---
name: "mtw"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/mtw"
---

# mtw(4)

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

## NAME

**mtw** – MediaTek USB IEEE 802.11b/g/n wireless network device

## SYNOPSIS

**mtw\* at uhub? port ?**

## DESCRIPTION

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 *infrastructure* 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 currently the most secure encryption standard for wireless networks supported by OpenBSD. 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)](/ifconfig/8.md) or on boot with [hostname.if(5)](/hostname.if/5.md).

## FILES

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

- /etc/firmware/mtw-mt7601u

  ## HARDWARE

The following adapters should work:

- ASUS USB-N10 v2

  - D-Link DWA-127 rev B1

  - Edimax EW-7711UAn v2

  - Edimax EW-7711ULn v2

  - Foxconn WFU03

  - Tenda U2

  - Tenda W311MI v2

  - TP-LINK TL-WN727N v4

  - Yealink WF40

  ## EXAMPLES

The following example scans for available networks:

```
# ifconfig mtw0 scan
```

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

```
join mynwid wpakey mywpakey
inet autoconf
```

## DIAGNOSTICS

- 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.

## SEE ALSO

[arp(4)](/arp/4.md), [ifmedia(4)](/ifmedia/4.md), [intro(4)](/intro/4.md), [netintro(4)](/netintro/4.md), [usb(4)](/usb/4.md), [hostname.if(5)](/hostname.if/5.md), [ifconfig(8)](/ifconfig/8.md)

## HISTORY

The **mtw** driver first appeared in OpenBSD 7.1.

## AUTHORS

The **mtw** driver was written by James Hastings ⟨*hastings@openbsd.org*⟩ based on the [run(4)](/run/4.md) driver by Damien Bergamini ⟨*damien.bergamini@free.fr*⟩.

## CAVEATS

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