There are many objectives and goals to be considered when securing a operating system. When configuring Unix operating system security, consider the critical principles of security known as the confidentiality, integrity, and availability (CIA) triad. In addition to incorporating security controls that relate to the CIA triad, three other security features directly affect CIA and aid the overall site security program: access control, auditing, and backups. Although this chapter covers general Unix considerations, it also addresses several Linux specific items. This chapter is for all Linux variants: file names, directory paths, variable names, and so on, may also have to be taken into consideration. There are numerous versions of Linux, and it would be beyond the scope of this chapter to try to detail them all. All requirements listed within this chapter will pertain to all versions of Linux unless explicitly noted otherwise.