Enable monitor mode in RTL8188CUS realtek wifi USB dongle

Question

I am trying to enable monitor mode in a RTL8188CUS dongle attached to a raspberryPI.

This is the error I get when I try to change the mode:

pi@raspberrypi ~ $ sudo iwconfig wlan0 mode monitor
Error for wireless request "Set Mode" (8B06) :
    SET failed on device wlan0 ; Invalid argument.

My questions:

A comment on this blog says that RTL8188CUS does not allow monitor mode. How can I be certain that the next cheap wifi dongle I buy for a RPI will work in monitor mode?
Is there any way I can make RTL8188CUS this work on RPI?
Can I sniff probe requests coming to the raspberryPI's wifi (I am running hostapd) without enabling monitor mode?

Details:

pi@raspberrypi ~ $ iwconfig wlan0
wlan0     unassociated  Nickname:"<WIFI@REALTEK>"
          Mode:Managed  Frequency=2.437 GHz  Access Point: Not-Associated
          Sensitivity:0/0
          Retry:off   RTS thr:off   Fragment thr: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

And

pi@raspberrypi ~ $ lsusb
Bus 001 Device 005: ID 0bda:8176 Realtek Semiconductor Corp. RTL8188CUS 802.11n WLAN Adapter

I have just run into this problem but just want to add that I tested this dongle on my desktop with full version of kali and it worked straight out of the box. For some reason it doesn't work on the pi though. — Syed Ali, Nov 17 '15 at 16:45
try this http://raspberrypi.stackexchange.com/questions/36747/enable-monitoring-mode-for-rtl8188cus-via-usb-on-raspbian — Syed Ali, Nov 19 '15 at 11:16

score 10 · Accepted Answer · edited Feb 14 '15 at 20:28

10

Counldn't fix the problem, I guess the chipset is not really supported.

Ordered an Ralink RT5370 from eBay for $5: Ralink RT5370 on eBay
(It has working monitor mode)

edited Feb 14 '15 at 20:28

Community

1

answered Jul 25 '13 at 19:22

zengr

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2
5
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1

Did that wifi adapter end up working for you out of the box on your pi or did you have to compile a different driver? – Scott Sep 29 '13 at 22:41
3

Ralink RT5370 worked out of the box. Followed this instruction to connect: https://www.modmypi.com/blog/how-to-set-up-the-ralink-rt5370-wifi-dongle-on-raspian – zengr Sep 30 '13 at 00:51

RolfBly · Answer 2 · 2017-06-12T05:25:44.317

In addition to @zengr's answer above, for those running into Device or resource busy when using this Ralink RT5370 dongle, i.e.:

~ $ sudo iwconfig wlan0 mode Monitor 
Error for wireless request "Set Mode" (8B06) :
    SET failed on device wlan0 ; Device or resource busy.

There is, PCMIIW, no generic way to find out which process is using device wlan0, but chances are it's ifplugd:

~ $ service ifplugd status
...
[...] wlan0: ifplugd process for device wlan0 running as pid 1234

~ $ sudo ifplugd -k -i wlan0            # kill ifplugd for wlan0
~ $ sudo ifconfig wlan0 down            # iFconfig 
~ $ sudo iwconfig wlan0 mode Monitor    # iWconfig
~ $ sudo ifconfig wlan0 up
~ $ iwconfig
wlan0     IEEE 802.11bgn  Mode:Monitor  Frequency:2.412 GHz  Tx-Power=20 dBm
      Retry short limit:7   RTS thr:off   Fragment thr:off
      Power Management:off

score 0 · Answer 3 · answered Sep 12 '19 at 16:10

There's project on GitHub that answers this problem without recompiling the kernel, https://github.com/TheN00bBuilder/rtl8188monitor

From the readme

Check the directory with the RTL8192CU drivers in them by typing sudo ls /lib/modules/$(uname -r)/kernel/drivers/net/wireless/realtek.

If it returns with an error or cannot find the driver (and it shouldn't), you will need to install the drivers that I have put on GitHub and follow the guide at this link. https://github.com/TheN00bBuilder/rtl8192drivers

Type sudo modprobe rtl8192cu to turn on the correct drivers, in case it is using the wrong ones.

Type the command ifconfig to list your wireless adaptors.

Note which wlan the Realtek adaptor is on.

Type sudo iw $WLAN interface add mon0 type monitor (where $WLAN is the interface from the previous step) to add a monitor mode function to the adaptor.

Don't type the pahrenthesis.

Try to start the monitor mode through airmon-ng with the command sudo airmon-ng start (wlan of Realtek adaptor).

If it fails with Error setting channel: command failed: Device or resource busy (-16), then run sudo airmon-ng check kill and try again.

