wlan(4)

NAME

wlan - generic 802.11 link-layer support

SYNOPSIS

device wlan

DESCRIPTION

The wlan module provides generic code to support 802.11

drivers. Where a
device does not directly support 802.11 functionality this

layer fills
in. The wlan is required for the an(4), ath(4), awi(4),

ipw(4), iwi(4),
ral(4), ural(4), and wi(4) drivers, with other drivers to

follow.

The wlan module supports multi-mode devices capable of oper

ating in both
2.4GHz and 5GHz bands and supports numerous 802.11 proto

cols: 802.11a,
802.11b, and 802.11g. The WPA, 802.11i, and 802.1x security

protocols
are supported through a combination of in-kernel code and

user-mode
applications. The WME and WMM multi-media protocols are

supported
entirely within the wlan module but require a suitably capa

ble hardware
device.

The wlan module defines several mechanisms by which plugin

modules may be
used to extend functionality. Cryptographic support such as

WEP, TKIP,
and AES-CCMP are implemented as modules that are loaded on

demand (if not
statically configured into a system). Similarly there is an

authenticator framework for defining 802.11 authentication services

and a framework
for integrating access control mechanisms specific to the

802.11 protocol.

DEBUGGING

If the associated interface is marked for debugging with,

for example,

ifconfig wi0 debug

then messages describing the operation of the 802.11 proto

col will be
sent to the console. Complete debugging controls are avail

able using:

sysctl net.wlan.X.debug=mask

where X is the number of the wlan instance and mask is a

bit-or of control bits that determine which debugging messages to enable.

For example,

sysctl net.wlan.0.debug=0x00200000

enables debugging messages related to scanning for an access

point, adhoc
neighbor, or an unoccupied channel when operation as an ac

cess point.
The 80211debug tool provides a more user-friendly mechanism

for doing the
same thing.

Many drivers will also display the contents of each 802.11

frame sent and
received when the interface is marked with both debugging

and link2;
e.g.,

ifconfig wi0 debug link2

Beware however that some management frames may be processed

entirely
within the device and not be received by the host.

COMPATIBILITY

The module name of wlan was used to be compatible with NetB

SD.

SEE ALSO

an(4), ath(4), awi(4), ipw(4), iwi(4), netintro(4), ral(4),

ural(4),
wi(4), wlan_acl(4), wlan_ccmp(4), wlan_tkip(4), wlan_wep(4),
wlan_xauth(4)

STANDARDS

More information can be found in the IEEE 802.11 Standard.

HISTORY

The wlan driver first appeared in FreeBSD 5.0.

AUTHORS

Atsushi Onoe is the author of original NetBSD software from

which this
work began. Sam Leffler brought the code into FreeBSD and

then rewrote
it to support multi-mode devices, 802.11g, WPA/802.11i, WME,

and add the
extensible frameworks for cryptographic, authentication, and

access control plugins. This manual page was written by Tom Rhodes
<trhodes@FreeBSD.org>.

BSD November 26, 2005

BSD