Linux® Bible 2009 Edition: Boot up Ubuntu®, Fedora®, KNOPPIX, Debian®, SUSE®, and 13 Other Distributions

Chapter 12. Securing Linux

IN THIS CHAPTER

• Linux security checklist

• Using password protection

• Monitoring log files

• Communicating with Secure Shell tools

• Understanding attack techniques

• Protecting servers with certificates

• Using special Linux security tools distributions

Since the dawn of interconnected networks, some users have been trying to break into other users' systems. As the Internet has grown and broadband Internet access has spread, the problem has become more severe. A home computer running an insecure configuration can be used as a powerful mail relay, provide storage for traffic in pirated data, allow the user's personal information to become compromised, or any number of other such horrors.

Once upon a time, network attacks required some effort and skill on the part of the attacker. Today, automated tools can get even the most novice user up and running trying to compromise network-attached systems in an alarmingly short time. Additionally, worms have the capability to turn large numbers of insecure systems into an army of "zombies" usable for massive, coordinated, distributed denial-of-service (DDoS) attacks.

Why should you care about security? According to the Internet Storm Center (http://isc.sans.org), a computer connected to the Internet has an average of 16 minutes before it falls under some form of attack. Securing any computer system is not hugely difficult; it simply requires some common sense and careful application of good security practices.

In many cases, good practices ...