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This chapter is from the book

Implementing Internet-Based Client Management

Internet-based client management in Configuration Manager 2012 is really just configuring key roles to support the secure HTTPS protocol rather than the insecure HTTP protocol. That said, considerable preparation work needs to be done to implement the Public Key Infrastructure and certificates to support this change efficiently and effectively.

Creating a Public Key Infrastructure

A Public Key Infrastructure (PKI) is an important aspect of the Configuration Manager 2012 implementation. When a certificate is issued, its usage is governed by an Object Identifier (OID). A certificate can have more than one OID, essentially allowing the certificate to be used for more than one purpose.

A certificate with the Client Authentication OID is required on all managed clients, including mobile devices, to communicate with a Configuration Manager site via HTTPS.

A certificate with the Server Authentication OID (1.3.6.1.5.5.7.3.1) and Client Authentication OID (1.3.6.1.5.5.7.3.2) is required on all Configuration Manager 2012 Site Systems, including Site Servers, Management Points, Distribution Points, Software Update Points, and State Migration Points. The Server Authentication certificate is used on each Site Server to encrypt communication between the managed systems and the Configuration Manager component.

Deploying an Active Directory Enterprise Root CA

This example details the steps required to deploy an Enterprise Root CA in the Company ABC domain. When an Enterprise Root CA is configured, all clients in the domain automatically trust certificates issued from this CA.

All Configuration Manager Site Servers and managed clients must trust the Certificate Authority. Any Configuration Manager Site Servers or managed clients that don’t trust this Certificate Authority will not communicate with the infrastructure and might become orphaned. This typically happens when non–domain member servers, such as bastion hosts in the demilitarized zone (DMZ), are not part of the domain but have a Configuration Manager agent installed. To correct this problem, install the CA certificate into the local computer’s Trusted Root Certificate Authorities certificates store.

To deploy an Enterprise Root CA, complete the following steps:

  1. Open the Server Manager console on CERT, the intended CA server.
  2. Select the Roles node.
  3. Click the Add Roles action.
  4. Click Next to skip the Roles Overview page.
  5. Enable the Active Directory Certificate Services role, and then click Next.
  6. Click Next to skip the AD CS overview page.
  7. Enable the Certification Authority role service.
  8. Enable the Certification Authority Web Enrollment role service.
  9. Click Add Required Role Services when prompted, and then click Next.
  10. Select Enterprise and click Next.
  11. Select Root CA and click Next.
  12. Select Create a New Private Key and click Next.
  13. Accept the default Cryptography settings and click Next.
  14. Accept the default CA Name settings and click Next.
  15. Accept the default Validity Period settings and click Next.
  16. Accept the default Certificate Database Location settings and click Next.
  17. Click Next to skip the IIS Overview page.
  18. Accept the default IIS Role Services and click Next.
  19. Confirm the installation selections and click Install.
  20. Wait for the installation to complete and click Close.

After implementing the CA, the CRL Distribution Point (CDP) settings need to be configured to allow HTTP access to the CRL files. For security reasons, this typically wouldn’t be done on the issuing CA; the CRL would be published on a system designated for that role. However, for demonstration purposes, the CRL will be published on the server CERT, allowing Internet-based clients to check the CRL.

To publish the CRL, complete the following steps:

  1. Open the Server Manager console on CERT.
  2. Expand the Roles node.
  3. Expand the Active Directory Certificate Services node.
  4. Right-click companyxyz-CERT-CA and click Properties.
  5. Select the Extensions tab.
  6. Select http://<ServerDNSName>/CertEnroll/<CaName>... from the list of CDPs.
  7. Enable Include in CRLs. Clients use this to find Delta CRL locations.
  8. Enable Include in the CDP Extension of Issued Certificates.
  9. Apply the changes, click Yes when you are prompted to restart the Active Directory Certificate Services, and then click OK to close the window.

Validating the Enterprise Root CA

The newly installed Enterprise Root CA should be validated before certificates are issued to clients. To validate the CA, check the local application event log on the server CERT. This can be accessed through the Diagnostics node of Server Manager.

If the application event log is clean and doesn’t contain any error or warning messages about Certificate Services or related components, the server should be ready to issue certificates to clients. It is always a good practice to restart the certificate server to ensure the Certificate Services can start and stop without logging any issues. It is also important to resolve all problems before moving to the next section and deploying certificates to managed clients and Site Servers.