That's it! Your RTL8188CUS should now work in monitor mode.

score 0 · Answer 4 · answered Sep 13 '19 at 07:56

Some years later the development has go on. Here are some up to date answers to the old questions:

A comment on this blog says that RTL8188CUS does not allow monitor mode. How can I be certain that the next cheap wifi dongle I buy for a RPI will work in monitor mode?

With iw list you may get something like this from my USB/wifi dongle:

rpi ~$ iw list
--- snip ---
Supported interface modes:
     * IBSS
     * managed
     * AP
     * AP/VLAN
     * monitor
     * mesh point
--- snip ---

As you can see here is the mode monitor listed. So you can be certain that your dongle supports this mode, otherwise it will not.

Is there any way I can make RTL8188CUS this work on RPI?

There is a project called nexmon that presents a driver to use monitor mode on the Raspberry Pi built-in WiFi device. I don't know if it also supports RTL8188CUS but using the on board WiFi may be an alternative. Look at nexmon.

Can I sniff probe requests coming to the raspberryPI's wifi (I am running hostapd) without enabling monitor mode?

No.

score 0 · Answer 5 · answered Jul 26 '13 at 15:34

You can know which functions are supported by looking up http://wireless.kernel.org/en/users/Drivers/ . My personal favourite is ath9k_htc (for USB) as I work mostly in IBSS mode (sometimes with WPA2 encryption too).

Of course as you see that information is not always up-to-date.

score -1 · Answer 6 · edited Jun 16 '20 at 10:47

-1

The USB dongle works just fine.

Just a thought, but there is a capitalization error. It should be:

sudo iwconfig wlan1 mode Monitor

not:

sudo iwconfig wlan1 mode monitor

add non-free firmware to repository list ( /etc/apt/sources.list ) Replacing squeeze with whichever version you are using (wheezy, jessy, sid...):

echo "deb http://ftp.us.debian.org/debian/ squeeze main non-free" >> /etc/apt/sources.list
echo "deb http://security.debian.org/ squeeze/updates main non-free" >> /etc/apt/sources.list
echo "deb http://ftp.us.debian.org/debian/ squeeze-updates main non-free" >> /etc/apt/sources.list
echo "deb http://backports.debian.org/debian-backports squeeze-backports main non-free" >> /etc/apt/sources.list

update and install and reboot (make sure dongle is plugged in):

sudo apt-get update
sudo apt-get update && sudo apt-get install firmware-realtek
sudo reboot

Then:

sudo ifconfig wlan1 down
sudo iwconfig wlan1 mode Monitor
sudo ifconfig wlan1 up

Output:

jmunsch@NE-522:~$ sudo ifconfig wlan1 up && dmesg | tail -n 4
[883636.004691] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cufw.bin
[883687.033184] rtl8192cu: MAC auto ON okay!
[883687.069050] rtl8192cu: Tx queue select: 0x05
[883687.070067] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cufw.bin
jmunsch@NE-522:~$ lsusb | tail -n 1 && iwconfig wlan1
Bus 002 Device 010: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]
wlan1     IEEE 802.11bgn  Mode:Monitor  Tx-Power=20 dBm

          Retry  long limit:7   RTS thr=2347 B   Fragment thr:off
          Power Management:off

See Here for Details/Source Code/TarBalls:

edited Jun 16 '20 at 10:47

Community

1

answered Jun 20 '14 at 04:08

jmunsch

99
3

This fails to work on a RTL8188eu with device id 0bda:8179. – Colin Dean Dec 28 '14 at 02:12
It seems that the firmware repository list is out of date. Where can I find the updated links? – Brannon Jan 04 '15 at 21:23
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@Brannon I updated my answer at the bottom, with a link to the package page for the non-free realtek-firmware also consider: https://github.com/lwfinger/rtl8188eu – jmunsch Jan 06 '15 at 11:40
I have exactly the same deviceid in lsusb output as yours, made all the steps you mentioned, compiled drivers from the link and still I'm seeing the error zengr experienced: "Error for wireless request "Set Mode" (8B06)" – Alexey Jun 09 '15 at 06:38
you down, monitor and up wlan0 but then ifconfig wlan1. Typo? – der_michael Sep 29 '16 at 21:36
@der_michael yep updated. – jmunsch Sep 29 '16 at 22:54
Two serious caveats here. (1) This did not work with Edimax/Realtek RTL8188CUS device ID 7392:7811. (2) Adding Debian links to sources.list for Raspbian is a recipe for problems. sudo apt-get upgrade left me with Samba FUBAR. Fixing that is a pain. I ended up restoring a recent drive image back to SD-card. – RolfBly Apr 14 '17 at 11:00

Enable monitor mode in RTL8188CUS realtek wifi USB dongle

6 Answers6

The USB dongle works just fine.

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