Certificate Replacement Overview

You can perform different types of certificate replacement depending on your company policy and requirements for the system that you are configuring. You can perform certificate replacement from the vCenter Server, by using the vSphere Certificate Manager utility, or manually by using the CLIs included with your installation.

VMCA is included in each vCenter Server deployment. VMCA provisions each node, each vCenter Server solution user, and each ESXi host with a certificate that is signed by VMCA as the certificate authority.

You can replace the default certificates. For vCenter Server components, you can use a set of command-line tools included in your installation. You have several options.

Replace with Certificates Signed by VMCA

If your VMCA certificate expires or you want to replace it for other reasons, you can use the certificate management CLIs to perform that process. By default, the VMCA root certificate expires after 10 years, and all certificates that VMCA signs expire when the root certificate expires, that is, after a maximum of 10 years.

Figure 1. Certificates Signed by VMCA Are Stored in VECS

You can use the following vSphere Certificate Manager options:

• Replace Machine SSL Certificate with VMCA Certificate
• Replace Solution User Certificate with VMCA Certificate

For manual certificate replacement, see Replace Existing VMCA-Signed Certificates with New VMCA-Signed Certificates.

Make VMCA an Intermediate CA

You can replace the VMCA root certificate with a certificate that is signed by an enterprise CA or third-party CA. VMCA signs the custom root certificate each time it provisions certificates, making VMCA an intermediate CA.

Note: If you perform a fresh install with a vCenter Server, replace the VMCA root certificate before you add ESXi hosts. If you do, VMCA signs the whole chain, and you do not have to generate new certificates.

Figure 2. Certificates Signed by a Third-Party or Enterprise CA Use VMCA as an Intermediate CA

You can use the following vSphere Certificate Manager options:

• Replace VMCA Root Certificate with Custom Signing Certificate and Replace All Certificates
• Replace Machine SSL Certificate with VMCA Certificate (multi-node enhanced linked mode deployment)
• Replace Solution User Certificate with VMCA Certificate (multi-node enhanced linked mode deployment)

For manual certificate replacement, see Use VMCA as an Intermediate Certificate Authority.

Do Not Use VMCA, Provision with Custom Certificates

You can replace the existing VMCA-signed certificates with custom certificates. If you use that approach, you are responsible for all certificate provisioning and monitoring.

Figure 3. External Certificates Are Stored Directly in VECS

You can use the following vSphere Certificate Manager options:

• Replace Machine SSL Certificate with Custom Certificate
• Replace Solution User Certificates with Custom Certificates

For manual certificate replacement, see Use Custom Certificates with vSphere.

You can also use the vSphere Client to generate a CSR for a machine SSL certificate (custom), and replace the certificate after the CA returns it. See Generate Certificate Signing Request for Machine SSL Certificate Using the vSphere Client (Custom Certificates).

Hybrid Deployment

You can have VMCA supply some of the certificates, but use custom certificates for other parts of your infrastructure. For example, because solution user certificates are used only to authenticate to vCenter Single Sign-On, consider having VMCA provision those certificates. Replace the machine SSL certificates with custom certificates to secure all SSL traffic.

Company policy often does not allow intermediate CAs. For those cases, hybrid deployment is a good solution. It minimizes the number of certificates to replace, and secures all traffic. The hybrid deployment leaves only internal traffic, that is, solution user traffic, to use the default VMCA-signed certificates.

ESXi Certificate Replacement

For ESXi hosts, you can change certificate provisioning behavior from the vSphere Client. See the vSphere Security documentation for details.

Table 1. ESXi Certificate Replacement Options

Option	Description
VMware Certificate Authority mode (default)	When you renew certificates from the vSphere Client, VMCA issues the certificates for the hosts. If you changed the VMCA root certificate to include a certificate chain, the host certificates include the full chain.
Custom Certificate Authority mode	Allows you to update and use certificates manually that are not signed or issued by VMCA.
Thumbprint mode	Can be used to retain 5.5 certificates during refresh. Use this mode only temporarily in debugging situations.