Web site development - Securing LinuxSince the dawn of interconnected networks, some
Securing LinuxSince the dawn of interconnected networks, some userhas been trying to break into other users systems. Asthe Internet has grown and broadband Internet access hasspread, the problem has only become more severe. A homecomputer running an insecure configuration can be used as apowerful mail relay, storage for traffic in pirated data, allowthe user s personal information to become compromised, orany number of other such horrors. Once upon a time network attacks required some effort andskill on the part of the attacker. Today automated tools canget even the most novice user up and running trying to com- promise network-attached systems in an alarmingly shorttime. Additionally, worms have the capability to turn largenumbers of insecure Win32 systems into an army of zombies usable for massive coordinated Denial of Service attacks. Why should you care about security? According to the InternetStorm Center (http://isc.sans.org), a computer connectedto the Internet has 16 minutes before it falls under some formof attack. Securing any computer system is not hugely difficult; it simply requires some common sense and careful applicationof good security practices. In many cases, good practices for setting and protecting pass- words, monitoring log files, and creating good firewalls willkeep out many would-be intruders. Sometimes, more proac- tive approaches are needed to respond to break-ins. Use thischapter to familiarize yourself, as a Linux administrator, withthe security dangers that exist and the tools necessary to pro- tect your system. 66CHAPTER …In This ChapterProtecting againstDenial of Service(DoS) attacksPreventing networkbreak-insUsing log files todetect intrusionsImproving securitywith strong passwordsUsing encryptiontechniquesSecurity auditing toolsGuarding yourcomputer withPortSentry …