Virtual Private Network (VPN)

Thesis on Virtual Private Networks VPN

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Step-by-Step Guide for Setting Up VPN-based Remote Access in a Test Lab

On This Page

	Introduction
	PPTP-based Remote Access VPN Connections
	L2TP/IPSec-based Remote Access VPN Connections
	EAP-TLS-based Remote Access VPN Connections
	Summary
	Related Links

Introduction

This paper provides detailed information about how you can use five computers to create a test lab with which to configure and test virtual private network (VPN) remote access with Windows XP and the Windows Server 2003 family. These instructions are designed to take you step-by-step through the configuration required for Point-to-Point Protocol (PPTP) and Layer Two Tunneling Protocol with Internet Protocol security (L2TP/IPSec) connections, and finally a VPN connection that uses certificate-based Extensible Authentication Protocol-Transport Level Security (EAP-TLS) authentication.

Note: The following instructions are for configuring a test lab using a minimum number of computers. Individual computers are needed to separate the services provided on the network and to clearly show the desired functionality. This configuration is neither designed to reflect best practices nor is it designed to reflect a desired or recommended configuration for a production network. The configuration, including IP addresses and all other configuration parameters, is designed only to work on a separate test lab network.

PPTP-based Remote Access VPN Connections

The infrastructure for the VPN test lab network consists of five computers performing the following services:

Figure 1 shows the configuration of the VPN test lab.

 

Figure 1: Configuration of the VPN test lab
 

There is a network segment representing a corporate intranet and a network segment representing the Internet. All computers on the corporate intranet are connected to a common hub or Layer 2 switch. All computers on the Internet are connected to a separate common hub or Layer 2 switch. Private addresses are used throughout the test lab configuration. The private network of 172.16.0.0/24 is used for the intranet. The private network of 10.0.0.0/24 is used for the simulated Internet.

IIS1 obtains its IP address configuration using DHCP. CLIENT1 uses DHCP for its IP address configuration, however, it is also configured with an alternate IP configuration so that it can be placed on either the intranet network segment or the simulated Internet. All other computers have a manual IP address configuration. There are no Windows Internet Name Service (WINS) servers present.

The following sections describe the configuration for each of the computers in the test lab to set up the basic infrastructure and to do a PPTP-based remote access connection. PPTP is typically used when there is no public key infrastructure (PKI) to issue computer certificates that are required for L2TP/IPSec connections.

To reconstruct this test lab, configure the computers in the order presented. Additional sections of this paper describe L2TP/IPSec and EAP-TLS-based remote access connections.

DC1

DC1 is a computer running Windows Server 2003, Enterprise Edition that is providing the following services:

Note: Windows Server 2003, Enterprise Edition is used so that autoenrollment of user certificates for EAP-TLS authentication can be configured. This is described in the "EAP-TLS-based VPN Remote Access Connections" section of this paper.

To configure DC1 for these services, perform the following steps.

