Wifi

References

• https://www.cyberciti.biz/tips/linux-find-out-wireless-network-speed-signal-strength.html

Commands

• iwconfig, get information or configure a wireless network interface

sudo iwconfig           # Get information
sudo iwconfig wlan0     # Configure

iwconfig
# # iwconfig
# lo        no wireless extensions.
# 
# eth0      no wireless extensions.
# 
# wlan0     IEEE 802.11abg  ESSID:off/any  
#           Mode:Managed  Access Point: Not-Associated   Tx-Power=15 dBm   
#           Retry  long limit:7   RTS thr:off   Fragment thr:off
#           Encryption key:off
#           Power Management:off

iwconfig wlan0         # Limit to wlan0

• iwlist, get more detailed wireless information from a wireless interface

sudo iwlist scan
sudo iw dev wlan0 scan   # wlan0 or wlp1s0 or ...

• rfkill, show state of RF SW/HW kill switch (WiFi / BT / ...)

rfkill list all

If using Network Manager:

nmcli connection show
# NAME                UUID                                  TYPE      DEVICE    
# testing             1eba2547-2cc2-4785-9288-f205aa6f533d  wifi      wlp1s0 
nmcli connection show "testing"
nmcli -f GENERAL,WIFI-PROPERTIES dev show wlp1s0

Utilities

Wavemon

See Linux commands.

Wifi PEAP

• Wifi PEAP at KULeuven

Linux Access Point

You can turn your laptop into a WiFi access point, provided of course that your WiFi card supports that feature:

sudo service network-manager stop
sudo iwconfig wlan0 mode master

If you get the following error then most probably it is not supported:

Error for wireless request "Set Mode" (8B06) : 
    SET failed on device wlan0 ; Invalid argument.

Turn NetworkManager back on:

sudo service network-manager start

Some links:

• MasterMode on Ubuntu Wiki
• WirelessAccessPoint on Ubuntu Wiki
• Building a Linux Wireless Access Point

Troubleshoot wifi

# Check device
lsusb                # if wifi usb device
lspci                # if wifi pci device
lspci | egrep -i 'wifi|wlan|wireless'

# Check if device has an interface
iwconfig

# Check status interfaces
ifconfig

# Check signal quality
sudo iwconfig wlp1s0|grep -i quality
# Link Quality=52/70  Signal level=-58 dBm  
nmcli dev wifi
# IN-USE  SSID           MODE   CHAN  RATE        SIGNAL  BARS  SECURITY 
#         testing        Infra  13    270 Mbit/s  70      ▂▄▆_  WPA2     
watch -n 1 cat /proc/net/wireless
# Inter-| sta-|   Quality        |   Discarded packets               | Missed | WE
#  face | tus | link level noise |  nwid  crypt   frag  retry   misc | beacon | 22
# wlp1s0: 0000   52.  -58.  -256        0      0      0      0    182        0

# Get available WiFi connections
nmcli c[onnection]

# Get Wifi Status
nmcli r[adio]

# If Wifi is down, turn it on:
nmcli r wifi on

Wifi is either controlled by NetworkManager or via the command line.

NetworkManager

Command file

• See file /etc/network/interfaces. See man page man interfaces
• For WPA, see file /etc/wpa_supplicant/wpa_supplicant.conf.

Miscellaneous

Wireless deauthentication code from [1]: About syslog wlan0: deauthenticated from 00:1d:7e:0c:24:5e (Reason: 14), see [2]: That means that the WPA encryption code is failing and the packet is corrupt. I would worry about that corrupt beacon from the AP. Troubleshooting WiFi (opensuse post) Getting info on WiFi (opensuse post)

3 Deauthenticated because sending station is leaving (or has left) IBSS or ESS. 14 MIC failure.

• See Common Issues