A VPN connection is a connection that is established using the Internet as the communication infrastructure for the connection, as opposed to a dial-up connection. VPNs allow the Internet to be used as a secure channel for communication with corporate networks.
One of the advantages provided by VPN connections is that they can greatly reduce a company's long distance phone bills while still providing secure remote communications. If the client computer's connection to the Internet is made using a broadband connection, the bandwidth available to the connection can make it many times faster than a dial-up connection. In addition, if a broadband connection is used, the user can remain connected for long periods of time without the worry of being disconnected, as is often the case with dial-in connections.
VPN connections are secured by encrypting data before sending it out over the Internet. The receiving computer on the other end of the connection decrypts the data back into its original format. Microsoft Windows XP Professional supports two different WAN protocols that can be used when creating a VPN connection.
The older protocol is the PPTP (Point-to-Point Tunneling Protocol). PPTP uses PPP-encrypted communications to establish VPN connections. Alternatively, the L2TP (Layer-2 Tunneling Protocol) can be used.
By default, this protocol does not encrypt data. However, it can be configured to use IPSec (Internet Protocol Security), which provides stronger security for VPN connections than PPTP.
Warning! Windows XP Professional can only support a single incoming connection. If a dial-up connection has already been set up on the computer, the connection must also be used to double as a VPN connection.
Setting Up VPN Server On Windows XP:
Windows XP Professional has the ability to act as a VPN server (in addition to providing a client VPN connection to a VNP server) that can support a single incoming VPN connection. While not generally appropriate for the corporate settings, this capability may be of interest to smaller companies or home networks.
The following procedure outlines the steps involved in setting up Windows XP Professional to act as a VPN server using an existing incoming connection.
Click on Start, right-click on My Network Places, and select Properties to open the Network Connections folder.
Right-click on the Incoming Connection and select Properties. The Incoming Connections Properties dialog appears, as shown in the screenshot below.
Configuring an incoming connection to accept a VPN connection
Select the Allow others to make private connections to my computer by tunneling through the Internet or other network option in the Virtual private network section.
Click on OK.