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Two-Factor Authentication System for Apache and SSH

If you run a publicly accessible Web server for your own use (and let’s face it, if you’re reading Linux Journal, there’s a very good chance you do), how do you go about limiting the risk of someone accessing your site and doing bad things? How about SSH, an even bigger concern? In today’s world, it’s imperative to think about your exposure and take steps to limit as much risk as possible.

In this tutorial, I walk through the steps necessary to implement a home-grown two-factor authentication system for accessing your Web sites and for SSH access.