There are 5 things that every good Linux Administrator knows. Do you know what they are?
They are in no particular order of importance:
1. Users are a Necessary Evil - Do you ever wonder why System Administrators seem so annoyed by you and your questions? It's because you are, in fact, an annoyance to them. Don't be insulted by this--it's just fact. You are generally the reason they exist but life would be easier for them if you didn't exist or ever need anything from them.
Take a deep breath and realize that you have a symbiotic relationship with your users. They probably don't like you either.
2. The Biggest Security Risks are Internal - As any good security expert will tell you, most security issues arise from inside a corporate network not from the outside. Most port scans, virus attacks, hacks, password stealing, and stolen data occurs from within your own ranks. Linux Administrators have the advantage of using a Unix Operating System that is inherently secure by virtue of the limited ability of users to damage the system.
Local users still pose the biggest security threats to a system through the download and use of rootkits, port scanners, and password crack programs.
Create Use or Terms of Service Policies that describe acceptable use and behavior. Make hack attempts a terminable offense.
3. Network Services are System Doorways - Any network service provides access to your system--which means service to your users and potential security risks. Network services are as necessary as users but also provide a way in for those with unsavory intentions.
Use chrooted services or separate (virtual) systems for services and run those services under ordinary user accounts.
4. Documentation is a Job Requirement - Whether or not you stay in a job for 1 year, 10 years, or for your entire career, you need to document changes, upgrades, updates, and how things work in your environment. You don't need to create a cookbook but a year or two from now, you may not remember the changes you made to the mail server to get it to relay local network traffic.
Documentation is a good thing. Programmers do it. System Administrators should too.
5. System Uptime is Top Priority - We, as System Administrators, may not like it but we have to admit that users, managers, and the public in general expect 100% uptime for any service or system. We also know that a system will fail at the most critical times.
Uptime is maximized by implementing good change control, timely security updates, and careful user management.
Realistically, one could list 20 or more critical things that System Administrators should know but after many years as a Linux and Unix Administrator, these are the ones that came to mind first.
What do you think are the most critical aspects of being a Linux System Administrator? Talk back and let me know.