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Security+ Domain 2.1 - Remote Access Technologies
 
Virtual Private Networks
 
What is a Virtual Private Network?
A virtual private network, or VPN, is a secure way to connect one location, or user, to another over a public network.
 
What are some advantages of VPNs?
VPNs are widely used because:
  • They reduce costs - the company does not have to pay for private circuits (dedicated or for rent) and there are no long-distance fees for dialing in remotely to a Remote Access Service (RAS) server.
  • They increase the security of data passing through a public network

 

How do they work?

VPNs create virtual "tunnels" inside a public network where data is encrypted.  Data packets are encapsulated, or put inside, other packets which are then sent over the network.  There are three protocols necessary for tunneling:

  1. The carrier protocol - the protocol used by the public network, such as IP over the Internet
  2. The encapsulation protocol - the protocol determing how the data is wrapped.  There are several possibilities including the Point-to-point tunneling protocol (PPTP), Site-two tunneling protocol (L2TP), Secure Shell (SSH), and IPSec.
  3. The passenger protocol - the protocol of the original data.  There are several different protocols including IP, IPX, and NetBEUI.

 

What types of VPNs are there?

There are two types of VPNs:  Site-to-Site and Remote Access

  • Site-to-site, or LAN-to-LAN, VPNs are generally between business partners or different branches/offices of a corporation.  The tunnel is usually created between two routers or firewalls.  This type is sometimes split into intranet VPNs, which are between two offices of the same company and extranet VPNs between two different companies.
  • Remote Access VPNs, or private virtual dial-up networks (PVDNs), are created from an end user to the company.

 

Resources:

TechExams.net - Security+ Technote:  Remote Access Technologies. By: Johan Hiemstra

http://www.techexams.net/technotes/securityplus/ras.shtml

 

Security+ Study Guide & DVD Training System, Second Edition.  By: Ido Dubrawsky, Jeremy Faircloth

ISBN: 1597491535  http://www.syngress.com/catalog/?pid=4350

 

Howstuffworks.com - "How Virtual Private Networks Work."  By:  Jeff Tyson.  http://computer.howstuffworks.com/vpn.htm