GNU-Linux is the ultimate hacker’s playground. It’s a toy for the imagination, not unlike a box of blocks or a bag of clay. Whether someone is an artist or a scientist,

the possibilities are endless. Anything that you want to try to do and build and make with a computer is subject only to your creativity. This is why so many people are interested in Linux. Many call it Linux instead of GNU-Linux, its full name—much the same way you’d call a friend by a nickname. Perhaps this is due to the intimacy that you can achieve with this operating system through its source code. Or from the experience of being part of a special community. Whatever it is though, everyone can benefit from communicating with a machine that is honestly attributable to the transparency and openness of Linux.

Although not the dominant operating system on the Internet, Linux is quite prevalent, considering that the overwhelming majority of servers running web services, email services, and name services all depend on other open-source code that works with Linux. And this is where the trouble begins. Can something so open be properly secured? The difficulty begins when you need secure it. How do you secure something like this, with its collectively designed hosting components that are built, rebuilt, and reconfigured by whim and can differ from machine to machine? You will seldom find two identical systems. How then can you approach the possibility of providing security for all of them?

This edition of Hacking Exposed Linux is based on the work of ISECOM, an open security research organization with the mission to “Make sense of security.” ISECOM has thousands of members worldwide and provides extensive methodologies and frameworks in regards to security, safety, and privacy. ISECOM uses open collaboration and extensive peer review to obtain the highest possible quality research—which is also how this edition was developed. Many security enthusiasts and professionals collaborated to create a book that is factual, practical, and really captures the spirit of Linux. Only in this way can you expect to find the means of securing Linux in all of its many forms.