How Does the Agent Know Which Certificate to Supply?

When you configure GlobalProtect to use client certificates for authentication on Mac or Windows endpoints, GlobalProtect must present a valid client certificate to authenticate with the portal and/or gateways.
For a client certificate to be valid, it must meet the following four requirements:
  • Issued by the certificate authority (CA) you defined in the Certificate Profile of your portal and gateway configurations.
  • Specifies the client authentication purpose, which the certificate administrator specifies when creating the certificate.
  • Located in the certificate store as configured in the GlobalProtect portal agent configuration. By default, the GlobalProtect agent first looks for a valid certificate in the user store and, if none exists, then looks in the machine store. Because the user store takes precedence, if the GlobalProtect agent locates a certificate in the user store, it will not look in the machine store. To force the GlobalProtect agent to look for certificates in only one certificate store, configure the
    Client Certificate Store Lookup
    option in the appropriate GlobalProtect portal agent configuration.
  • Match any additional purpose specified in the GlobalProtect portal agent configuration. To specify an additional purpose, you must identify the object identifier (OID) for the certificate and configure the
    Extended Key Usage OID
    value in the appropriate GlobalProtect portal agent configuration. An OID is a numeric value that identifies the application or service for which to use a certificate and that is automatically attached to a certificate when it is created by a certificate authority (CA). For more information on specifying a common or custom OID, see Certificate Selection by OID.
When only one client certificate meets the requirements above, the agent automatically selects and uses that client certificate for authentication. However, when multiple client certificates meet the these requirements, GlobalProtect prompts the user to select the client certificate from a list of valid client certificates on the endpoint. While GlobalProtect requires users to select the client certificate only when they first connect, users might not know which certificate to select. In this case, we recommend you to narrow the list of available client certificates by certificate purpose (as indicated by the OID) and certificate store. For more information on these and other settings you can configure to customize your agent, see Customize the GlobalProtect Agent.

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