---
name: "otus"
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/otus"
---

# otus(4)

Atheros USB IEEE 802.11a/b/g/n wireless network device

## NAME

**otus** – Atheros USB IEEE 802.11a/b/g/n wireless network device

## SYNOPSIS

**otus\* at uhub? port ?**

## DESCRIPTION

The **otus** driver supports USB 2.0 wireless network devices based on Atheros Communications AR9001U chipset.

The AR9001U chipset is made of an AR9170 MAC/Baseband and an AR9101 (1T2R), AR9102 (2T2R) or AR9104 (dual-band 2T2R) Radio.

These are the modes the **otus** 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 **otus** 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. "**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 **otus** 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 at least version 1.0 of the following firmware files, which are loaded when an interface is attached:

- */etc/firmware/otus-init*

  - */etc/firmware/otus-main*

  Although these firmware files are freely redistributable, their usage is restricted. A prepackaged version of the firmware can be installed using [fw\_update(8)](/fw_update/8.md).

## HARDWARE

The following adapters should work:

- 3Com 3CRUSBN275

  - Arcadyan WN7512

  - CACE AirPcap Nx

  - D-Link DWA-130 rev D1

  - D-Link DWA-160 rev A1

  - D-Link DWA-160 rev A2

  - IO-Data WN-GDN/US2

  - NEC Aterm WL300NU-G

  - Netgear WNDA3100

  - Netgear WN111 v2

  - Planex GW-US300

  - SMC Networks SMCWUSB-N2

  - TP-Link TL-WN821N v1, v2

  - Ubiquiti SR71 USB

  - Unex DNUA-81

  - Z-Com UB81

  - Z-Com UB82

  - ZyXEL NWD-271N

  ## EXAMPLES

The following example scans for available networks:

```
# ifconfig otus0 scan
```

The following [hostname.if(5)](/hostname.if/5.md) example configures otus0 to join network “mynwid”, using WPA key “mywpakey”, obtaining an IP address using DHCP:

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

## DIAGNOSTICS

- otus0: 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.

- otus0: 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 **otus** driver first appeared in OpenBSD 4.6.

## AUTHORS

The **otus** driver was written by Damien Bergamini ⟨*damien.bergamini@free.fr*⟩ based on source code licensed under the ISC released in 2008 by Atheros Communications for Linux.

## CAVEATS

The AVM FRITZ!WLAN USB Stick N adapter is currently not supported.

The **otus** driver does not support any of the 802.11n capabilities offered by the AR9001U chipset. Additional work is required in [ieee80211(9)](/ieee80211/9.md) before those features can be supported.