I have been looking for a Two-Factor Authentication that works well with Zimbra open source edition.
One of the products I looked at - eToken PASS(http://www.safenet-inc.com/multi-factor-authentication/authenticators/one-time-password-otp/etoken-pass/) requires software running on Windows and I don't have any Windows servers in-house so will not work for me. Also, some of the users who are using Outlook won't be able to authenticate using this method.
More straight forward option was: http://www.safenet-inc.com/multi-factor-authentication/authenticators/pki-usb-authentication/. This is basically a SSL certificate in the USB key. Apparently this works with browsers as well as email clients and does't require any additional backend software for authentication. Does anyone have any experience integrating similar devices with Zimbra?
Another issue is that I only need this two-factor auth for a limited number of users on the server. Is this even possible?