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airmon-ng

Airmon-ng

Description

This script can be used to enable monitor mode on wireless interfaces. It may also be used to go back from monitor mode to managed mode. Entering the airmon-ng command without parameters will show the interfaces status.

Usage

usage: airmon-ng <start|stop> <interface> [channel] or airmon-ng <check|check kill>

Where:

  • <start|stop> indicates if you wish to start or stop the interface. (Mandatory)
  • <interface> specifies the interface. (Mandatory)
  • [channel] optionally set the card to a specific channel.
  • <check|check kill> “check” will show any processes that might interfere with the aircrack-ng suite. It is strongly recommended that these processes be eliminated prior to using the aircrack-ng suite. “check kill” will check and kill off processes that might interfere with the aircrack-ng suite. For “check kill” see

Usage Examples

Typical Uses

To start wlan0 in monitor mode: airmon-ng start wlan0

To start wlan0 in monitor mode on channel 8: airmon-ng start wlan0 8

To stop wlan0: airmon-ng stop wlan0

To check the status: airmon-ng

Madwifi-ng driver monitor mode

This describes how to put your interface into monitor mode. After starting your computer, enter “iwconfig” to show you the current status of the wireless interfaces. It likely looks similar the following output.

Enter “iwconfig”:

 lo        no wireless extensions.
 
 eth0      no wireless extensions.
 
 wifi0     no wireless extensions.
 
 ath0      IEEE 802.11b  ESSID:""  Nickname:""
           Mode:Managed  Channel:0  Access Point: Not-Associated   
           Bit Rate:0 kb/s   Tx-Power:0 dBm   Sensitivity=0/3  
           Retry:off   RTS thr:off   Fragment thr:off
           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

If you want to use ath0 (which is already used):

airmon-ng stop ath0

And the system will respond:

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

Now, if you do “iwconfig”:

System responds:

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

You can see ath0 is gone.

To start ath0 in monitor mode: airmon-ng start wifi0

System responds:

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

Now enter “iwconfig”

System responds:

 lo        no wireless extensions.
 
 eth0      no wireless extensions.
 
 wifi0     no wireless extensions.
 
 ath0      IEEE 802.11g  ESSID:""  
        Mode:Monitor  Frequency:2.452 GHz  Access Point: 00:0F:B5:88:AC:82   
        Bit Rate=2 Mb/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=-96 dBm  Noise level=-96 dBm
        Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
        Tx excessive retries:0  Invalid misc:0   Missed beacon:0

You can see ath0 is in monitor mode. Also make sure the essid, nickname and encryption have not been set. The access point shows the MAC address of the card. The MAC address of the card is only shown when using the madwifi-ng driver. Other drivers do not show the MAC address of the card.

If ath1/ath2 etc. is running then stop them first prior to all the commands above:

 airmon-ng stop ath1

You can set the channel number by adding it to the end: airmon-ng start wifi0 9

mac80211 drivers monitor mode

See mac80211 versus ieee80211 stacks for some background information.

When using the mac80211 version of a driver, the use of airmon-ng and the aircrack-ng tools are slightly different.

Running:

 airmon-ng start wlan0

Gives something like:

 Interface   Chipset      Driver
 
 wlan0      Intel 4965 a/b/g/n   iwl4965 - [phy0]
          (monitor mode enabled on mon0)

Notice that it created “mon0”. You must then use “mon0” in all the subsequent aircrack-ng tools as the injection interface.

To remove monitor mode enter:

 airmon-ng stop mon0

Usage Tips

Confirming the Card is in Monitor Mode

To confirm that the card is in monitor mode, run the command “iwconfig”. You can then confirm the mode is “monitor” and the interface name.

For the madwifi-ng driver, the access point field from iwconfig shows your the MAC address of the wireless card.

Determining the Current Channel

To determine the current channel, enter “iwlist <interface name> channel”. If you will be working with a specific access point, then the current channel of the card should match that of the AP. In this case, it is a good idea to include the channel number when running the initial airmon-ng command.

BSSIDs with Spaces, Special Characters

See this FAQ entry on how to define your BSSID if it has spaces, quotes, double quotes or special characters in it.

How Do I Put My Card Back into Managed Mode?

It depends on which driver you are using. For all drivers except madwifi-ng:

airmon-ng stop <interface name>

For madwifi-ng, first stop ALL interfaces:

airmon-ng stop athX

Where X is 0, 1, 2 etc. Do a stop for each interface that iwconfig lists.

Then:

wlanconfig ath create wlandev wifi0 wlanmode sta

See madwifi-ng site documentation.

For mac80211 drivers, nothing has to be done, as airmon-ng keeps the managed interface alongside the monitor mode one (mac80211 uses interface types rather than modes of operation). If you no longer need the monitor interface and want to remove it, use the following:

airmon-ng stop monX

X is the monitor interface number - 0 unless you run multiple monitoring interfaces simultaneously.

Usage Troubleshooting

General

Quite often, the standard scripts on a linux distribution will setup ath0 and or additional athX interfaces. These must all be removed first per the instructions above. Another problem is that the script set fields such as essid, nickname and encryptions. Be sure these are all cleared.

Interface athX number rising (ath0, ath1, ath2.... ath45..)

The original problem description and solution can be found in this forum thread.

Problem: Every time the command “airmon-ng start wifi0 x” is run, a new interface is created as it should, but there where two problems. The first is that for each time airmon-ng is run on wifi0 the interface number on ath increases: the first time is ath1, the second ath2, the third ath3, and and so on. And this continues so in a short period of time it is up to ath56 and continuing to climb. Unloading the madwifi-ng driver, or rebooting the system has no effect, and the number of the interface created by airmon-ng continues to increase.

