Secure OS Environments for Linux

In this paper I make a review of the main set of tools and resources available for Linux system administrators willing to build an operating system with enhanced security features that allow applications to run securely in a network accessible from the Internet. I have summarized the state of the art in this subject by offering an overview of the tools, compiling the most useful references and classifying them accordingly. The ultimate goal of the paper is to make more affordable the initial work for anyone interested in this topic.