Deploying Certificates

An enterprise Certificate Authority simplifies management of certificates by providing a secure, scalable certificate provisioning process through Active Directory. This task assumes all of the Configuration Manager servers and the Enterprise Root CA server have been moved to an organizational unit (OU) called Servers, and all of the workstations have been moved to an OU called Workstations.

The Servers and Workstations OUs are child objects of an OU called Managed. The Managed OU is located in the root of the domain.

Configuring the Auto-Enrollment Group Policy Object

A Group Policy Object (GPO) called Certificate Auto-Enrollment will be created and linked to the Servers OU and the Workstations OU. This group policy will be used to enable the certificate auto-enrollment function for all managed systems.

To create the Certificate Auto-Enrollment GPO, complete the following steps:

  1. Open the Group Policy Management Console on DC1.
  2. Expand Forest: companyabc.com.
  3. Expand Domains.
  4. Expand companyabc.com.
  5. Select the Group Policy Objects container.
  6. Right-click the Group Policy Objects container and select New.
  7. Enter Certificate Auto-Enrollment in the Name field and click OK.

Once the GPO has been created, the setting that allows Certificate Auto-Enrollment can be enabled.

To enable the Certificate Auto-Enrollment setting in the GPO, complete the following steps:

  1. Right-click the Certificate Auto-Enrollment GPO and select Edit.
  2. The Group Policy Management Editor opens.
  3. Expand Computer Configuration.
  4. Expand Policies.
  5. Expand Windows Settings.
  6. Expand Security Settings.
  7. Select the Public Key Policies container.
  8. Double-click Certificate Services Client - Auto-Enrollment.

    The Certificate Services Client - Auto-Enrollment location is shown in Figure 3.20.

    Figure 3.20

    Figure 3.20 Certificate Services Client - Auto-Enrollment.

  9. Select Enabled as the Configuration Model.
  10. Enable the option to Renew Expired Certificates.
  11. Enable the option to Update Certificates That Use Certificate Templates.
  12. Click OK to save changes and close the Group Policy Management Editor.

Once the Auto-Enrollment setting within the GPO has been configured to allow automatic certificate enrollment, the GPO can be linked to the correct OUs.

To link the Certificate Auto-Enrollment GPO to the correct OUs, complete the following steps:

  1. Open the Group Policy Management Console.
  2. Expand the Managed OU and select the Servers OU.
  3. Right-click the Servers OU and select Link an Existing GPO.
  4. Select Certificate Auto-Enrollment from the list of GPOs and click OK.
  5. Right-click the Workstations OU and select Link an Existing GPO.
  6. Select Certificate Auto-Enrollment from the list of GPOs and click OK.

When this is complete, any domain member server or workstation placed in the corresponding OUs will be configured for automatic certificate enrollment. To complete the process, a certificate template with the correct settings and permissions needs to be created and then published.

Configuring Certificate Templates

The next step is to create certificate templates with the appropriate settings and permissions. The permissions on the certificate template govern the clients’ ability to request the certificate. This is important because only the required certificates should be deployed to the system.

Creating the Client Authentication Certificate Template

Security permissions on the certificate template for Client Authentication will be configured to allow the domain computers security group to automatically request and receive this certificate through Active Directory. All systems in the Workstations and Servers OUs will receive this certificate.

To create Client Authentication templates for auto-enrollment, complete the following steps:

  1. Open the Server Manager console on CERT.
  2. Expand the Roles node.
  3. Expand the Active Directory Certificate Services node.
  4. Select the Certificate Templates container.

    The Certificate Templates container is shown in Figure 3.21.

    Figure 3.21

    Figure 3.21 The Certificate Templates container.

  5. Right-click the Workstation Authentication template.
  6. Select Duplicate Template.
  7. Choose Windows Server 2003 Enterprise and click OK.
  8. Type Client Certificate Auto-Enrollment in the Template Display Name field.
  9. Select the Security tab.
  10. Enable the Autoenroll permission for domain computers.
  11. Select the Extensions tab.
  12. Select the Application Policies item.
  13. Verify the description states Client Authentication.
  14. Click Apply and then click OK to close the window.

