Migration Advisory for CA Server Upgrade

Question

Dear Team,

We are planning to migrate a CA server and would like to clarify the below concerns before executing the same. The current CA server is configured on a production domain controller and the same server is configured with production NPS server/ service as well.

Current Environment

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• Have 03 Domain Controllers (DC01, DC02, DC03)
• One of the DC (DC03) is having the following server roles deployed
  • ADDS and DNS
  • CA
  • NPS
  • VA

Planned Migration Approach

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Migrating the current CA with a new server with new server name. However, this is also something we'd like to clarify, when existing NPS clients are to renew their certificates with the newly introduced CA, there will be an issue with the communication due to the new server is having a different host name than the previous server.

Also, the ultimate goal is to migrate the exiting CA, NPS and VA server roles to newly introducing individual servers and lastly upgrading the DC server and keeping it with the same name.

We are seeking your expertise to verify, what would be the best approach to achieve the overall end goal of this total requirement. Looking forward to hearing from you soon.

Kindly note, the existing CA server cert will be expired in 2 weeks time from today.

Answer 1

Hi,

Migrating a Certification Authority (CA), Network Policy Server (NPS), and other roles from a domain controller to new servers is a significant task that requires careful planning to ensure continuity of services and security. Given the complexity of the migration and the tight timeline due to the impending certificate expiration, here's an outlined approach to address your concerns and achieve your goals:

1. Pre-Migration Preparation

• Backup: Ensure you have complete backups of the CA database, private keys, and configuration settings. Similarly, backup NPS and VA (Virtualization Administrator, if that's what VA refers to) configurations.
• Documentation: Document all current configurations, including certificate templates, policies, and any custom settings.
• Environment Assessment: Verify the health of your Active Directory and DNS settings to ensure a smooth migration process. Use tools like dcdiag and repadmin to check for issues.

2. CA Migration Steps
3. Prepare the New CA Server:
   • Install the necessary roles on the new server. If you're keeping the CA role integrated with a domain controller, prepare accordingly; otherwise, consider a dedicated server for the CA role.
   • Ensure the new server meets all CA role requirements, including OS version, network settings, and security configurations.
4. Migrate the CA Role:
   • Use the "Backup CA" feature to backup CA settings, certificates, and private keys from the old server.
   • On the new CA server, install the CA role and select the option to "Restore a CA" during the configuration wizard, importing the backup taken from the old CA.
5. Update AIA and CDP Paths:
   • Adjust the Authority Information Access (AIA) and Certificate Revocation List Distribution Point (CDP) paths to reflect the new server's details. This is critical for ensuring clients can verify certificate status and chain.
6. Reissue Certificates if Necessary:
   • Depending on your environment, you may need to reissue some certificates, especially if they reference the old CA server directly by name.
7. NPS Migration

• Export Configuration: Use netsh nps export to back up the NPS configuration from the old server.
• Prepare the New NPS Server: Install NPS role on the new server.
• Import Configuration: Use netsh nps import to import the configuration to the new NPS server.
• Update RADIUS Clients: Ensure all RADIUS clients are updated to point to the new NPS server for authentication.

4. Handling NPS Clients and Certificates

• Renew Certificates: Before the migration, renew any certificates that are about to expire to avoid service disruption.
• Update Clients: If certificates or NPS clients reference the old CA by name, update them to trust the new CA. This may involve deploying new certificates through Group Policy or manually configuring clients.

5. Post-Migration Tasks

• Verify Services: Ensure all services are running correctly on the new servers, including testing certificate validation, RADIUS authentication, and other dependent services.
• Decommission Old Server: Once you've confirmed the new servers are functioning correctly, decommission the old CA/NPS server following best practices. Ensure no services are unexpectedly depending on the old server.

6. Upgrade Domain Controller

• Plan the DC Upgrade: With the CA, NPS, and VA roles migrated, plan the DC upgrade. This might involve updating the Operating System and ensuring all services are compatible with the new environment.
• Test: Before proceeding with the upgrade, ensure compatibility and perform a thorough test in a lab environment to anticipate any issues.

Important Considerations

• Timeline and Certificate Expiry: With the CA certificate expiring in 2 weeks, prioritize the CA migration and certificate renewal to avoid service disruptions.
• Communication: Inform stakeholders and users of potential downtimes or changes they may encounter during the migration process.

Migrating critical infrastructure roles like CA, NPS, and VA requires meticulous planning and execution to ensure security and service availability. Following the outlined steps and preparing for each phase of the migration will help achieve a smooth transition.

Answer 2

Dear Emmanuel,

Thank you very much for your prompt response.
First and foremost my apologies for not mentioning the name of VA service. It is Volume Activation Management Tool (VAMT). Furthermore, I'd like to clarify below concerns too.

In the 1st process mentioned below, we must use a different name for the new CA server and registry restoration must be happen after changing the host name value to aligning to the new CA server name right?

In the 2nd process mentioned below, how can we perform that activity? Could you please share the steps to perform the same?

In the 3rd process mentioned below, what would be the best approach to perform the same, as when we migrated the CA to the new server with a new host name, please let us know how should we renew the client certificates? Does the NPS certificate renew automatically with the new CA server or we should do it manually, if we should do it manually, should we do it ASAP and the what will be the NPS user experience?

1. Migrate the CA Role:
   • Use the "Backup CA" feature to backup CA settings, certificates, and private keys from the old server.
   • On the new CA server, install the CA role and select the option to "Restore a CA" during the configuration wizard, importing the backup taken from the old CA.
2. Update AIA and CDP Paths:
   • Adjust the Authority Information Access (AIA) and Certificate Revocation List Distribution Point (CDP) paths to reflect the new server's details. This is critical for ensuring clients can verify certificate status and chain.
3. Reissue Certificates if Necessary:
   • Depending on your environment, you may need to reissue some certificates, especially if they reference the old CA server directly by name.

After performing the CA server migration we'll get back to you on the remaining clarifications, and looking forward to hearing from you soon for the above clarifications related to the CA server migration.