Installing and configuring required packages

Installing the Google Authenticator PAM module

Start a terminal session and type:

sudo apt install libpam-google-authenticator

Configuring SSH

To make SSH use the Google Authenticator PAM module, add the following line to the /etc/pam.d/sshd file:

auth required pam_google_authenticator.so

Now you need to restart the sshd daemon using:

sudo systemctl restart sshd.service

Modify /etc/ssh/sshd_config – change ChallengeResponseAuthentication from no to yes, so this part of the file looks like this:

Change to yes to enable challenge-response passwords (beware issues with
some PAM modules and threads)
ChallengeResponseAuthentication no # CHANGE THIS TO YES
Change to no to disable tunnelled clear text passwords
#PasswordAuthentication yes

Configuring authentication

In a terminal, run the google-authenticator command.

It will ask you a series of questions, here is a recommended configuration:

• Make tokens “time-base””: yes
• Update the .google_authenticator file: yes
• Disallow multiple uses: yes
• Increase the original generation time limit: no
• Enable rate-limiting: yes

2FA with cockpit

Add at the end of the file /etc/pam.d/cockpit

auth required pam_google_authenticator.so nullok

then restart cockpit

systemctl restart cockpit