This is a Roundcube webmail plugin that enables Duo Security Two Factor Authentication.
It creates an additional page after successful username/password authentication that requires a 2nd Factor of Authentication using Duo Security (push, sms, call, hardware token code).
Install using Composer (https://getcomposer.org) from the root directory of your roundcube installation:
Run $ composer require "lmr/duo_auth:>=1.0.7"
Run $ composer dumpautoload -o
Run cd plugins/duo_auth/
Run ln -s ../../vendor/duosecurity/duo_api_php/src/* .
Copy config.inc.php.dist to config.inc.php and modify as necessary.
Enter all keys necessary for integration with Duo in the config.inc.php file.
Assuming a Duo integration has already been created in Duo's Admin Panel, you will be able to find all the information requested in the config.inc.php there.
Author: Alexios Polychronopoulos - Wrote duo_auth for Roundcube.
Author: Leonardo Mariño-Ramírez - Updated the plugin for compatibility with Roundcube 1.3.0.
Author: Johnson Chow - Added support for IPv4 CIDR matching and 2FA overrride for specific users.