75 Ways to Secure Your Linux/Mac/Windows Systems With Open Source: "With online crime on the rise, it's more important than ever to protect your systems. But you don't have to pay a lot of money for security. The open source community continues to produce (and maintain) excellent tools that fulfill a wide variety of security needs.
This year, we've once again updated our list of top open source security apps. While the list isn't exhaustive by any means, we tried to include many of the best tools in a variety of categories. We dropped a few projects from last year's list that have gone inactive or closed source, and we've added a few newcomers that are worth your consideration."