@Michael.Thyme I understood how you want to use the two authentications of the portal and gateway and I wrote of low chances because it might be possible that somehow the process for the portal could have a problem while the gateway still works properly. Ok, the propability is extremely low, but in theory it is possible. I also read some things about the google_authenticator pam module and I came to the same conclusion as you: without some rewriting of the module it isn't possible that this authentication module will be access-challenge compatible. LinOTP is a very good idea I think. This way you will be able to configure the login flow in the LinOTP application (and in addition this software gives you way more possibilities about other configurations, user self registration, logging, ...)
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