The second problem is that if you run airmon-ng on wifi0 the athXX created does not show as being shown as in Monitor mode, even though it is. This can be confirmed via iwconfig.

All these problem related to how udev assigns interface names. The answer is in this ticket: http://madwifi-project.org/ticket/972#comment:12 Thanks to lucida. The source of the problem comes from the udev persistent net rules generator.

Each distro is different… So here is a solution specifically for Gentoo. You should be able to adapt this solution to your particular distribution.

Gentoo 2.6.20-r4 Udev 104-r12 Madwifi 0.9.3-r2 Aircrack-ng 0.7-r2

Solution:

Change the file /etc/udev/rules.d/75-persistent-net-generator.rules

From: KERNEL==“eth*|ath*|wlan*|ra*|sta*…….. To: KERNEL==“eth*|Ath*|wlan*|ra*|sta*…….

In other words, you just capitalize the a. ath* becomes Ath*. Save the file.

Now delete the file /etc/udev/rules.d/70-persistent-net.rules.

Remove the driver and insert back.

Removing ath also works: KERNEL==“eth*|wlan*|ra*|sta*….

This is also on Gentoo, both 2.6.19-gentoo-r5 and 2.6.20-gentoo-r6

For Ubuntu, see this Forum posting. The modified version of /etc/udev/rules.d/75-persistent-net-generator.rules is:

 # these rules generate rules for persistent network device naming
 
 ACTION=="add", SUBSYSTEM=="net", KERNEL=="eth*|Ath*|wlan*|ra*|sta*" \
NAME!="?*", DRIVERS=="?*", GOTO="persistent_net_generator_do"
 
 GOTO="persistent_net_generator_end"
 LABEL="persistent_net_generator_do"
 
 # build device description string to add a comment the generated rule
 SUBSYSTEMS=="pci", ENV{COMMENT}="PCI device attr{vendor}:$attr{device}($attr{driver})"
 SUBSYSTEMS=="usb", ENV{COMMENT}="USB device 0x$attr{idVendor}:0x$attr{idProduct}($attr{driver})"
 SUBSYSTEMS=="ieee1394", ENV{COMMENT}="Firewire device $attr{host_id})"
 SUBSYSTEMS=="xen", ENV{COMMENT}="Xen virtual device"
 ENV{COMMENT}=="", ENV{COMMENT}="$env{SUBSYSTEM} device ($attr{driver})"
 
 IMPORT{program}="write_net_rules $attr{address}"
 
 ENV{INTERFACE_NEW}=="?*", NAME="$env{INTERFACE_NEW}"
 
 LABEL="persistent_net_generator_end"

Interface ath1 created instead of ath0

This troubleshooting tip applies to madwifi-ng drivers. First try stopping each VAP interface that is running (“airmon-ng stop IFACE” where IFACE is the VAP name). You can obtain the list from iwconfig. Then do “airmon-ng start wifi0”.

If this does not resolve the problem then follow the advice in this thread.

Why do I get ioctl(SIOCGIFINDEX) failed?

If you get error messages similar to:

  • Error message: “SIOCSIFFLAGS : No such file or directory”
  • Error message: “ioctl(SIOCGIFINDEX) failed: No such device”

Then See this FAQ entry.

Error message: "wlanconfig: command not found"

If you receive “wlanconfig: command not found” or similar then the wlanconfig command is missing from your system or is not in the the path. Use locate or find to determine if it is on your system and which directory it is in.

If it is missing from your system then make sure you have done a “make install” after compiling the madwifi-ng drivers. On Ubuntu, do “apt-get install madwifi-tools”.

If it is not in a directory in your path then move it there or add the directory to your path.

airmon-ng shows RT2500 instead of RT73

See this entry under installing the RT73 driver.

Error "add_iface: Permission denied"

You receive an error similar to:

 Interface       Chipset         Driver
 
 wlan0                   iwl4965 - [phy0]/usr/sbin/airmon-ng: line 338: /sys/class/ieee80211/phy0/add_iface: Permission denied
                               mon0: unknown interface: No matching device found
                               (monitor mode enabled on mon0)

or similar to this:

 wlan0   iwlagn - [phy0]/usr/local/sbin/airmon-ng: 856: cannot create /sys/class/ieee80211/phy0/add_iface: Directory nonexistent
 Error for wireless request "Set Mode" (8B06) :
  SET failed on device mon0 ; No such device.
 mon0: ERROR while getting interface flags: No such device

This means you have an old version of airmon-ng installed. Upgrade to at least v1.0-rc1. Preferably you should upgrade to the latest SVN version. See the installation page for more details. Also, don't forget you need to be root to use airmon-ng (or use sudo).

check kill fails

Distros from now on are going to adopt 'upstart' which is going to replace the /sbin/init daemon which manages services and tasks during boot.

Basically do:

 service network-manager stop
 service avahi-daemon stop
 service upstart-udev-bridge stop

and then proceed with greping and killing the pids of dhclient and wpa_supplicant.

This is the only way to kill ALL of the potentially problematic pids for aireplay-ng permanently. The trick is the kill the daemons first and then terminate the 'tasks'.

Source thread: http://forum.aircrack-ng.org/index.php?topic=6398.0 and http://forum.aircrack-ng.org/index.php?topic=8573

SIOCSIFFLAGS: Unknown error 132

If you have an output similar to:

# airmon-ng start wlan0
Interface	Chipset		Driver
wlan0		Broadcom	b43 - [phy0]SIOCSIFFLAGS: Unknown error 132
				(monitor mode enabled on mon0)

It indicates that RF are blocked. It needs to be enabled by using the switch on your laptop and/or using the following command:

rfkill unblock all

See also http://ubuntuforums.org/showthread.php?t=1311886

airmon-ng.txt · Last modified: 2010/10/31 16:25 by mister_x