Creating the OS Deployment Template

Security permissions on the certificate template for OS Deployment will be configured to only allow manual certificate requests. Before PXE Service Points are implemented, the Client Authentication OS Deployment certificate will be requested through the web enrollment page.

To create the OS Deployment template, complete the following steps:

  1. Open the Server Manager console on CERT.
  2. Expand the Roles node.
  3. Expand the Active Directory Certificate Services node.
  4. Select the Certificate Templates container.
  5. Right-click the Workstation Authentication template.
  6. Select Duplicate Template.
  7. Choose Windows Server 2003 Enterprise and click OK.
  8. Type Configuration Manager OS Deployment in the Display Name field.
  9. Select the Issuance Requirements tab.
  10. Enable CA Certificate Manager Approval.
  11. Select the Request Handling tab.
  12. Enable the Allow Private Key to Be Exported option.
  13. Select the Subject Name tab.
  14. Enable the Supply in the Request option.
  15. Select the Security tab and remove Domain Computers from the list.
  16. Click Apply and then click OK to close the window.

Creating the Server Authentication Certificate Template

Security permissions on the certificate template for Server Authentication will be configured to only allow a custom security group to automatically request this certificate through Active Directory. Ultimately, all systems that will host web services will receive this certificate.

Before executing the next task, create a universal security group called SCCM Site Servers in the domain. Add the Configuration Manager servers and the Certificate Authority server to this group.

To create Server Authentication template for auto-enrollment of the SCCM Site Servers, complete the following steps:

  1. Open Server Manager and expand Roles, expand Active Directory Certificate Services, and select the Certificate Templates container.
  2. Right-click the Workstation Authentication template.
  3. Select Duplicate Template.
  4. Choose Windows Server 2003 Enterprise and click OK.
  5. Type Server Certificate Auto-Enrollment in the Display Name field.
  6. Select the Security tab.
  7. Remove the Domain Computers security group.
  8. Click Add, type the group SCCM Site Servers, and then click OK.
  9. Highlight SCCM Site Server.
  10. Uncheck the Read permission.
  11. Check the Enroll and Autoenroll permissions.

    The permission for this certificate is shown in Figure 3.22.

    Figure 3.22

    Figure 3.22 Permissions for the Server Authentication template.

  12. Select the Extensions tab.
  13. Select the Application Policies extension item and click Edit.
  14. Highlight the Client Authentication Policy and click Remove.
  15. Click Add, choose Server Authentication from the list, and then click OK.
  16. Click OK, click Apply to apply the settings, and close the window.

All servers that are added to the Servers OU and are members of the SCCM Site Servers security group will receive a certificate that can be used for server authentication.

Publishing the Certificate Templates

Now that the Client and Server Authentication certificates have been created, they can be published. This tells the Certificate Authority the template is available for client consumption.

To publish the authentication templates for auto-enrollment, complete the following steps:

  1. Open Server Manager on CERT.
  2. Expand Roles.
  3. Expand Active Directory Certificate Services.
  4. Expand companyxyz-CERT-CA.
  5. Select the Certificate Templates container.

    The CA Certificate Templates container is shown in Figure 3.23.

    Figure 3.23

    Figure 3.23 The CA Certificate Templates container.

  6. Right-click Certificate Templates.
  7. Click New and then click Certificate Template to Issue.
  8. Select the Client Certificate Auto-Enrollment template from the list.
  9. Hold down the Ctrl key.
  10. Select the Server Certificate Auto-Enrollment template from the list.
  11. Select the Configuration Manager OS Deployment template from the list.
  12. Click OK to complete the process.

The three certificates should be listed in the Certificates Template container for the CA. These certificates are ready for consumption by Configuration Manager Site Servers and managed clients.

Configuring the Certificate Services Website for SSL

Certificates cannot be issued with the Certificate Services Enrollment web server unless it is configured to use SSL. This section describes the steps needed to secure the website with a server certificate. This also validates the ability for the certificate server to issue certificates.

To configure the Certificate Services website for SSL, complete the following tasks:

  1. Open the command prompt on CERT.
  2. Type gpupdate /force to refresh the group policies.
  3. After the group policy is refreshed, open Server Manager.
  4. Expand Roles.
  5. Expand Active Directory Certificate Services.
  6. Expand companyxyz-CERT-CA.
  7. Select the Issued Certificates container.

