Sentry Two-Factor Authentication
The Sentry Two-Factor Authentication module is a free and open source extension for the Magento eCommerce platform. When activated, the extension requires two-factor authentication for all administrative users. Two-factor authentication requires both something you know (typically a password) and something you have (typically a mobile device) which increases overall authentication security. This Magento module was created in partnership between Nexcess and Human Element to greatly enhance security.