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Certification Authorities (CAs) issue certificates for a number of different purposes. In the context of your ISA Server firewall/VPN server, a CA can provide a certificate that allows:

 

 

• L2TP/IPSec VPN connections from VPN clients

 

VPN clients can establish L2TP/IPSec connections to the ISA Server firewall/VPN server. A machine certificate is required to create the IPSec encrypted tunnel.

 

 

• L2TP/IPSec VPN connections from VPN gateways (VPN      routers)

 

Remote VPN gateways can call the ISA Server firewall/VPN server and establish a gateway to gateway link. VPN gateways act as VPN routers and allow packets to be routed between networks through a the VPN tunnel established between the VPN gateways.

 

 

• L2TP/IPSec VPN connections to VPN servers

 

The ISA Server firewall/VPN server may need to establish a VPN client connection to a VPN server. For example, some Internet Service Providers require machines to establish a VPN connection with their own VPN server to obtain a public address for the ISA Server firewall/VPN server’s external interface. In this case. the ISA Server firewall/VPN server is a VPN client to the ISP’s VPN server.

 

 

• Certificate-based user authentication using a      certificate stored on the user machine

 

Users can obtain certificates and use those certificates to authenticate with the VPN server. The user certificate is stored on the user’s computer and a VPN connectoid (dial-up connection) can be configured to present this certificate during the PPP (in this case, EAP-TLS) user authentication process.

 

 

• Certificate-based user authentication using a      certificate stored on a Smart Card

 

A user certificate can be stored on a Smart Card. The user certificate is stored on a Smart Card and the VPN connectoid is configured to present the Smart Card certificate during the PPP (in this case, EAP-TLS) user authentication process.

 

 

A Microsoft Certificate Server can take on one of four roles:

 

 

•  Enterprise Root CA
•  Enterprise Subordinate CA
• Stand-alone  Root CA
• Stand-alone Subordinate CA

 

 

A Microsoft Enterprise CA has the following characteristics:

 

 

• The enterprise CA must be a      member of a Windows 2000 or Windows Server 2003 Active Directory domain
• The enterprise  Root CA certificate is automatically      added to the Trusted Root      Certification Authorities node for all users and computers in the      domain
• User certificates can be issued      that allow users to log on to the Active Directory domain using      computer-stored certificates or certificates installed on Smart Cards
• User certificates and the      Certificate Revocation List (CRL) are stored in the Active Directory
• In contrast to stand-alone CAs,      an enterprise CA issues certificates via certificate templates that can be added and customized by the      CA administrator
• In contrast to the stand-alone      CA, the enterprise CA confirms the credentials of the user requesting a      certificate
• The subject name (the name of the user or computer) on the      certificate can be entered manually or automatically

 

 

We recommend that you install an Enterprise CA if:

 

 

• You have an Active Directory      domain, and/or
• You require automatic      deployment of certificates to users and computers

 

 

The enterprise CA is the ideal solution for any network with a Windows 2000 or Windows Server 2003 domain. All domain members can be assigned certificates via Group Policy based certificate autoenrollment. You can limit the scope of autoenrollment by assigning permissions to the certificate template used for autoenrollment. Users and computers that are not domain members can use the Web enrollment site to obtain certificates.

 

 

If you want to support certificate enrollment via Web enrollment site, then you must install the Internet Information Services World Wide Web service before installing Microsoft Certificate Services.

 

 

In this ISA Server 2000 VPN Deployment Kit document we cover the following procedures:

 

 

• Installing the Internet      Information Services 6.0 World Wide Web service (W3SVC) to support the      enterprise CA Web enrollment site
• Installing the Windows Server      2003 Certificate Services on a domain controller. The CA is installed as      an enterprise CA.

 

 

      Note:
You can install an enterprise CA on any domain member. The machine does not need to be a domain controller.

 

 

Installing Microsoft Internet Information Services World Wide Web Service

 

 

Perform the following steps to install IIS 6.0 on the Windows Server 2003 member server or domain controller computer that will be the enterprise CA:

 

 

1. Click Start, point to Control      Panel and click Add or Remove      Programs.
2. Click the Add/Remove Windows Components button in the Add or Remove Programs window      (figure 1).

