Chapter 9: Securing Linux

Securing a Linux machine is usually a balancing act. The endgame is essentially protecting data from unwanted access. While there are many ways to achieve this goal, we should adopt the methods that yield maximum protection, along with the most efficient system administration. Gauging the attack and vulnerability surfaces, both internal and external, is always a good start. The rest of the work is building fences and putting on armor – not too high and not too heavy. The outer fence is a network firewall. Internally, at the system level, we build application security policies. This chapter introduces both, albeit the art of the balancing act is left to you.

In the first part of this chapter, we'll look at access control mechanisms and the related security modules – SELinux and AppArmor. In the second part, we will explore packet filtering frameworks and firewall solutions.

After completing this chapter, you will have become acquainted...