From logging your system's activities to sniffing out rootkits, this chapter presents recipes to help protect the investment you've made in your system and its data against various threats. First, you'll learn how to set up a central log server using Syslog, and then, how to rotate log files to make sure that they don't grow out of control. Then, we'll look at how Tripwire is used to detect system intrusion by checking if changes have been made to important system files. This chapter also contains recipes for setting up ClamAV and chkrootkit to keep your system free of viruses, Trojans, rootkits, and other malware. We'll finish with how to set up a centralized backup server using Bacula to safeguard your data from everyday threats such as accidental deletion and hardware failures.