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OTUS(4) Device Drivers Manual OTUS(4)

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

otus* at uhub? port ?

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 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 (WPA-PSK and WPA2-PSK). WPA is the current encryption standard for wireless networks. It is strongly recommended that WEP not be used as the sole mechanism to secure wireless communication, due to serious weaknesses in it.

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

The driver needs at least version 1.0 of the following firmware files, which are loaded when an interface is attached:


Although these firmware files are freely redistributable, their usage is restricted. A prepackaged version of the firmware can be installed using fw_update(1).

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
NEC Aterm WL300NU-G
Netgear WNDA3100
Netgear WN111 v2
Planex GW-US300
TP-Link TL-WN821N v1, v2
Ubiquiti SR71 USB
Unex DNUA-81
Z-Com UB81
Z-Com UB82

The following example scans for available networks:

# ifconfig otus0 scan

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

nwid mynwid
wpakey mywpakey

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.

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

The otus driver first appeared in OpenBSD 4.6.

The otus driver was written by Damien Bergamini <> based on source code licensed under the ISC released in 2008 by Atheros Communications for Linux.

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) before those features can be supported.

July 12, 2017 OpenBSD-6.3