Sven-Erik Zetterström - Cantenna the Poor Wifi Hackers Choice

Dedicated to a group thats still meant something, long after its gone

.. Shoot me again I ain't dead yet

Shoot me again

All these shots I take

I spit back at you

All the shit you fake

Comes back to haunt you

All the shots..

All the shots I take

What difference did I make?

All the shots I take

I spit right back at you ..

Copyright 2016 by Sven-Erik Zetterstrm

All rights reserved This book or any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of the publisher except for the use of brief quotations in a book review or scholarly journal

First printing 2016

ISBN: 978-1-365-46393-8

Sven-Erik Zetterstrm

Please note:

Never do anything against another wireless network without the owners written approval. This book is NOT an invitation for you to commit crimes, therefore its in your interest to check with your countrys laws what applicable. It is not illegal to own a Cantenna or build one, but if you get caught doing illegal activities, you're going to get fines for using the antenna in addition to your other charges, IF they can prove that your antenna interferes with other licensed frequencies.

Since I finished my last book (Basic Wifi-Hacking) people have asked me about one of my last chapter in the previous book, about how to build and how to use a cantenna. Some have even asked if the last part could be fitted in a separate book, so I thought about it for a while and I had the extra time to do so, but Im sorry it took so long. I also added some extra information to it as well. The plan for this small book is to be a cheap and informative book with all information converted to the metric scale. Also this book has nothing to do with hacking. You do not need to be handy like a craftsman, but you should at least know which end on a screwdriver to use.

This is one of my projects I decided to translate and rewrite in this book I will go over some very basic theory, and how to build it, and include some testing with it in a line of sight with as few interference as possible. Why I include this in the book is simple, I want that the masses that read this book should be able to get a stronger antenna without ruining them, and a cantenna is a cheap street smart way to get some good results. Its interesting though, how a simple thing as a can could be helpful to get a better reception on your network Antennas today arent that expensive, but I bet you none of them is as cheap as this. This is the poor WiFi-hackers choice. Its normally small, and somewhat strong, around 7-10dBi, and its a directional antenna. The price to make one seldom exceed $7. You can easy make it longer by buying a longer can or perhaps use a welding machine and an aluminum tube as I have done. There are both pros and cons with a long antenna, as I will talk about later.

Important Info!! To use a Cantenna of this type thats described in this book its required that your WiFi USB stick / WiFi-card has an external antenna with an R-SMA connector, so you can replace the antenna with an pigtail.

The most expensive part is the N-connector thats around $3. The can of course, nuts and bolts doesnt cost many cents and the 2mm copper wire you can get for free, just ask any electrical store if they have a 5cm leftover cable that you can have.

In this test Im using the Pringels can, that works, but its far from optimal, it sucks to be frankly but it works. If I wanted to choose I will go for something like Nallys Big Chunk Chili can or similar

You will come a long way by not going in depth and rely on a couple of simple rules. The idea is to show you how to build the antenna and show some performance in a LOS (line of sight) and test it for you guys in different distances.

First we have to decide what a Cantenna really is.. You can hear it by the name, "Cantenna" comes from the word "Can antenna" which is a good explanation of what we are doing. We are building a WiFi antenna from a can!

In an ordinary antenna construction, it is important to get the right feed with the correct impedance! (Usually 50 or 100ohm) but we will not have this problem with this model of antenna. Imagine a bottle and you blowing in it to get a tone. It is like a church organ. With the right distance away from the bottom and the right length of the dipole you will get your tone. The Ting we intend to blow with in this case is a dipole, or a thick 1,8-2mm copper cable, called a waveguide

There are many different types of waveguide antennas out there, the problem with most of them is that you need a welding-machine, and more equipment but the best part is that those are way stronger than the cantenna. Im talking about the "slotted waveguide antennas estimated performance is approximately 16-18dBi. I must also mention the Bi-Quad antenna as well. I might cover the BI-quad antenna in a different book. You can use it with a satellite dish, but it work well just as it is. Effect without the sat disk 12-16dBi. All of these antennas are easy to build, and easy to understand, however I believe that the cantenna are the most easiest to build.

So I have used the cantenna for many years. I have used it in my war-driving days and you know, things happens and you buy stronger, better and more reliable antennas and things as this just take up unnecessary place in my brain, so I thought about sharing

It was not long before the track led me into a closet that should remain closed. I realized pretty quickly that this type of antennas are highly prized in the WiFi hacker circles, just because its small, easy to build and strong, but that does not sit equally well by the FCC (Federal Communications Commission), and the Swedish equivalent PTS (Post and Tele Styrelsen) It is not illegal to own or use a Cantenna (in Sweden) but they don't like you to use them, and if you use it to hack your way into someone's network without permission from the owner, and you get caught you're going to get fines for using the antenna in addition to your other charges, if they can prove that your antenna interferes with other licensed frequencies

The purpose of this section of the book is to show how to build an antenna and how powerful they are. I had intended from the beginning just build an antenna, but it gets two. I want to check and compare a pringels can against another more professional that I built entirely of aluminum. The pringels can / tin-can is most common in hacking spheres, and I want to compare how much difference there is between these two.

So one of the cantenna is built of a pringels can, the other one is built of thicker aluminum tubing. Why I chose a pringels can is to the inside of this is covered with a thin aluminum foil, cheap to buy and the bottom is made of aluminum. The thin aluminum foil in the cardboard tube is enough for it to be used as an antenna. The phenomenon is called the "skin effect" and is the current that the electromagnetic oscillation we call radio waves generates, which is gaining more superficial in a metal the higher the frequency is. It is therefore important that the surface leads well and is not corroded or full of dust etc, depending on the material that leads, best had been the gold of course, after silver copper and aluminum but tin and plate works as well.