B's IT Security - How to Hack Wifi Networks - Chapter 1 (Introduction & Network Basics)

I'm quite sure not the only one who was tagged as geek when I was a kid... but there was a trick what always provided more gratitude than anything else... I'd like to share this story...

So When I first turned up at a mate's with my laptop... instead of full with movies and games I was the wierdo - having a Linux on it, called Backtrack. I usually steered the conversation towards some topic what would require some googling (back in the day there were no smart phones.. ) asked for the wifi password, and popped the question, "Ohh.. you know what? .. I don't need your pw. I can crack your wifi" ... noone really believed me.. "Sure.. If you want to see it ..." than I just cracked it. Everyone was amazed, and I've gained some popularity.
Since than the technology changed a lot.  But this is how a Trick turned into a hobby than a profession.

Hey, Let's get Started!

1, What do we use? 

We use Linux!
Preferably Kali, But Ubuntu or any flavour is suitable if you can get hold of the aircrack-ng and the macchanger packages. With Kali it's installed on default, in any other options you have to install it manually.

sudo apt-get update
sudo apt-get install macchanger aircrack-ng

2, Network know-how (Boring but necessary)

What a network really is? - Bunch of connected devices to be able to transfer data and sharing resources between each-other.
By method you can have wired or wireless one, in terms of use makes no difference - transferring the same packages towards it's destination.

How your local networks works? You usually connect your device to a router / modem (later on Access Point or AP) what forwards your requests through the Internet Service Provider's (ISP's) network to it's destination.
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in a nutshell, for example you'd like to visit facebook.com, your PC send a request to your local network, the router/modem gets it on the ISP's network, and through the wide internet it reaches it's destination, facebook in response sends you the data, and it's traveling the same way back, till it reaches your PC and the page displays.

How it's been transferred? All the data, images, HTML code, CSS, Videos are broken down to small pieces packets. These Packets have a destination address, and circulating in the system until it's life expires or reaches it's destination.
In case of your local network using WIFI, all the packets are broadcasted in the air, so theoretically anyone in the range would be able capture and read them. (however all the packets are encrypted, so only the ones on the same network as you can decrypt them.)

Will be continued in the next Chapter!