low power wifi adapter tl-wn821n v6

[slavikfoxy]

I tested the driver for kali 2019 and 2021.3, the adapter produces 12 dBm, but on Ubuntu 2020 in the universal driver rtl8xxxu - 20 dBm, but the monitor mode does not work. Checked with the command iw dev.

┌──(root💀kali)-[~]
└─# iw dev
phy#2
Interface wlan0
ifindex 5
wdev 0x200000001
addr d0:37:45:c3:13:de
type monitor
txpower 12.00 dBm

iw list gives the following result:

┌──(root💀kali)-[~]
└─# iw list
Wiphy phy2
wiphy index: 2
max # scan SSIDs: 9
max scan IEs length: 2304 bytes
max # sched scan SSIDs: 0
max # match sets: 0
Retry short limit: 7
Retry long limit: 4
Coverage class: 0 (up to 0m)
Supported Ciphers:
* WEP40 (00-0f-ac:1)
* WEP104 (00-0f-ac:5)
* TKIP (00-0f-ac:2)
* CCMP-128 (00-0f-ac:4)
* CMAC (00-0f-ac:6)
Available Antennas: TX 0 RX 0
Supported interface modes:
* IBSS
* managed
* AP
* monitor
Band 1:
Capabilities: 0x1962
HT20/HT40
Static SM Power Save
RX HT20 SGI
RX HT40 SGI
RX STBC 1-stream
Max AMSDU length: 7935 bytes
DSSS/CCK HT40
Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
Minimum RX AMPDU time spacing: 16 usec (0x07)
HT Max RX data rate: 300 Mbps
HT TX/RX MCS rate indexes supported: 0-15
Bitrates (non-HT):
* 1.0 Mbps
* 2.0 Mbps
* 5.5 Mbps
* 11.0 Mbps
* 6.0 Mbps
* 9.0 Mbps
* 12.0 Mbps
* 18.0 Mbps
* 24.0 Mbps
* 36.0 Mbps
* 48.0 Mbps
* 54.0 Mbps
Frequencies:
* 2412 MHz [1] (20.0 dBm)
* 2417 MHz [2] (20.0 dBm)
* 2422 MHz [3] (20.0 dBm)
* 2427 MHz [4] (20.0 dBm)
* 2432 MHz [5] (20.0 dBm)
* 2437 MHz [6] (20.0 dBm)
* 2442 MHz [7] (20.0 dBm)
* 2447 MHz [8] (20.0 dBm)
* 2452 MHz [9] (20.0 dBm)
* 2457 MHz [10] (20.0 dBm)
* 2462 MHz [11] (20.0 dBm)
* 2467 MHz [12] (20.0 dBm)
* 2472 MHz [13] (20.0 dBm)
* 2484 MHz [14] (disabled)
Supported commands:
* new_interface
* set_interface
* new_key
* start_ap
* new_station
* set_bss
* join_ibss
* set_pmksa
* del_pmksa
* flush_pmksa
* remain_on_channel
* frame
* set_channel
* connect
* disconnect
WoWLAN support:
* wake up on anything (device continues operating normally)
software interface modes (can always be added):
* monitor
interface combinations are not supported
Device supports SAE with AUTHENTICATE command
Device supports scan flush.
max # scan plans: 1
max scan plan interval: -1
max scan plan iterations: 0
Supported TX frame types:
* IBSS: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* managed: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* AP: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* AP/VLAN: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* P2P-client: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
* P2P-GO: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
Supported RX frame types:
* IBSS: 0xd0
* managed: 0x40 0xb0 0xd0
* AP: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
* AP/VLAN: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
* P2P-client: 0x40 0xd0
* P2P-GO: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
Supported extended features:

┌──(root💀kali)-[~]
└─# uname -r
5.10.0-kali9-amd64

[clnhub]

I guess this is caused by power management. You can disable it, but it will probably only increase power usage, not the connection speed.

[albaluz35]

I found this in other p,lace, is it posible t merge this as a patch. If I just know how to do it, because this diver is based in a newer version...

Changing transmit power

Currently there is no way to change transmit power in the driver with iw or iwconfig tools, as you would with other wireless devices.
The values returned by these tools are purely fictional on this driver. However, you can still manually change the transmit power at compile time by editing the file hal/rl8192e/rtl8192e_phycfg.c and changing the lines below:

/* Manual Transmit Power Control
The following options take values from 0 to 63, where:
0 - disable
1 - lowest transmit power the device can do
63 - highest transmit power the device can do
Note that these options may override your country's regulations about transmit power.
Setting the device to work at higher transmit powers most of the time may cause premature
failure or damage by overheating. Make sure the device has enough airflow before you increase this.
It is currently unknown what these values translate to in dBm.
*/

// Transmit Power Boost
// This value is added to the device's calculation of transmit power index.
// Useful if you want to keep power usage low while still boosting/decreasing transmit power.
// Can take a negative value as well to reduce power.
// Zero disables it. Default: 2, for a tiny boost.
int transmit_power_boost = 2;
// (ADVANCED) To know what transmit powers this device decides to use dynamically, see:
// https://github.com/lwfinger/rtl8192ee/blob/42ad92dcc71cb15a62f8c39e50debe3a28566b5f/hal/phydm/rtl8192e/halhwimg8192e_rf.c#L1310

// Transmit Power Override
// This value completely overrides the driver's calculations and uses only one value for all transmissions.
// Zero disables it. Default: 0
int transmit_power_override = 0;

/* Manual Transmit Power Control */

---

Mange/rtl8192eu-linux-driver@89a8c35

https://github.com/Mange/rtl8192eu-linux-driver/blob/realtek-4.4.x/hal/rtl8192e/rtl8192e_phycfg.c