VMware vCenter: Previous MACHINE_SSL_CERT Subject Alternative Name does not match new MACHINE_SSL_CERTIFICATE Subject Alternative Name

Paolo Caparrelli VMware 22 June 2022

Installing custom certificates into vCenter 6.7

The main objective is to have a HTTPS connection with no errors like this:

First of all, you will need three certificates in the following format:

root.cer of the Root CA (it can be internal or external CA). If you have an intermediate certificate, you must join the two certificates. Please check this article to do so;
certificate.cer generated by the Root/Intermediate CA. This is the certificate with the DNS name(s) that you want to change in vCenter. Something like vcenter.domain.local;
certificate.key of the main certificate (this is the private key)

If you don't have this format extension, you can always use OpenSSL to convert them: Download

Here are some examples:

Convert PFX to CRT/CER with certificate and private key

openssl pkcs12 -in certificate.pfx -clcerts -nokeys -out certificate.cer
openssl pkcs12 -in certificate.pfx -nocerts -out certificate.key

Convert PEM to PFX

openssl pkcs12 -export -out certificate.pfx -inkey certificate.key -in certificate.crt -certfile CACert.crt

Convert to multiple formats using a WebTool

With this certificates you are ready to start:

1. SSH to the vCenter server
2. Run the following command to enable and access the Bash shell:

shell.set –enable True
shell

3. In the Bash shell, run the following command to change the default shell to Bash:

chsh -s "/bin/bash" root

4. Copy the three certificates to vCenter server with WinSCP or similar. Copy them to /root/cert/
5. Return to the Appliance Shell by running the following command:

chsh -s /bin/appliancesh root

6. Enter the following command to manage the certificates

/usr/lib/vmware-vmca/bin/certificate-manager

     7. Choose option 1
     8. Provide the username and password of vCenter administrator
     9. Choose option 2
   10. Enter the full path to the main certificate.cer
   11. Enter the full path to the main certificate.key
   12. Enter the full path to the root CA root.cer

It can take a while, because all the services will be stopped and started, but in the end you will have your vCenter with HTTPS connection with the DNS name(s) you choose.

I had one error with my certificate:

Command Output: /root/cert/certificate.cer: OK
Status : 10% Completed [Replacing Machine SSL Cert…]
Previous MACHINE_SSL_CERT Subject Alternative Name does not match new MACHINE_SSL_CERTIFICATE Subject Alternative Name
Performing rollback of Machine SSL Cert…
Get site nameus : 0% Completed [Rollback Machine SSL Cert…]

For me that was not obvious, because my SAN was correct. So I investigated further and found that the new certificate had this Subject Alternative Names:

hostname.domain.com
cname.domain.com

But vCenter was expecting the following SANs:

hostname(s)
ipv6address

So, the simple solution is to create another certificate with IPv6 SANs (not for me, because it was a external certificate) or just disable the SAN check in the Python Script!

1. Edit with vi the file: /usr/lib/vmware-vmca/bin/certificate-manager
2. Comment line 594 and line 595 (see below)

#        if var.strip() in ['1']:
#            iscomparerequired = compare_certificate_san
or
#        if var.strip() in ['1']:
#            iscomparerequired = compare_certificate_san_to_pnid(cert_file)

3. Re-run the certificate manager
4. Check if everything is ok.

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