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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 module is required by all native 802.11 drivers as well as
     the ndis(4) support.

     wlan supports multi-mode devices capable of operating in both 2.4GHz and
     5GHz bands and supports numerous 802.11 standards: 802.11a, 802.11b,
     802.11g, 802.11n, and 802.11s (Draft 3.0).  The WPA, 802.11i, and 802.1x
     security protocols are supported through a combination of in-kernel code
     and user-mode applications.  The WME/WMM multi-media protocols are
     supported entirely within the wlan module but require a suitably capable
     hardware device.  Likewise the 802.11h specification is supported only by
     suitably capable devices.

     Drivers provide 802.11 functionality through wlan interfaces that are
     created at runtime using interface cloning.  This is done with the
     ifconfig(8) create command or using the wlans_IFX variable in rc.conf(5).
     Some drivers support the creation of multiple wlan interfaces that share
     the same underlying device; this is the way by which ``multi-bss
     support'' is provided but it can also be used to create WDS links and
     other interesting applications.

     There are several types of wlan interfaces that may be created:

     sta      A client station in an infrastructure bss (i.e. one that
              associates to an access point).

     hostap   An access point in an infrastructure bss.

     mesh     A mesh station in an MBSS network.

     adhoc    A station in an IBSS network.

     ahdemo   A station operating in ``adhoc demo mode''.  This is essentially
              an IBSS station that does not use management frames (e.g. no
              beacons are transmitted).  An ahdemo interface is especially
              useful for applications that want to transmit and receive raw
              802.11 packets.

     monitor  An interface used exclusively for capturing 802.11 frames.  In
              particular this specified to have read-only properties which
              enables it to be operated on frequencies where one would
              otherwise not be allowed.

     wds      A station that passes 4-address 802.11 traffic for the purpose
              of tunneling traffic over a wireless link.  Typically this
              station would share the same MAC address as a hostap interface.
              It may be possible to create wds interfaces without a companion
              hostap interface but that is not guaranteed; one may need to
              create a hostap interface that does not send beacon frames
              before wds interfaces may be created.

     Note that an interface's type cannot be changed once it is created.

     wlan defines several mechanisms by which plugin modules may be used to
     extend its' functionality.  Cryptographic support such as WEP, TKIP, and
     AES-CCMP are implemented as standalone modules (if not statically
     configured into a system) that register with wlan.  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

     Debugging controls are available 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 access point.
     The wlandebug(8) tool provides a more user-friendly mechanism for doing
     the same thing.  Note that

           sysctl net.wlan.debug=mask

     defines the initial value of the debugging flags for each cloned wlan
     interface; this is useful to enable debug messages during interface
     creation.

COMPATIBILITY

     The module name of wlan was used to be compatible with NetBSD.

     Mesh stations follow the 802.11s Draft 3.0 specification which is not
     ratified and subject to change.  Beware that this specification is
     incompatible with earlier drafts; and stations implementing earlier
     drafts (e.g. Linux) may not interoperate.

SEE ALSO

     an(4), ath(4), bwi(4), ipw(4), iwi(4), iwn(4), malo(4), netintro(4),
     ral(4), rum(4), uath(4), upgt(4), ural(4), urtw(4), wi(4), wlan_acl(4),
     wlan_ccmp(4), wlan_tkip(4), wlan_wep(4), wlan_xauth(4), wpi(4), zyd(4)

STANDARDS

     More information can be found in the IEEE 802.11 Standards.

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, 802.11n, WPA/802.11i, WME,
     multi-bss, and add the extensible frameworks for cryptographic,
     authentication, and access control plugins.  This manual page was written
     by Tom Rhodes <trhodes@FreeBSD.org>.