Lab 1 - Selecting an OS

For the first lab we are going to select a distribution to work with. Some may think selecting a Linux distribution (operating system) would be easy, but in fact there are several hundred to choose from. So which is right for you?

The first question you have to ask yourself is, “what am I going to do with it?” This is a very important question because there are so many to pick from. If you’re just starting out and you’re not sure what you want yet, I would suggest looking at either Fedora or Ubuntu. These are two of the top distributions, and both have plenty of forms for help.

But before you download an iso (CD image file) and wipe Windows off your machine, you may want to play around with a live CD first. What’s a live CD you ask? A live CD is a full operating system on a CD-ROM!! All you have to do is to download an iso image, burn it to a CD, put the CD into your computer, and reboot. Like magic you’re running Linux in no time flat! (P.S. Fedora and Ubuntu come in Live CD’s).

Live CD’s are a great option because they give you a chance to try out different distributions without damaging your Windows operating system. Here is a great list of Linux Live CD’s.

So, for lab one, your task is to research the different Linux distributions you have to choose from and select one (or two, or three, etc). Once you do that, down load the iso files, burn your CD’s and start to explore.

(P.S. For more advanced users, you could also look into using VMware or VirtualBox to run your distribution of choice.)

For the labs we will be doing in this blog, I will be working with Fedora.

Host Firewall - Level 1

I know there are a ton of websites out there talking about firewalls, especially iptables, however I wanted to just take a minute to create a basic, but very functional firewall. So, here it is.

1) backup your current config file

sudo cp /etc/sysconfig/iptables /etc/sysconfig/iptables.orig

2) Edit the file /etc/sysconfig/iptables with your favorite editor (vi) and add the following lines

*filter
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -j DROP
COMMIT

3) Restart the iptables firewall

sudo service iptables restart

4) Enjoy

Note: This testing was done on CentOS 6.0

The History of Linux

So to get a better understanding of Linux let's start by examining where Linux comes from and why.

(Here's the short version)

In the early 70's there was UNIX. UNIX systems were not (and are still not) cheep and fall under a lot of the same licensing issues that a Microsoft box does. (i.e. you're not allowed to distribute or modify the code without their permission). So there was this guy by the name of Richard Stallman who came up with this idea to create an open source, freely distributed operating system. So in the 80's Richard started working on his "free" OS. At first he was the sole member of his team and began to write code and publish it on bulletin board systems (BBS). Soon Richard's team grew and he has people all over the place helping him write the code.

This was good news since building an operating system from scratch is no small task. If you've ever looked at building your own OS from the ground up, or even explored an OS in depth, you know there are a lot of moving parts that need to be taken into account. Things like the compiler, hardware support, libraries to support applications, text editors and tons of over things; oh, and don't forget about the kernel (you're going to need one of those).

So in 1985 Richard founded the "Free Software Foundation" to help with the GNU project. By 1990 Richard either found or had written most (if not all) of the components of the operating system; minus one, the kernel.

On a side note: coming up with the name for the project started one of the more odd phenomena in open source software; creating wired but meaningful names / acronyms for products. Richard came up with the acronym of GNU, which stands for "GNU's Not Unix". Yes, the G in GNU stands for GNU. This is known as a recursive acronym. Odd I know but people have been having fun with acronyms ever since.

Now back to our story. Around the same time the GNU project was being built, Linus Torvalds created a kernel (oddly enough, it was just what the GNU project needed). So joining Linus's kernel into the GNU project finished the puzzle and an open source, free operating system was born.

Going back to names for a second, since the OS is often referred to as Linux, most people think Linus created it. Of course he played a vital role in building it, but it's important to remember all the work the GNU team put into the OS as well. So to be correct, it should be referred to as "GNU/Linux".