220 lines
6.4 KiB
Groff
220 lines
6.4 KiB
Groff
.\"
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.\" Copyright (c) 2003 Tom Rhodes
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 26, 2021
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.Dt WLAN 4
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.Os
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.Sh NAME
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.Nm wlan
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.Nd generic 802.11 link-layer support
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.Sh SYNOPSIS
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.Cd "device wlan"
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.Sh DESCRIPTION
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The
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.Nm
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module provides generic code to support 802.11 drivers.
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Where a device does not directly support 802.11 functionality
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this layer fills in.
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The
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.Nm
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module is required by all native 802.11 drivers.
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.Pp
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.Nm
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supports multi-mode devices capable of
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operating in both 2.4GHz and 5GHz bands and supports numerous
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802.11 standards: 802.11a, 802.11b, 802.11g, 802.11n, and 802.11s (Draft 3.0).
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The WPA, 802.11i, and 802.1x security protocols are supported
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through a combination of in-kernel code and user-mode applications.
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The WME/WMM multi-media protocols are supported entirely within
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the
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.Nm
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module but require a suitably capable hardware device.
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Likewise the 802.11h specification is supported only by suitably
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capable devices.
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.Pp
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Drivers provide 802.11 functionality through
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.Nm
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interfaces that are created at runtime using interface cloning.
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This is done with the
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.Xr ifconfig 8
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.Cm create
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command or using the
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.Va wlans_IFX
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variable in
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.Xr rc.conf 5 .
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Some drivers support the creation of multiple
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.Nm
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interfaces that share the same underlying device;
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this is the way by which ``multi-bss support'' is provided but it
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can also be used to create WDS links and other interesting applications.
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.Pp
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There are several types of
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.Nm
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interfaces that may be created:
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.Bl -tag -width monitor
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.It Cm sta
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A client station in an infrastructure bss
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(i.e. one that associates to an access point).
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.It Cm hostap
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An access point in an infrastructure bss.
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.It Cm mesh
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A mesh station in an MBSS network.
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.It Cm adhoc
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A station in an IBSS network.
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.It Cm ahdemo
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A station operating in ``adhoc demo mode''.
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This is essentially an IBSS station that does not use management
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frames (e.g. no beacons are transmitted).
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An
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.Cm ahdemo
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interface is especially useful for applications that want to transmit
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and receive raw 802.11 packets.
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.It Cm monitor
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An interface used exclusively for capturing 802.11 frames.
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In particular this specified to have read-only properties
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which enables it to be operated on frequencies where one
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would otherwise not be allowed.
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.It Cm wds
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A station that passes 4-address 802.11 traffic for the purpose
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of tunneling traffic over a wireless link.
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Typically this station would share the same MAC address as a
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.Cm hostap
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interface.
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It may be possible to create
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.Cm wds
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interfaces without a companion
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.Cm hostap
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interface but that is not guaranteed; one may need to create a
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.Cm hostap
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interface that does not send beacon frames before
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.Cm wds
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interfaces may be created.
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.El
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.Pp
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Note that an interface's type cannot be changed once it is created.
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.Pp
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.Nm
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defines several mechanisms by which plugin modules may
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be used to extend its functionality.
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Cryptographic support such as WEP, TKIP, and AES-CCMP are implemented
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as standalone modules (if not statically configured into a system)
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that register with
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.Nm .
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Similarly there is an authenticator framework for defining 802.11
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authentication services and a framework for integrating access
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control mechanisms specific to the 802.11 protocol.
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.Sh DEBUGGING
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If the
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.Dv IEEE80211_DEBUG
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option is included in the kernel configuration,
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debugging controls are available using:
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.Pp
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.Dl "sysctl net.wlan.X.debug=mask"
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.Pp
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where
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.Ar X
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is the number of the
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.Nm
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instance and mask is a bit-or of control bits that determine which
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debugging messages to enable.
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For example,
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.Pp
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.Dl "sysctl net.wlan.0.debug=0x00200000"
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.Pp
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enables debugging messages related to scanning for an access point,
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adhoc neighbor, or an unoccupied channel when operation as an access point.
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The
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.Xr wlandebug 8
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tool provides a more user-friendly mechanism for doing the same thing.
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Note that
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.Pp
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.Dl "sysctl net.wlan.debug=mask"
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.Pp
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defines the initial value of the debugging flags for each cloned
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.Nm
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interface; this is useful to enable debug messages during interface creation.
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.Sh COMPATIBILITY
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The module name of
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.Nm
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was used to be compatible with
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.Nx .
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.Pp
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Mesh stations follow the 802.11s Draft 3.0 specification which is
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not ratified and subject to change.
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Be aware that this specification is incompatible with earlier drafts.
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Stations implementing earlier drafts (e.g., Linux) may be incompatible.
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.Sh SEE ALSO
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.Xr an 4 ,
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.Xr ath 4 ,
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.Xr bwi 4 ,
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.Xr bwn 4 ,
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.Xr ipw 4 ,
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.Xr iwi 4 ,
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.Xr iwm 4 ,
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.Xr iwn 4 ,
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.Xr malo 4 ,
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.Xr mwl 4 ,
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.Xr netintro 4 ,
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.Xr otus 4 ,
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.Xr ral 4 ,
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.Xr rsu 4 ,
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.Xr rtwn 4 ,
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.Xr rum 4 ,
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.Xr run 4 ,
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.Xr uath 4 ,
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.Xr upgt 4 ,
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.Xr ural 4 ,
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.Xr urtw 4 ,
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.Xr wlan_acl 4 ,
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.Xr wlan_ccmp 4 ,
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.Xr wlan_tkip 4 ,
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.Xr wlan_wep 4 ,
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.Xr wlan_xauth 4 ,
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.Xr wpi 4 ,
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.Xr zyd 4
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.Sh STANDARDS
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More information can be found in the IEEE 802.11 Standards.
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 5.0 .
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.Sh AUTHORS
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Atsushi Onoe is the author of original
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.Nx
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software from which this work began.
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.An -nosplit
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.An Sam Leffler
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brought the code into
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.Fx
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and then rewrote it to support multi-mode devices,
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802.11g, 802.11n, WPA/802.11i, WME, multi-bss, and
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add the extensible frameworks
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for cryptographic, authentication, and access control plugins.
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This manual page was written by
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.An Tom Rhodes Aq Mt trhodes@FreeBSD.org .
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