1.	Install Windows Server 2003, Enterprise Edition, as a stand-alone server.
2.	Configure the TCP/IP protocol with the IP address of 172.16.0.1 and the subnet mask of 255.255.255.0.
3.	Run the Active Directory Installation Wizard (dcpromo.exe) for a new domain named example.com in a new forest. Install the DNS service when prompted.
4.	Using the Active Directory Users and Computers snap-in, right-click the example.com domain, and then click Raise Domain Functional Level.
5.	Click Windows Server 2003, and then click Raise.
6.	Install Dynamic Host Configuration Protocol (DHCP) as a Networking Services component using Control Panel-Add or Remove Programs.
7.	Open the DHCP snap-in from the Administrative Tools folder.
8.	Click Action, and then click Authorize to authorize the DHCP service.
9.	In the console tree, right-click dc1.example.com, and then click New Scope.
10.	On the Welcome page of the New Scope Wizard, click Next.
11.	On the Scope Name page, type CorpNet in Name. This is shown in the following figure.
12.	Click Next. On the IP Address Range page, type 172.16.0.10 in Start IP address, 172.16.0.100 in End IP address, and 24 in Length. This is shown in the following figure.
13.	Click Next. On the Add Exclusions page, click Next.
14.	On the Lease Duration page, click Next.
15.	On the Configure DHCP Options page, click Yes, I want to configure DHCP options now. This is shown in the following figure.
16.	Click Next. On the Router (Default Gateway) page, click Next.
17.	On the Domain Name and DNS Servers page, type example.com in Parent domain. Type 172.16.0.1 in IP address, and then click Add. This is shown in the following figure.
18.	Click Next. On the WINS Servers page, click Next.
19.	On the Activate Scope page, click Yes, I want to activate the scope now. This is shown in the following figure.
20.	Click Next. On the Completing the New Scope Wizard page, click Finish.
21.	Install the Certificate Services component as an enterprise root CA with the name "Example CA" using Control Panel-Add or Remove Programs.
22.	Open the Active Directory Users and Computers snap-in.
23.	In the console tree, open example.com.
24.	Right-click Users, and then click Computer.
25.	In the New Object Computer dialog box, type IAS1 in Computer name. This is shown in the following figure.
26.	Click Next. In the Managed dialog box, click Next. In the New Object Computer dialog box, click Finish.
27.	Use steps 24-26 to create additional computer accounts with the following names: IIS1, VPN1, and CLIENT1.
28.	In the console tree, right-click Users, and then click User.
29.	In the New Object User dialog box, type VPNUser in First name and type VPNUser in User logon name. This is shown in the following figure.
30.	Click Next.
31.	In the New Object User dialog box, type a password of your choice in Password and Confirm password. Clear the User must change password at next logon check box and select the Password never expires check box. This is shown in the following figure.
32.	In the New Object User dialog box, click Finish.
33.	In the console tree, right-click Users, and then click Group.
34.	In the New Object Group dialog box, type VPNUsers in Group name, and then click OK. This is shown in the following figure.
35.	In the details pane, double-click VPNUsers.
36.	Click the Members tab, and then click Add.
37.	In the Select Users, Contacts, Users, or Groups dialog box, type vpnuser in Enter the object names to select. This is shown in the following figure.
38.	Click OK. In the Multiple Names Found dialog box, click OK. The VPNUser user account is added to the VPNUsers group. This is shown in the following figure.
39.	Click OK to save changes to the VPNUsers group.

IAS1

IAS1 is a computer running Windows Server 2003, Standard Edition that is providing RADIUS authentication, authorization, and accounting for VPN1. To configure IAS1 as a RADIUS server, perform the following steps:

1.	Install Windows Server 2003, Standard Edition, as a member server named IAS1 in the example.com domain.
2.	For the intranet local area connection, configure the TCP/IP protocol with the IP address of 172.16.0.2, the subnet mask of 255.255.255.0, and the DNS server IP address of 172.16.0.1.
3.	Install Internet Authentication Service as a Networking Services component in Control Panel-Add or Remove Programs.
4.	Open the Internet Authentication Service snap-in from the Administrative Tools folder.
5.	Right-click Internet Authentication Service, and then click Register Server in Active Directory. When the Register Internet Authentication Service in Active Directory dialog box appears, click OK. This is shown in the following figure.
6.	In the console tree, right-click Clients, and then click New RADIUS Client.
7.	On the Name and Address page of the New RADIUS Client wizard, for Friendly name, type VPN1. In Client address (IP or DNS), type 172.16.0.3. This is shown in the following figure.
8.	Click Next. On the Additional Information page of the New RADIUS Client wizard, for Shared secret, type a shared secret for VPN1, and then type it again in Confirm shared secret. This is shown in the following figure.
9.	Click Finish.
10.	In the console tree, right-click Remote Access Policies, and then click New Remote Access Policy.
11.	On the Welcome to the New Remote Access Policy Wizard page, click Next.
12.	On the Policy Configuration Method page, type VPN remote access to intranet in Policy name. This is shown in the following figure.
13.	Click Next. On the Access Method page, select VPN. This is shown in the following figure.
14.	Click Next. On the User or Group Access page, select Group. This is shown in the following figure.
15.	Click Add. In the Select Groups dialog box, type vpnusers in Enter the object names to select. This is shown in the following figure.
16.	Click OK. The VPNUsers group in the example.com domain is added to the list of groups on the Users or Groups page. This is shown in the following figure.
17.	Click Next. On the Authentication Methods page, the MS-CHAP v2 authentication protocol is selected by default. This is shown in the following figure.
18.	Click Next. On the Policy Encryption Level page, clear the Basic encryption and Strong encryption check boxes. This is shown in the following figure.
19.	Click Next. On the Completing the New Remote Access Policy page, click Finish.

