Now, your Apache server is enabled with two-factor authentication, and the access to the web resources http://acme.org/mfa requires two-factor authentication.  

Clicking the link "click to access protected page", you'll be redirected to the DualShield SSO server to be authenticated with TFA: http://dualshield.deepnetlabs.com/...

 

 

Once you have successfully authenticated, you'll be redirected back to your web site and granted access to the protected page, /mfa/index.html