Becoming a "Linux Security Artist"
After forty years in the commercial computing business, the one idea that has been drilled into me by security professionals is the fact that there is no such thing as a secure computer system, only levels of insecurity. Therefore the cost of keeping the information and system secure has to be balanced with the cost of losing that information or system, or having it damaged. Unfortunately the speed and availability of the Internet combined with the low cost of very powerful computers and network services have made the cost of “cracking” go down and the cost of “securing” go up.
The most important thing in a secure system is to have a good security policy. Without that, you are lost and will wander ineffectively. Therefore you have to give thought as to who will be able to do what, whether those limitations are discretionary or mandatory and how you will implement and enforce those policies. A good example of not having a good policy is the company that forces all of their employees to have long, complicated passwords that change once a week, but tolerate people writing their passwords on sticky notes and pasting it on their LCD panels “because they can not remember the passwords.”