IIS1

IIS1 is a computer running Windows Server 2003, Standard Edition, and Internet Information Services (IIS). It is providing Web and file server services for intranet clients. To configure IIS1 as a Web and file server, perform the following steps:

VPN1

VPN1 is a computer running Windows Server 2003, Standard Edition that is providing VPN server services for Internet-based VPN clients. To configure VPN1 as a VPN server, perform the following steps:

1.	Install Windows Server 2003, Standard Edition, as a member server named VPN1 in the example.com domain.
2.	Open the Network Connections folder.
3.	For the intranet local area connection, rename the connection to "CorpNet." For the Internet local area connection, rename the connection to "Internet." This is shown in the following figure.
4.	Configure the TCP/IP protocol for the CorpNet connection with the IP address of 172.16.0.4, the subnet mask of 255.255.255.0, and the DNS server IP address of 172.16.0.1.
5.	Configure the TCP/IP protocol for the Internet connection with the IP address of 10.0.0.2 and the subnet mask of 255.255.255.0.
6.	Run the Routing and Remote Access snap-in from the Administrative Tools folder.
7.	In the console tree, right-click VPN1 and click Configure and Enable Routing and Remote Access.
8.	On the Welcome to the Routing and Remote Access Server Setup Wizard page, click Next.
9.	On the Configuration page, Remote access (dial-up or VPN) is selected by default. This is shown in the following figure.
10.	Click Next. On the Remote Access page, select VPN. This is shown in the following figure.
11.	Click Next. On the VPN Connection page, click the Internet interface in Network interfaces. This is shown in the following figure.
12.	Click Next. On the IP Address Assignment page, Automatically is selected by default. This is shown in the following figure.
13.	Click Next. On the Managing Multiple Remote Access Servers page, click Yes, set up this server to work with a RADIUS server. This is shown in the following figure.
14.	Click Next. On the RADIUS Server Selection page, type 172.16.0.2 in Primary RADIUS server and the shared secret in Shared secret. This is shown in the following figure.
15.	Click Next. On the Completing the Routing and Remote Access Server Setup Wizard page, click Finish.
16.	You are prompted with a message describing the need to configure the DHCP Relay Agent. This is shown in the following figure.
17.	Click OK.
18.	In the console tree, open VPN1 (local), then IP Routing, and then DHCP Relay Agent. Right click DHCP Relay Agent, and then click Properties.
19.	In the DHCP Relay Agent Properties dialog box, type 172.16.0.1 in Server address. This is shown in the following figure.
20.	Click Add, and then click OK.

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.
16.	Click Next. On the Network Connection page, click Virtual Private Network connection. This is shown in the following figure.
17.	Click Next. On the Connection Name page, type PPTPtoCorpnet in Company Name. This is shown in the following figure.
18.	Click Next. On the VPN Server Selection page, type 10.0.0.2 in Host name or IP address. 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.
21.	Click Properties, and then click the Networking tab.
22.	On the Networking tab, in Type of VPN, click PPTP VPN. 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.

L2TP/IPSec-based Remote Access VPN Connections

L2TP/IPSec-based remote access VPN connections require computer certificates on the VPN client and the VPN server. L2TP/IPSec is typically used when there are stronger requirements for security and a public key infrastructure (PKI) is in place to issue computer certificates to VPN clients and servers.

DC1

To configure DC1 for autoenrollment of computer certificates, perform the following steps.

1.	Open the Active Directory Users and Computers snap-in.
2.	In the console tree, double-click Active Directory Users and Computers, right-click the example.com domain, and then click Properties.
3.	On the Group Policy tab, click Default Domain Policy, and then click Edit.
4.	In the console tree, open Computer Configuration, then Windows Settings, then Security Settings, then Public Key Policies, then Automatic Certificate Request Settings. This is shown in the following figure.
5.	Right-click Automatic Certificate Request Settings, point to New, and then click Automatic Certificate Request.
6.	On the Welcome to the Automatic Certificate Request Setup Wizard page, click Next.
7.	On the Certificate Template page, click Computer. This is shown in the following figure.
8.	Click Next. On the Completing the Automatic Certificate Request Setup Wizard page, click Finish. The Computer certificate type now appears in the details pane of the Group Policy Object Editor snap-in. This is shown in the following figure.
9.	Type gpupdate at a command prompt to update group policy on DC1.

VPN1

To immediately update group policy and request a computer certificate, type gpupdate at a command prompt.

