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Use Virtual Private Networks for Secure Internet Data Transfer

Data sent across the public Internet is generally not protected from prying eyes, but you can make your Internet communications secure and extend your private network with a virtual private network (VPN) connection. A VPN connection uses encryption and tunneling to transfer data securely on the Internet to a remote access VPN server on your workplace network.

There are two main types of VPNs:

bulletUser-to-Network
This type of VPN allows a client to use a VPN to connect to a secure network, such as a corporate intranet.
bulletNetwork-to-Network
This type of VPN connects two networks via a VPN connection. This effectively combines two disparate networks into one, eliminating the need for a Wide Area Network (WAN).

In this article I will explain the basics of VPNs and show you how to set up one yourself using Windows 2003 Server and Windows XP Professional.

Tunneling and VPN Protocols

In a VPN, two computers communicate through a VPN tunnel. Tunneling is the process of encapsulating packets within other packets to protect their integrity and privacy during transit. A tunnel performs such tasks as encryption, authentication, packet forwarding, and masking of IP private addresses. Think of a tunnel as a private link between the two computers; whatever one sends to the other is only visible to the other, even though it is sent through a public network like the Internet.

If you're curious about what goes on under the hood of a VPN, there are three protocols you need to know about -- PPTP, L2TP, and IPSec.

Point-to-Point Tunneling Protocol (PPTP)

This was designed by Microsoft (and other companies) to create a secure tunnel between two computers. PPTP provides authentication and encryption services and encapsulates PPP packets within IP packets. It supports multiple Microsoft networking protocols such as LAN-to-LAN and dialup connections. However, it is proprietary and the encryption is weak.

Layer 2 Tunneling Protocol (L2TP)

This works like PPTP, except that it does not include encryption. L2TP was proposed by Cisco Systems and like PPTP, L2TP supports multiple networking protocols.

IPSec

This protocol addresses the shortcomings of L2TP by providing encryption and authentication of IP packets. As such, L2TP is often used together with IPSec to provide a secure connection.

PPTP and L2TP are among the most likely proposals as the basis for a new Internet Engineering Task Force (IETF) standard.

How to make a VPN connection on Windows XP

  1. Open Network Connections. (Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.)
     
  2. Under Network Tasks, click Create a new connection, and then click Next.
     
  3. On the Welcome to the New Connection Wizard page of the New Connection Wizard, click Next.
     
  4. On the Network Connection Type page, click Connect to the network at my workplace, and then click Next as shown below.
     

    Connect to the network at my workplace


     

  5. On the Network Connection page, click Virtual Private Network connection, and then click Next as shown below.

    Virtual Private Network connection


     

  6. On the Connection Name page, type the name of the connection or your company name, and then click Next. An example is shown below.

    Type the name of the connection or your company name


     

  7. If you are using a dial-up connection to an ISP to connect to the Internet, the Public Network page is displayed. In Automatically dial this initial connection, select the name of the connection used to dial your ISP, and then click Next. An example is shown below.

    Select the name of the connection


     

  8. On the VPN Server Selection page, type the Domain Name System (DNS) name or Internet Protocol (IP) address of your company's VPN server on the Internet, and then click Next. An example is shown below.

    Type the Domain Name System (DNS) name or Internet Protocol (IP) address of your company's VPN server


     

  9. On the Completing the New Connection Wizard page, click Finish.
     
  10. A Connect dialog box is displayed. Type the user name and password to access your company's private network and then click Connect. An example is shown below.

    Type the user name and password

     

    IPSec and PPTP Pass Through

    Most routers support a feature known as "IPSec and PPTP pass through." You may need to enable that feature on your router; check its documentation for details.

    IPSec and PPTP are security protocols that provide authentication and encryption over the Internet. The "pass through" feature of the router allows secure packets to flow through the router but the router itself does not perform any authentication or encryption operation.

    IPSec works in two modes -- transport mode and tunnel mode. Transport mode secures IP packets from source-to-destination, whereas tunnel mode puts an IP packet into another packet that is sent to the tunnel's endpoint. Only tunnel mode (ESP) IPSec can be passed through.

    

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Last modified: 01/07/10.