/usr/share/pam-configs/duo-unix is in libpam-duo 1.9.6-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | Name: Duo Security two-factor authentication
Default: no
Priority: 100
Auth-Type: Additional
Auth:
[success=ok default=bad] pam_duo.so
|