure environment for remote access users to perform work on a WAN. VPNs can be utilized on different levels of the OSI model, depending on what they are being used for at that time.

In the following chapter, you will learn how IPSec works within a VPN to help prevent security breaches on a network. Also, you will understand the different types of VPNs used...