VPN A virtual private network that is established over, in general, the Internet It is virtual because it exists as a virtual entity within a public network It is private because it is confined to a set of private users
Why is it a Virtual Private Network? From the user’s perspective, it appears as a network consisting of dedicated network links These links appear as if they are reserved for the VPN clientele Because of encryption, the network appears to be private
VPN Major Characteristics Must emulate a point-to-point link –Done by encapsulating the data that would facilitate allow it to travel the Internet to reach the end point Must emulate a private link –Done by encrypting the data in the data packets
Tunnel and Connections Tunnel –The portion of the network where the data is encapsulated Connection –The portion of the network where the data is encrypted
Application Areas In general, provide users with connection to the corporate network regardless of their location The alternative of using truly dedicated lines for a private network are expensive propositions
Some Common Uses of VPN Provide users with secured remote access over the Internet to corporate resources Connect two computer networks securely over the Internet –Example: Connect a branch office network to the network in the head office Secure part of a corporate network for security and confidentiality purpose
More on Tunneling Tunneling involves the encapsulation, transmission and decapsulation of data packets The data is encapsulated with additional headers The additional headers provide routing information for encapsulated data to be routed between the end points of a tunnel
Tunnel Types Voluntary –VPN request is initiated by the client –The client remains the end point Compulsory –VPN access server creates a compulsory tunnel for the client –In this case, the dial-up access server between the user’s computer and the tunnel server is the tunnel end point that acts as a client
The Choice Voluntary tunneling is used in most applications
Other Important Protocols in VPN Microsoft Point-to-Point Encryption (MPPE) Extensible Authentication Protocol (EAP) Remote Authentication Dial-in User Service (RADIUS)
Component Details A computer running Windows Server 2003, Enterprise Edition, named DC1 that is acting as a domain controller, a Domain Name System (DNS) server, a Dynamic Host Configuration Protocol (DHCP) server, and a certification authority (CA). A computer running Windows Server 2003, Standard Edition, named VPN1 that is acting as a VPN server. VPN1 has two network adapters installed. A computer running Windows Server 2003, Standard Edition, named IAS1 that is acting as a Remote Authentication Dial-in User Service (RADIUS) server.
Component Details Cont. A computer running Windows Server 2003, Standard Edition, named IIS1 that is acting as a Web and file server. A computer running Windows XP Professional named CLIENT1 that is acting as a VPN client.
Private and Public Networks Private –172.16.0.0/24 Simulated Public –10.0.0.0/24
DC1 DC1 is a computer running Windows Server 2003, Enterprise Edition that is providing the following services: –A domain controller for the example.com Active Directory domain –.A DNS server for the example.com DNS domain. –A DHCP server for the intranet network segment –The enterprise root certification authority (CA) for the example.com domain.
Step 1: Configuring DC1 The first step is to configure the following –Active Directory –DNS –DHCP –CA
Step 2: Configure IAS1 Install Windows Server –Provides RADIUS authentication, authorization, and accounting for VPN1 Register server in active directory Configure new remote access policies Specify authentication method and encryption level
Step 3: Configure IIS1 Configure this as a web server for web access as well as file sharing
Step 4: Configure VPN1 Install VPN1 as a member server in the domain Configure TCP/IP for the Intranet and Internet sides Configure and enable routing and remote access Setup the server to work with a RADIUS server Setup the DHCP relay agent parameters
Step 5: Configure Client1 CLIENT1 is a computer running Windows XP Professional that is acting as a VPN client and gaining remote access to intranet resources across the simulated Internet. To configure CLIENT1 as a VPN client for a PPTP connection, perform the following steps:
1.Connect CLIENT1 to the intranet network segment. 2.On CLIENT1, install Windows XP Professional as a member computer named CLIENT1 of the example.com domain. 3.Add the VPNUser account in the example.com domain to the local Administrators group. 4.Log off and then log on using the VPNUser account in the example.com domain.
5.From Control Panel-Network Connections, obtain properties on the Local Area Network connection, and then obtain properties on the Internet Protocol (TCP/IP). 6.Click the Alternate Configuration tab, and then click User configured. 7.In IP address, type 10.0.0.1. In Subnet mask, type 255.255.255.0. This is shown in the following figure.
8.Click OK to save changes to the Internet Protocol (TCP/IP). Click OK to save changes to the Local Area Network connection. 9.Shut down the CLIENT1 computer. 10.Disconnect the CLIENT1 computer from the intranet network segment, and connect it to the simulated Internet network segment.
11.Restart the CLIENT1 computer and log on using the VPNUser account. 12.On CLIENT1, open the Network Connections folder from Control Panel. 13.In Network Tasks, click Create a new connection. 14.On the Welcome to the New Connection Wizard page of the New Connection Wizard, click Next. 15.On the Network Connection Type page, click Connect to the network at my workplace. This is shown in the following figure.
19.Click Next. On the Connection Availability page, click Next. 20.On the Completing the New Connection Wizard page, click Finish. The Connect PPTPtoCorpnet dialog box is displayed. This is shown in the following figure.
23.Click OK to save changes to the PPTPtoCorpnet connection. The Connect PPTPtoCorpnet dialog box is displayed. 24.In User name, type example/VPNUser. In Password, type the password you chose for the VPNUser account. This is shown in the following figure.
25.Click Connect. 26.When the connection is complete, run Internet Explorer. 27.If prompted by the Internet Connection Wizard, configure it for a LAN connection. In Address, type http://IIS1.example.com/winxp.gif. You should see a Windows XP graphic. 28.Click Start, click Run, type \\IIS1\ROOT, and then click OK. You should see the contents of the Local Drive (C:) on IIS1. 29.Right-click the PPTPtoCorpnet connection, and then click Disconnect.