CLIENT1

To obtain a computer certificate on CLIENT1 and then configure an L2TP/IPSec-based remote access VPN connection, perform the following steps:

1.	Shut down CLIENT1.
2.	Disconnect the CLIENT1 computer from the simulated Internet network segment, and connect it to the intranet network segment.
3.	Restart the CLIENT1 computer and log on using the VPNUser account. Computer and user group policy is automatically updated.
4.	Shut down the CLIENT1 computer.
5.	Disconnect the CLIENT1 computer from the intranet network segment, and connect it to the simulated Internet network segment.
6.	Restart the CLIENT1 computer and log on using the VPNUser account.
7.	On CLIENT1, open the Network Connections folder from Control Panel.
8.	In Network Tasks, click Create a new connection.
9.	On the Welcome to the New Connection Wizard page of the New Connection Wizard, click Next.
10.	On the Network Connection Type page, click Connect to the network at my workplace. This is shown in the following figure.
11.	Click Next. On the Network Connection page, click Virtual Private Network connection. This is shown in the following figure.
12.	Click Next. On the Connection Name page, type L2TPtoCorpnet in Company Name. This is shown in the following figure.
13.	Click Next. On the VPN Server Selection page, type 10.0.0.2 in Host name or IP address. This is shown in the following figure.
14.	Click Next. On the Public Network page, click Do not dial the initial connection. This is shown in the following figure.
15.	Click Next. On the Connection Availability page, click Next.
16.	On the Completing the New Connection Wizard page, click Finish. The Connect L2TPtoCorpnet dialog box is displayed. This is shown in the following figure.
17.	Click Properties, and then click the Networking tab.
18.	On the Networking tab, in Type of VPN, click L2TP IPSec VPN. This is shown in the following figure.
19.	Click OK to save changes to the L2TPtoCorpnet connection. The Connect L2TPtoCorpnet dialog box is displayed.
20.	In User name, type example/VPNUser. In Password, type the password you chose for the VPNUser account. This is shown in the following figure.
21.	Click Connect.
22.	When the connection is complete, run the Web browser.
23.	In Address, type http://IIS1.example.com/winxp.gif. You should see a Windows XP graphic.
24.	Click Start, click Run, type \\IIS1\ROOT, and then click OK. You should see the contents of the Local Drive (C:) on IIS1.
25.	Right-click the L2TPtoCorpnet connection, and then click Disconnect.

EAP-TLS-based Remote Access VPN Connections

EAP-TLS-based remote access VPN connections require a user certificate on the VPN client and a computer certificate on the IAS server. EAP-TLS is used when you want to authenticate your VPN connection with the most secure user-level authentication protocol. Locally installed user certificates in the following steps are used to make it easier to set up in a test lab. In a production environment, it is recommended that you use smart cards, rather than locally installed user certificates, for EAP-TLS authentication.

DC1

To configure DC1 for autoenrollment of user certificates, perform the following steps:

1.	Click Start, click Run, type mmc, and then click OK.
2.	On the File menu, click Add/Remove Snap-in, and then click Add.
3.	Under Snap-in, double-click Certificate Templates, click Close, and then click OK.
4.	In the console tree, click Certificate Templates. All of the certificate templates will be displayed in the details pane. This is shown in the following figure.
5.	In the details pane, click the User template.
6.	On the Action menu, click Duplicate Template.
7.	In the Display Name field, type VPNUser.
8.	Ensure that the Publish Certificate in Active Directory check box is selected. This is shown in the following figure.
9.	Click the Security tab.
10.	In the Group or user names field, click Domain Users.
11.	In the Permissions for Domain Users list, select the Enroll and Autoenroll permission check boxes. This is shown in the following figure.
12.	Click OK.
13.	Open the Certification Authority snap-in.
14.	In the console tree, open Certification Authority, then Example CA, then Certificate Templates. This is shown in the following figure.
15.	On the Action menu, point to New, and then click Certificate to Issue.
16.	Click VPNUser. This is shown in the following figure.
17.	Click OK.
18.	Open the Active Directory Users and Computers snap-in.
19.	In the console tree, double-click Active Directory Users and Computers, right-click the example.com domain, and then click Properties.
20.	On the Group Policy tab, click Default Domain Policy, and then click Edit.
21.	In the console tree, open User Configuration, then Windows Settings, then Security Settings, then Public Key Policies. This is shown in the following figure.
22.	In the details pane, double-click Autoenrollment Settings.
23.	Click Enroll certificates automatically. Select the Renew expired certificates, update pending certificates, and remove revoked certificates check box. Select the Update certificates that use certificate templates check box. This is shown in the following figure.
24.	Click OK.

