Two-Factor Authentication (2FA) is easy to integrate with Directadmin by using the SAASPASS Authenticator(works with google services like gmail and dropbox etc.) and it's Multi-Factor Authentication (MFA) capabilities. The SAASPASS Authenticator supports the time-based one-time password (TOTP) standards. Download the SAASPASS app and setup the SAASPASS Authenticator.
You can find additional information on activating SAASPASS Authenticator into Directadmin on this page.
The key differences between Google Authenticator and SAASPASS Authenticator: