Hacking WEP wifi passwordsBasic Entry into a WEP Encrypted Network
This Tutorial explains EVERYTHING in detail So, it is quite long.    Enjoy.
1.  Getting the right tools
This Tutorial is in Bt3 But Download The Latest Release Bt4.
Download Backtrack 4.  It can be found here:
http://www.backtrack-linux.org/downloads/I downloaded the Dvd iso and burned  it to a Dvd.  Insert your BT4  Dvd/usb drive and reboot your computer into  BT4.  I always load into  the 3rd boot option from the boot menu.   (VESA/KDE)  You only have a  few seconds before it auto-boots into the  1st option so be ready.  The  1st option boots too slowly or not at all  so always boot from the 2nd  or 3rd.  Experiment to see what works best  for you.
2. Preparing the slave network for attack
Once in BT4, click the tiny black box in the lower left corner to load   up a "Konsole" window.  Now we must prep your wireless card.
Type:
airmon-ng
You will see the name of your wireless card.  (mine is named "ath0")    From here on out, replace "ath0" with the name of your card.
Now type:
airmon-ng stop ath0
then type:
ifconfig wifi0 down
then:
macchanger --mac 00:11:22:33:44:55 wifi0
then:
airmon-ng start wifi0
What these steps did was to spoof (fake) your mac address so that JUST   IN CASE your computeris discovered by someone as you are breaking in,   they will not see your REAL mac address.  Moving on...
Now it's time to discover some networks to break into.
Type:
airodump-ng ath0
Now you will see a list of wireless networks start to populate.  Some   will have a better signal than others and it is a good idea to pick one   that has a decent signal otherwise it will take forever to crack or you   may not be able to crack it at all.
Once you see the network that you want to crack, do this:
hold down ctrl and type c
This will stop airodump from populating networks and will freeze the  screen so that you can see the info that you need.
**Now from here on out, when I tell you to type a command, you need to   replace whatever is in parenthesis with what I tell you to from your   screen.  For example: if i say to type:
-c (channel)
then dont actually type in
-c (channel)
Instead, replace that with whatever the channel number is...so, for  example you would type:
-c 6
Can't be much clearer than that...lets continue...
Now find the network that you want to crack and MAKE SURE that it says   the encryption for that network is WEP.  If it says WPA or any variation   of WPA then move on...you can still crack WPA with backtrack and some   other tools but it is a whole other ball game and you need to master  WEP  first.
![[Image: airodump.jpg]](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_s7Thjx7cfYliC-UQ2821X31Jh5ekf1mZIHhX-_M5yCbIAkLscdqO-ViHG-Fl46gwlkIn4OfXO-faYYt4v-SC63ZsV7yHYaDIQbrIPf6pp0KIddcF7db6paHnYQ6vVyJcB6=s0-d)
Once you've decided on a network, take note of its channel number and   bssid.  The bssid will look something like this -->    05:gk:30:fo:s9:2n
The Channel number will be under a heading that says "CH".
Now, in the same Konsole window, type:
airodump-ng -c (channel) -w (file name) --bssid (bssid) ath0
the FILE NAME can be whatever you want.  This is simply the place that   airodump is going to store the packets of info that you receive to later   crack.  You don't even put in an extension...just pick a random word   that you will remember.  I usually make mine "wepkey" because I can   always remember it.
**Side Note: if you crack more than one network in the same session, you   must have different file names for each one or it won't work.  I   usually just name them wepkey1, wepkey2, etc.
Once you typed in that last command, the screen of airodump will change   and start to show your computer gathering packets.  You will also see a   heading marked "IV" with a number underneath it.  This stands for   "Initialization Vector" but in noob terms all this means is "packets of   info that contain clues to the password."  Once you gain a minimum of   5,000 of these IV's, you can try to crack the password.  I've cracked   some right at 5,000 and others have taken over 60,000.  It just depends   on how long and difficult they made the password.
Now you are thinking, "I'm screwed because my IV's are going up really   slowly."  Well, don't worry, now we are going to trick the router into   giving us HUNDREDS of IV's per second.
3. Actually cracking the WEP password
Now leave this Konsole window up and running and open up a 2nd Konsole  window.  In this one type:
aireplay-ng -1 0  -a (bssid) -h 00:11:22:33:44:55 ath0
http://i574.photobucket.com/albums/ss184...eplay1.jpgThis will send some commands to the router that basically cause it to   associate with your computer even though you are not officially   connected with the password.  If this command is successful, you should   see about 4 lines of text print out with the last one saying something   similar to "Association Successful :-)"  If this happens, then good!    You are almost there.  Now type:
aireplay-ng -3 -b (bssid) -h 00:11:22:33:44:55 ath0
http://i574.photobucket.com/albums/ss184...eplay2.jpgThis will generate a bunch of text and then you will see a line where   your computer is gathering a bunch of packets and waiting on ARP and   ACK.  Don't worry about what these mean...just know that these are your   meal tickets.  Now you just sit and wait.  Once your computer finally   gathers an ARP request, it will send it back to the router and begin to   generate hundreds of ARP and ACK per second.  Sometimes this starts to   happen within seconds...sometimes you have to wait up to a few minutes.    Just be patient.  When it finally does happen, switch back to your   first Konsole window and you should see the number underneath the IV   starting to rise rapidly.  This is great!  It means you are almost   finished!  When this number reaches AT LEAST 5,000 then you can start   your password crack.  It will probably take more than this but I always   start my password cracking at 5,000 just in case they have a really  weak  password.
Now you need to open up a 3rd and final Konsole window.  This will be  where we actually crack the password.  Type:
aircrack-ng -b (bssid) (filename)-01.cap
Remember the filename you made up earlier?  Mine was "wepkey".  Don't   put a space in between it and -01.cap here.  Type it as you see it.  So   for me, I would type  wepkey-01.cap
Once you have done this you will see aircrack fire up and begin to crack   the password.  typically you have to wait for more like 10,000 to   20,000 IV's before it will crack.  If this is the case, aircrack will   test what you've got so far and then it will say something like "not   enough IV's.  Retry at 10,000."  DON'T DO ANYTHING!  It will stay   running...it is just letting you know that it is on pause until more   IV's are gathered.  Once you pass the 10,000 mark it will automatically   fire up again and try to crack it.  If this fails it will say "not   enough IV's.  Retry at 15,000." and so on until it finally gets it.
http://i574.photobucket.com/albums/ss184...crack1.jpgIf you do everything correctly up to this point, before too long you   will have the password!  now if the password looks goofy, dont worry, it   will still work.  some passwords are saved in ASCII format, in which   case, aircrack will show you exactly what characters they typed in for   their password.  Sometimes, though, the password is saved in HEX format   in which case the computer will show you the HEX encryption of the   password.  It doesn't matter either way, because you can type in either   one and it will connect you to the network.
Take note, though, that the password will always be displayed in   aircrack with a colon after every 2 characters.  So for instance if the   password was "secret", it would be displayed as:
se:cr:et
This would obviously be the ASCII format.  If it was a HEX encrypted   password that was something like "0FKW9427VF" then it would still   display as:
0F:KW:94:27:VF
Just omit the colons from the password, boot back into whatever   operating system you use, try to connect to the network and type in the   password without the colons and presto!  You are in!
It may seem like a lot to deal with if you have never done it, but after   a few successful attempts, you will get very quick with it.  If I am   near a WEP encrypted router with a good signal, I can often crack the   password in just a couple of minutes.
I am not responsible for what you do with this information.  Any   malicious/illegal activity that you do, falls completely on you   because...technically...this is just for you to test the security of   your own network.  :-)
I will gladly answer any legitimate questions anyone has to the best of  my ability.
HOWEVER, I WILL NOT ANSWER ANYONE THAT IS TOO LAZY TO READ THE WHOLE TUT   AND JUST ASKS ME SOME QUESTION THAT I CLEARLY ANSWERED.  No one wants   to hold your hand through this...read the tut and go experiment until   you get it right.
There are rare occasions where someone will use WEP encryption with SKA   as well.  (Shared Key Authentication)  If this is the case, additional   steps are needed to associate with the router and therefore, the steps I   lined out here will not work.  I've only seen this once or twice,   though, so you probably won't run into it.  If I get motivated, I may   throw up a tut on how to crack this in the future.
Hacking WEP wifi passwordsBy 
MamoOn,,