BWI(4)

NAME
bwi - Broadcom AirForce IEEE 802.11b/g wireless network device

SYNOPSIS
bwi* at cardbus?
bwi* at pci?

DESCRIPTION
The bwi driver provides support for Broadcom AirForce based PCI/Cardbus network adapters.

These are the modes the bwi 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 bwi 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 bwi driver relies on the software 802.11 stack for both encryption and decryption of data frames.

The transmit speed is user-selectable or can be adapted automatically by the driver depending on the received signal strength and on the number of hardware transmission retries.

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

FILES
The driver needs a firmware file which is loaded when an interface is brought up:

/etc/firmware/bwi-airforce

A prepackaged version of the firmware can be installed using fw_update(8).

HARDWARE
The following cards are among those supported by the bwi driver:
Card | Chip | Bus | Standard
Apple Airport Extreme | BCM4306 | PCI | b/g
Apple Airport Extreme | BCM4318 | PCI | b/g
ASUS WL-138g | BCM4318 | PCI | b/g
Buffalo WLI-CB-G54 | BCM4306 | CardBus | b/g
Compaq R4035 onboard | BCM4306 | PCI | b/g
HP nx6125 | BCM4319 | PCI | b/g
Linksys WPC54G Ver 3 | BCM4318 | CardBus | b/g
Linksys WPC54GS Ver 2 | BCM4318 | CardBus | b/g
TRENDnet TEW-401PCplus | BCM4306 | CardBus | b/g
US Robotics 5411 | BCM4318 | CardBus | b/g

EXAMPLES
The following example scans for available networks:

    # ifconfig bwi0 scan

The following hostname.if(5) example configures bwi0 to join network “mynwid”, using WPA key “mywpakey”, obtaining an IP address using DHCP:

    join mynwid wpakey mywpakey
    inet autoconf

SEE ALSO
arp(4), cardbus(4), ifmedia(4), intro(4), netintro(4), pci(4), hostname.if(5), ifconfig(8)

HISTORY
The bwi driver first appeared in OpenBSD 4.3.

AUTHORS
-nosplit The bwi driver was written for DragonFly by Sepherosa Ziehau and ported to OpenBSD by Jonathan Gray and Marcus Glocker.

CAVEATS
Some chips are incorrectly calibrated due to the lack of documentation, which can slow the amount of traffic to the point of being unusable. Furthermore this driver only supports firmware version 3.

The BCM4331 chip isn't supported by this driver but the driver disables the chip if detected, since some buggy EFI revisions found in 2011-2012 Macs leave the chip enabled, causing it to emit spurious interrupts when the shared interrupt line is enabled.