BackTrack - Testing Wireless Network Security: Secure your wireless networks against attacks, hacks, and intruders with this step-by-step guide

There are a number of factors to consider when we work with a wireless card in Linux, and the most important one is to know what the chipset of our wireless card is. This is because we have to know whether we have a driver to support the card, and it takes work to determine what that chipset is. The challenging cards are normally the ones that are built into laptops; in most cases, this card will not work in BackTrack without doing some work and spending some time on it.

The first place to look for information, whether or not your card will work, is on the BackTrack website. There is a listing of supported cards on the BackTrack website at http://www.BackTrack-linux.org/wiki/index.php/Wireless_Drivers. The site is shown in the next screenshot:

Getting a wireless card to work can be a challenging process, and it is often time-consuming. However, there are times when you do get lucky and the card is recognized at boot, but more often than not, it takes additional...

Now that we have the Gnome desktop started, the next thing we will do is open a terminal window. You can do this by clicking on the shortcut icon, or go the long way by navigating to Application | Accessories | Terminal. The result is that a terminal window opens. In this terminal window, enter the dmesg command.

root@bt:~# dmesg

The result of this command will make you scroll your screen a lot. The dmesg command displays the contents of the ring buffer. Do not worry if you do not know what a buffer is, just think of it as a place used to store data. This ring buffer that is displayed contains the messages that the system displays as it reads and encounters the hardware and devices of your machine. To scroll up and view this would be a bit of a challenge, but the one thing to remember about Linux is that they have devised ways for us to do this much more efficiently. The first method we will look at is the more option; enter the following...

The next thing we want to do is to look at the iwconfig tool. In your terminal window, enter iwconfig:

root@bt:~# iwconfig

A sample output of this command is shown in the following screenshot; it shows that there are no wireless cards currently recognized on this machine.

At this time, you are probably wondering what we have to do to get the card recognized? Unfortunately, if the card is not one among those that are recommended, it can become a daunting task. So, we will try a few more things before we reveal the guaranteed way to get a wireless card that we know will work within the BackTrack distribution.

When you are in a virtual environment, you can see whether the device is listed or just not connected. We do this by clicking on Removable Devices under the VM menu. This will bring up a list of removable devices found on the machine, which is displayed in the following screenshot:

The process now is to connect each device by selecting the available...

I am sure there are some of you who still want to try and get your card working, so we have a few more steps you can try, and we will cover them now. Having said that, it is highly recommended that you use one of the two cards mentioned earlier.

The next thing to try is the airmon-ng command. There is very little chance that your card will be here when it is nowhere else, but we can never say never, because this is electronics! In your terminal window, enter airmon-ng., using the following command:

root@bt:~# airmon-ng

The output of this command is shown in the next screenshot:

Once again we have failed! The card is not recognized, so now it is a matter of searching the Internet and trying to find a fix to get your card working. One alternative is to use any external card you may have. If you have an external card, plug it in and go through the same steps as before. There are two places to go to try and read more about getting your card operational. They are http...

At this point, it is important that we establish what we want to accomplish with the BackTrack tool. We really are not interested in using the wireless card to connect to an access point, because what we want to do is to use the card differently. When you connect a wireless card to an access point, you are using one of the modes of the card. That mode is the managed mode, which is the mode that the card is in, as shown earlier. When you want to analyze network traffic (or "sniff", as it is commonly referred to), you put the card in a promiscuous mode. With our wireless cards, we do not call the mode promiscuous; we instead call it the monitor mode. The best way to put a card into the monitor mode is to use a tool, and we will do that in a moment. First off, we will see how to use the BackTrack card to connect to the network, just in case at times you want to be able to do this.

The tool we will use now is the one that is GUI-based. We could do the entire configuration...

It is disturbing that we continue to see networks using the Wired Equivalent Privacy (WEP) algorithm. We will get into the weaknesses of WEP and show how easy it is to obtain the WEP key for an attacker and also for you if you are working with your own network or have written the authorization to test someone else's network. There is absolutely no reason you or anyone else should be using WEP to protect a wireless network. Now that you know how to get your card to work, you can click on a network and connect to it if you like by clicking on the Connect button. An example of a connection to the WoodTigerLili network is shown in the following screenshot:

Once we are connected, we can treat this like any other wireless connection. You can verify that it is connected by entering the ifconfig wlan0 command in a terminal window:

root@bt:~# ifconfig wlan0

The output of a connected adapter is shown in the next screenshot:

As you may have noticed, this is just...

This concludes the chapter. In this chapter, we got to experiment with getting your wireless card working in BackTrack; as you discovered, it is no small task. We also saw the recommendation that you make a small investment and get one of the cards that is supported by BackTrack. We saw two USB cards, Wi-Fire and Alpha. Either of these cards will allow you to use the full power of the BackTrack tools. In the next chapter, we will look at how to use the tools to explore the wireless zones around you.