 

 

Figure 1 (fig111)

 

 

 

1. On the Windows Components window, click on the Application Server entry and click the Details button (figure 2).

 

 

Figure 2 (fig112)

 

 

 

1. On the Application Server page, click on the Internet Information Services (IIS) entry and click the Details button (figure 3).

 

 

Figure 3 (fig113)

 

 

 

1. IN the Internet Information Service (IIS) dialog box, put a checkmark      in the World Wide Web Service      checkbox and click OK (figure      4).

 

 

Figure 4 (fig114)

 

 

 

1. Click OK on the Application      Server dialog box (figure 5).

 

 

Figure 5 (fig115)

 

 

 

1. Click Next on the Windows      Components dialog box (figure 6).

 

 

Figure 6 (fig116)

 

 

 

1. Click Finish on the Completing      the Windows Components Wizard page (figure 7).

 

 

Figure 7 (fig117)

 

 

 

 

Installing Microsoft Certificate Services

 

 

Perform the following steps to install and configure an enterprise CA on a Windows Server 2003 computer:

 

 

      Note:
You must install the enterprise CA on a member server or domain controller on your internal network.

 

 

1. At a member server or domain      controller in your internal network, log on as a domain administrator.      Click Start, point to Control Panel and click Add/Remove Programs.
2. In the Add or Remove Programs window (figure 8), click the Add/Remove Windows Components      button.

 

 

Figure 8 (fig100)

 

 

 

1. In the Windows Components dialog box (figure 9), click on the Certificate Services entry and      click the Details button.

 

 

Figure 9 (fig101)

 

 

 

1. In the Certificate Services dialog box, put a checkmark in the Certificate Services CA checkbox      (figure 10). A Microsoft      Certificate Services dialog box appears and informs you that you can      not change the machine name or the domain membership of the machine while      it acts as a certificate server. Read the information in the dialog box      and click Yes.

 

 

Figure 10 (fig102)

 

 

 

1. Both the Certificate Services CA and Certificate Services Web Enrollment Support checkboxes are      checked (figure 11). Click OK      in the Certificate Services dialog      box.

 

 

Figure 11 (fig103)

 

 

 

1. Click Next in the Windows      Components dialog box (figure 12).

 

 

Figure 12 (fig104)

 

 

 

1. Select the Enterprise root CA option on the CA      Type page (figure 13). Click Next.

 

 

Figure 13 (fig118)

 

 

 

1. On the CA Identifying Information page (figure 14), type in a Common name for this CA. The      common name of the CA is typically the DNS host name or NetBIOS name      (computer name) of the machine running Certificate Services. In this      example, the name of the machine is WIN2003DC,      so we enter WIN2003DC in the Common name for this CA text box.      The default Validity Period of      the CA’s self-signed certificate is 5 years. Accept this default value      unless you have a reason to change it. Click Next.

 

 

Figure 14 (fig106)

 

 

 

1. On the Certificate Database Settings page (figure 15), use the      default locations for the Certificate      Database and Certificate      Database Log. You do not need to specify a shared folder to store      configuration information because this information will be stored in the      Active Directory. Click Next.

 

 

Figure 15 (fig107)

 

 

 

1. Click Yes on the Microsoft      Certificate Services dialog box (figure 16) informing you Internet      Information Services must be temporarily stopped.

 

 

Figure 16 (fig108)

 

 

 

1. Click Yes on the Microsoft      Certificate Services dialog box (figure 17) informing you Active      Server Pages must be enabled on IIS if you wish to use the Certificate      Services Web enrollment site.

 

 

Figure 17 (fig109)

 

 

 

1. Click Finish on the Completing      the Windows Components Wizard page (figure 18).

 

 

Figure 18 (fig110)

 

 

 

1. Close the Add or Remove Programs window.

 

 The Enterprise Certificate Authority is now installed and can issue certificates without requiring a machine restart.


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