OpenBSD manual page server

Manual Page Search Parameters

MTW(4) Device Drivers Manual MTW(4)

mtwMediaTek USB IEEE 802.11b/g/n wireless network device

mtw* at uhub? port ?

The mtw driver supports USB 2.0 wireless adapters based on the MediaTek MT7601U chipset.

These are the modes the mtw driver can operate in:

BSS mode
Also known as mode, this is used when associating with an access point, through which all traffic passes. This mode is the default.
monitor mode
In this mode the driver is able to receive packets without associating with an access point. This disables the internal receive filter and enables the card to capture packets from networks which it wouldn't normally have access to, or to scan for access points.

The mtw driver can be configured to use Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA1 and WPA2). WPA2 is the current encryption standard for wireless networks. It is strongly recommended that neither WEP nor WPA1 are used as the sole mechanism to secure wireless communication, due to serious weaknesses. WPA1 is disabled by default and may be enabled using the option "wpaprotos wpa1,wpa2". For standard WPA networks which use pre-shared keys (PSK), keys are configured using the "wpakey" option. WPA-Enterprise networks require use of the wpa_supplicant package. The mtw driver offloads both encryption and decryption of data frames to the hardware for the WEP40, WEP104, TKIP(+MIC) and CCMP ciphers.

The mtw driver can be configured at runtime with ifconfig(8) or on boot with hostname.if(5).

The driver needs the following firmware files, which are loaded when an interface is brought up:


The following adapters should work:

D-Link DWA-127 rev B1
Edimax EW-7711UAn v2
Edimax EW-7711ULn v2
Foxconn WFU03
Tenda U2
Tenda W311MI v2
Yealink WF40

The following example scans for available networks:

# ifconfig mtw0 scan

The following hostname.if(5) example configures mtw0 to join network “mynwid”, using WPA key “mywpakey”, obtaining an IP address using DHCP:

join mynwid wpakey mywpakey
inet autoconf

mtw0: error N, could not read firmware ...
For some reason, the driver was unable to read the microcode file from the filesystem. The file might be missing or corrupted.
mtw0: could not load firmware
An error occurred while attempting to upload the microcode to the onboard 8051 microcontroller unit.
mtw0: device timeout
A frame dispatched to the hardware for transmission did not complete in time. The driver will reset the hardware. This should not happen.

arp(4), ifmedia(4), intro(4), netintro(4), usb(4), hostname.if(5), ifconfig(8)

The mtw driver first appeared in OpenBSD 7.1.

The mtw driver was written by James Hastings <> based on the run(4) driver by Damien Bergamini <>.

The mtw driver does not support any of the 802.11n capabilities offered by the MT7601U chipset. Additional work is required in ieee80211(9) before those features can be supported.

This driver does not support powersave mode.

December 24, 2021 OpenBSD-current