Should concurrent SSH logins with two factor authentication work fine on Ubuntu 14.04?
I wish to set up SSH two factor authentication and have followed the guidelines at 'https://www.digitalocean.com/community/tutorials/how-to-protect-ssh-with-two-factor-authentication' to the letter. In fact, I have re-loaded the Ubuntu 14.04 OS & repeated these guidelines again. At login, in both cases, I get 'permission denied'.
If I remove the two changes to /etc/pam.d/sshd and /etc/ssh/sshd_config & restart the ssh service, I can log in successfully but it is the normal password only authentication.
My system only has a single user (ie. in addition to root) and I am logged in as that user to make the changes. Is the fact that I am already logged in causing the subsequent attempt to login in after the two factor authentication changes have been made causing a concurrent login conflict, resulting in the 'permission denied' ?
If concurrent google-authenticator logins should work, do you have any other ideas? There seems to be plenty of posts indicating the guidelines should work.