How can you prevent users from seeing a security warning message when connecting to the Authentication Portal?

To prevent users from seeing a security warning message when connecting to the Authentication Portal, importing a custom self-signed certificate or a third-party certificate to your Firebox is the correct approach. When users connect to a service served by your Firebox, browsers check the server's certificate against a list of trusted certificate authorities.

If the Firebox uses a self-signed certificate that the user's browser does not recognize, the browser will display a security warning indicating an untrusted connection. By importing a certificate that is issued by a trusted certificate authority (CA) or creating a self-signed certificate that is installed on the users' devices, you establish a secure, trusted connection that users can access without any warning messages. This ensures that communications are encrypted and helps maintain user confidence in the security of the system.

Other choices may involve changing the configuration or user behavior but don't address the root cause of the security warning effectively. Simply replacing the Firebox certificate with a trusted certificate from an external web server would not work, as the certificate needs to be associated with the Firebox itself. Adding user accounts to a trusted list does not affect the browser's handling of certificates. Disabling security warnings in browsers could compromise overall security and is not a responsible solution.