1- Copy pam scripts
sudo cp pam-zoftoken.sh pam-zoftoken-echo.txt /usr/sbin
2- Edit pam file /etc/pam.d/common-auth (common-auth-example)
auth [success=1 default=ignore] pam_exec.so quiet /usr/sbin/pam-zoftoken [service] [no_2fa_user] [authkey] [host]
auth [success=die] pam_echo.so file=/usr/sbin/pam-zoftoken-echo.txt