The two new certificates should be listed in the container.

The CA Issued Certificates container is shown in Figure 3.24.

Figure 3.24

Figure 3.24 The CA Issued Certificates container.

The server CERT has received both the client and server signing certificate. The server signing certificate can be used to secure the Certificate Services website.

To secure the Certificate Services website, complete the following steps:

  1. Open the Server Manager on CERT.
  2. Expand Roles.
  3. Expand Web Server (IIS).
  4. Select Internet Information Services.
  5. Expand the CERT web server.
  6. Expand Sites.
  7. Select Default Web Site.
  8. Select Bindings from the Actions pane.
  9. Click Add.
  10. Select HTTPS for the binding type.
  11. Select the correct certificate from the SSL certificate menu.
  12. Click View to verify the correct certificate has been selected and then click OK.
  13. Click OK and then click Close.

To test the newly installed certificate, open Internet Explorer and browse to the URL https://cert.companyxyz.com/certsrv. The Certificate Enrollment web page should open. Click the small lock icon beside the address bar, which shows the status of the certificate and that the Certificate Authority companyxyz-CERT-CA has identified this computer as cert.companyabc.com.

Configuring the WSUS Website for SSL

Because the WSUS component was installed on the CM1 server, the same certificate that was used to secure the Default Site can be used to secure the WSUS Administration site from within IIS.

To configure WSUS for SSL communication, complete the following steps:

  1. Open Internet Information Services Manager.
  2. Expand Sites, and select the WSUS administration site, which is often the Default Web Site.
  3. Click the Bindings action.
  4. Click Add, select HTTPS, and click Edit.
  5. Choose the certificate from the list.
  6. Click View to verify the correct certificate was selected, click OK, and then click Close.
  7. Select the APIRemoting30 virtual directory.
  8. Double-click the SSL Settings option.
  9. Enable the Require SSL option and click Apply.
  10. Repeat for the ClientWebService, DSSAuthWebService, ServerSyncWebService, and SimpleAuthWebService virtual directories.

When the WSUS virtual directories are correctly configured, run the following command on the WSUS server to finalize the configuration needed to support SSL:

WSUSUtil.exe configuressl cm1.companyxyz.com

This utility is located in the Tools folder located within the WSUS installation folder. By default, this is folder is c:\Program Files\Update Services\Tools.

Requesting the OS Deployment Certificate

The OS Deployment client certificate is used by all systems during the OS deployment. This is essentially a shared certificate that is imported when the PXE Service Point is established.

The same procedure used to request the Document Signing certificate can be used to request the OS Deployment certificate. The main differences are instead of selecting the Configuration Manager Document Signing template from the template list, the Configuration Manager OS Deployment template must be selected. In the Name field, enter osd01.companyxyz.com.

Remember to approve the certificate osd1.companyxyz.com from within the Pending Requests container. When exporting the certificate, enter c:\Temp\OSD01.pfx as the file.

Enabling Internet-Based Client Management

In Configuration Manager 2012, the Site Servers roles have to be explicitly configured to enable Internet-based client management (IBCM). Each Management Point and Distribution Point that are to be enabled for IBCM will need to be configured to communicate over HTTPS rather than HTTP. This is typically done on one or more systems dedicated to handling Internet traffic, but the actual configuration can depend on specific business and security requirements.

When a client communicates over the Internet, it needs to communicate with the following:

  • Management Point
  • Distribution Point
  • Software Update Point
  • Fallback Status Point
  • Enrollment Proxy Point
  • Application Catalog Website Point

All communication is done over HTTPS, with the exception of the Fallback Status Point, which communicates over HTTP. The first step in the process is to enable IBCM on the Site Server.

The FSP and SUP do not require additional configuration and are automatically enabled with the Site Server. Finally, to support IBCM, the following ports need to be open from the Internet:

  • CRL Web Site: TCP 80
  • Fallback Status Point: TCP 80
  • Management Point: TCP 443
  • Distribution Point: TCP 443
  • Software Update Point: TCP 443

It is not recommended to connect any internal system directly to the Internet; for production deployments, consider using a reverse proxy, such as the Microsoft Threat Management Gateway (TMG).

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