Wi-Fi

To monitor data on the wifi network, install aircrack-ng, then run:

airomon-ng start wlan0
airodump-ng wlan0

You may get an error like:

[root@alarmpi ~]# airodump-ng wlan0
ioctl(SIOCSIWMODE) failed: Device or resource busy

ARP linktype is set to 1 (Ethernet) - expected ARPHRD_IEEE80211,
ARPHRD_IEEE80211_FULL or ARPHRD_IEEE80211_PRISM instead.  Make
sure RFMON is enabled: run 'airmon-ng start wlan0 <#>'
Sysfs injection support was not found either.

Make sure that the wireless device is in the monitor mode and then try again.

[root@alarmpi ~]# iwconfig wlan0
wlan0     IEEE 802.11bgn  ESSID:off/any
          Mode:Managed  Access Point: Not-Associated   Tx-Power=20 dBm
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off

[root@alarmpi ~]# ifconfig wlan0 down
[root@alarmpi ~]# iwconfig wlan0 mode monitor
[root@alarmpi ~]# ifconfig wlan0 up
[root@alarmpi ~]# iwconfig wlan0
wlan0     IEEE 802.11bgn  Mode:Monitor  Frequency:2.422 GHz  Tx-Power=20 dBm
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:off