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How Virtual Private Networks Work
by Jeff Tyson

 Introduction to How Virtual Private Networks Work
What Makes A VPN?
Analogy: Each LAN is an Island
VPN Security
› VPN Technologies
Lots More Information

VPN Technologies
Depending on the type of VPN (remote-access or site-to-site), you will need to put in place certain components to build your VPN. These might include:

  • Desktop software client for each remote user
  • Dedicated hardware such as a VPN concentrator or secure PIX firewall
  • Dedicated VPN server for dial-up services
  • NAS (network access server) used by service provider for remote-user VPN access
  • VPN network and policy-management center

Because there is no widely accepted standard for implementing a VPN, many companies have developed turn-key solutions on their own. For example, Cisco offers several VPN solutions including:

  • VPN concentrator - Incorporating the most advanced encryption and authentication techniques available, Cisco VPN concentrators are built specifically for creating a remote-access VPN. They provide high availability, high performance and scalability and include components, called scalable encryption processing (SEP) modules, that enable users to easily increase capacity and throughput. The concentrators are offered in models suitable for everything from small businesses with up to 100 remote-access users to large organizations with up to 10,000 simultaneous remote users.

    Photo courtesy Cisco Systems, Inc.
    The Cisco VPN 3000 Concentrator

  • VPN-optimized router - Cisco's VPN-optimized routers provide scalability, routing, security and QoS (quality of service). Based on the Cisco IOS (Internet Operating System) software, there is a router suitable for every situation, from small-office/home-office (SOHO) access through central-site VPN aggregation, to large-scale enterprise needs.

    Photo courtesy Cisco Systems, Inc.
    The Cisco 1750 Modular Access Router

  • Cisco secure PIX firewall - An amazing piece of technology, the PIX (private Internet exchange) firewall combines dynamic network address translation, proxy server, packet filtration, firewall and VPN capabilities in a single piece of hardware.

    Photo courtesy Cisco Systems, Inc.
    The Cisco PIX Firewall

Instead of using Cisco IOS, this device has a highly streamlined OS that trades the ability to handle a variety of protocols for extreme robustness and performance by focusing on IP.

Lowest Price
1.Linksys EtherFast Cable/DSL Firewall Router 4 Port Switch VPN ENDPOINT $53.90
3.NetGear FVS318 Cable/DSL Prosafe VPN Firewall Internet Gateway Router w/8-Port Switch $97.00
4.SNAPGEAR SME530 2 Port VPN Firewall $329.77
5.Linksys EtherFast Cable/DSL VPN Router w/4-Port Switch $98.21


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Table of Contents:
Introduction to How Virtual Private Networks Work
What Makes A VPN?
Analogy: Each LAN is an Island
VPN Security
› VPN Technologies
Lots More Information

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