IAS1

To configure IAS1 with a computer certificate and for EAP-TLS authentication, perform the following steps:

1.	To ensure that IAS1 has autoenrolled a computer certificate, type gpupdate at a command prompt.
2.	Open the Internet Authentication Service snap-in.
3.	In the console tree, click Remote Access Policies.
4.	In the details pane, double-click VPN remote access to intranet. The VPN remote access to intranet Properties dialog box is displayed. This is shown in the following figure.
5.	Click Edit Profile, and then click the Authentication tab. This is shown in the following figure.
6.	On the Authentication tab, click EAP Methods. The Select EAP Providers dialog box is displayed. This is shown in the following figure.
7.	Click Add. The Add EAP dialog box is displayed. This is shown in the following figure.
8.	Click Smart Card or other certificate, and then click OK.
9.	Click Edit. The Smart Card or other Certificate Properties dialog box is displayed. This is shown in the following figure.
10.	The properties of the computer certificate issued to the IAS1 computer are displayed. This step verifies that IAS has an acceptable computer certificate installed to perform EAP-TLS authentication. Click OK.
11.	Click OK to save changes to EAP providers. Click OK to save changes to the profile settings.
12.	When prompted to view help topics, click No. Click OK to save changes to the remote access policy.

These configuration changes will allow the VPN remote access to intranet remote access policy to authorize VPN connections using the EAP-TLS authentication method.

CLIENT1

To obtain a user certificate on CLIENT1 and then configure an EAP-TLS-based remote access VPN connection, perform the following steps:

1.	Shut down CLIENT1.
2.	Disconnect the CLIENT1 computer from the simulated Internet network segment, and connect it to the intranet network segment.
3.	Restart the CLIENT1 computer and log on using the VPNUser account. Computer and user group policy is automatically updated.
4.	Shut down the CLIENT1 computer.
5.	Disconnect the CLIENT1 computer from the intranet network segment, and connect it to the simulated Internet network segment.
6.	Restart the CLIENT1 computer and log on using the VPNUser account.
7.	On CLIENT1, open the Network Connections folder from Control Panel.
8.	In Network Tasks, click Create a new connection.
9.	On the Welcome to the New Connection Wizard page of the New Connection Wizard, click Next.
10.	On the Network Connection Type page, click Connect to the network at my workplace.
11.	Click Next. On the Network Connection page, click Virtual Private Network connection.
12.	Click Next. On the Connection Name page, type EAPTLStoCorpnet in Company Name.
13.	Click Next. On the VPN Server Selection page, type 10.0.0.2 in Host name or IP address.
14.	Click Next. On the Public Network page, click Do not dial the initial connection.
15.	Click Next. On the Connection Availability page, click Next.
16.	On the Completing the New Connection Wizard page, click Finish. The Connect EAPTLStoCorpnet dialog box is displayed. This is shown in the following figure.   .
17.	Click Properties, and then click the Security tab.
18.	On the Security tab, click Advanced, and then click Settings. The Advanced Security Settings dialog box is displayed.
19.	On the Advanced Security Settings dialog box, click Use Extensible Authentication Protocol (EAP). This is shown in the following figure.
20.	Click Properties. On the Smart Card or other Certificate Properties dialog box, click Use a certificate on this computer. This is shown in the following figure.
21.	Click OK to save changes to the Smart Card or Other Certificate EAP type. Click OK to save changes to the Advanced Security Settings. Click OK to save changes to the Security tab. The connection is immediately initiated using the installed user certificate.
22.	When the connection is complete, run the Web browser.
23.	In Address, type http://IIS1.example.com/winxp.gif. You should see a Windows XP graphic.
24.	Click Start, click Run, type \\IIS1\ROOT, and then click OK. You should see the contents of the Local Drive (C:) on IIS1.
25.	Right-click the EAPTLStoCorpnet connection, and then click Disconnect.

Summary

This paper described in detail the steps required to configure secure VPN remote access using PPTP, L2TP/IPSec, and EAP-TLS in a test lab with five computers simulating an organization intranet and the Internet.

Related Links

Conference.