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一个Linux下无线网卡的设置工具

WPA Supplicant
==============

Copyright (c) 2003-2006, Jouni Malinen <[e-mail]> and
contributors
All Rights Reserved.

This program is dual-licensed under both the GPL version 2 and BSD
license. Either license may be used at your option.



License
-------

GPL v2:

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

(this copy of the license is in COPYING file)


Alternatively, this software may be distributed under the terms of BSD
license:

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

3. Neither the name(s) of the above-listed copyright holder(s) nor the
   names of its contributors may be used to endorse or promote products
   derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.



Features
--------

Supported WPA/IEEE 802.11i features:
- WPA-PSK ("WPA-Personal")
- WPA with EAP (e.g., with RADIUS authentication server) ("WPA-Enterprise")
  Following authentication methods are supported with an integrate IEEE 802.1X
  Supplicant:
  * EAP-TLS
  * EAP-PEAP/MSCHAPv2 (both PEAPv0 and PEAPv1)
  * EAP-PEAP/TLS (both PEAPv0 and PEAPv1)
  * EAP-PEAP/GTC (both PEAPv0 and PEAPv1)
  * EAP-PEAP/OTP (both PEAPv0 and PEAPv1)
  * EAP-PEAP/MD5-Challenge (both PEAPv0 and PEAPv1)
  * EAP-TTLS/EAP-MD5-Challenge
  * EAP-TTLS/EAP-GTC
  * EAP-TTLS/EAP-OTP
  * EAP-TTLS/EAP-MSCHAPv2
  * EAP-TTLS/EAP-TLS
  * EAP-TTLS/MSCHAPv2
  * EAP-TTLS/MSCHAP
  * EAP-TTLS/PAP
  * EAP-TTLS/CHAP
  * EAP-SIM
  * EAP-AKA
  * EAP-PSK
  * EAP-PAX
  * LEAP (note: requires special support from the driver for IEEE 802.11
	  authentication)
  (following methods are supported, but since they do not generate keying
   material, they cannot be used with WPA or IEEE 802.1X WEP keying)
  * EAP-MD5-Challenge 
  * EAP-MSCHAPv2
  * EAP-GTC
  * EAP-OTP
- key management for CCMP, TKIP, WEP104, WEP40
- RSN/WPA2 (IEEE 802.11i)
  * pre-authentication
  * PMKSA caching



Requirements
------------

Current hardware/software requirements:
- Linux kernel 2.4.x or 2.6.x with Linux Wireless Extensions v15 or newer
- FreeBSD 6-CURRENT
- NetBSD-current
- Microsoft Windows with WinPcap (at least WinXP, may work with other versions)
- drivers:
	Host AP driver for Prism2/2.5/3 (development snapshot/v0.2.x)
	(http://hostap.epitest.fi/)
	Driver need to be set in Managed mode ('iwconfig wlan0 mode managed').
	Please note that station firmware version needs to be 1.7.0 or newer
	to work in WPA mode.

	Linuxant DriverLoader (http://www.linuxant.com/driverloader/)
	with Windows NDIS driver for your wlan card supporting WPA.

	Agere Systems Inc. Linux Driver
	(http://www.agere.com/support/drivers/)
	Please note that the driver interface file (driver_hermes.c) and
	hardware specific include files are not included in the
	wpa_supplicant distribution. You will need to copy these from the
	source package of the Agere driver.

	madwifi driver for cards based on Atheros chip set (ar521x)
	(http://sourceforge.net/projects/madwifi/)
	Please note that you will need to modify the wpa_supplicant .config
	file to use the correct path for the madwifi driver root directory
	(CFLAGS += -I../madwifi/wpa line in example defconfig).

	ATMEL AT76C5XXx driver for USB and PCMCIA cards
	(http://atmelwlandriver.sourceforge.net/).

	Linux ndiswrapper (http://ndiswrapper.sourceforge.net/) with
	Windows NDIS driver.

	Broadcom wl.o driver
	This is a generic Linux driver for Broadcom IEEE 802.11a/g cards.
	However, it is proprietary driver that is not publicly available
	except for couple of exceptions, mainly Broadcom-based APs/wireless
	routers that use Linux. The driver binary can be downloaded, e.g.,
	from Linksys support site (http://www.linksys.com/support/gpl.asp)
	for Linksys WRT54G. The GPL tarball includes cross-compiler and
	the needed header file, wlioctl.h, for compiling wpa_supplicant.
	This driver support in wpa_supplicant is expected to work also with
	other devices based on Broadcom driver (assuming the driver includes
	client mode support).

	Intel ipw2100 driver
	(http://sourceforge.net/projects/ipw2100/)

	Intel ipw2200 driver
	(http://sourceforge.net/projects/ipw2200/)

	In theory, any driver that supports Linux wireless extensions can be
	used with IEEE 802.1X (i.e., not WPA) when using ap_scan=0 option in
	configuration file.

	Wired Ethernet drivers (with ap_scan=0)

	BSD net80211 layer (e.g., Atheros driver)
	At the moment, this is for FreeBSD 6-CURRENT branch and NetBSD-current.

	Windows NDIS
	The current Windows port requires WinPcap (http://winpcap.polito.it/).
	See README-Windows.txt for more information.

wpa_supplicant was designed to be portable for different drivers and
operating systems. Hopefully, support for more wlan cards and OSes will be
added in the future. See developer's documentation
(http://hostap.epitest.fi/wpa_supplicant/devel/) for more information about the
design of wpa_supplicant and porting to other drivers. One main goal
is to add full WPA/WPA2 support to Linux wireless extensions to allow
new drivers to be supported without having to implement new
driver-specific interface code in wpa_supplicant.

Optional libraries for layer2 packet processing:
- libpcap (tested with 0.7.2, most relatively recent versions assumed to work,
	this is likely to be available with most distributions,
	http://tcpdump.org/)
- libdnet (tested with v1.4, most versions assumed to work,
	http://libdnet.sourceforge.net/)

These libraries are _not_ used in the default Linux build. Instead,
internal Linux specific implementation is used. libpcap/libdnet are
more portable and they can be used by adding CONFIG_DNET_PCAP=y into
.config. They may also be selected automatically for other operating
systems.


Optional libraries for EAP-TLS, EAP-PEAP, and EAP-TTLS:
- openssl (tested with 0.9.7c and 0.9.7d, assumed to work with most
  relatively recent versions; this is likely to be available with most
  distributions, http://www.openssl.org/)

This library is only needed when EAP-TLS, EAP-PEAP, or EAP-TTLS
support is enabled. WPA-PSK mode does not require this or EAPOL/EAP
implementation. A configuration file, .config, for compilation is
needed to enable IEEE 802.1X/EAPOL and EAP methods. Note that EAP-MD5,
EAP-GTC, EAP-OTP, and EAP-MSCHAPV2 cannot be used alone with WPA, so
they should only be enabled if testing the EAPOL/EAP state
machines. However, there can be used as inner authentication
algorithms with EAP-PEAP and EAP-TTLS.

See Building and installing section below for more detailed
information about the wpa_supplicant build time configuration.



WPA
---

The original security mechanism of IEEE 802.11 standard was not
designed to be strong and has proven to be insufficient for most
networks that require some kind of security. Task group I (Security)
of IEEE 802.11 working group (http://www.ieee802.org/11/) has worked
to address the flaws of the base standard and has in practice
completed its work in May 2004. The IEEE 802.11i amendment to the IEEE
802.11 standard was approved in June 2004 and published in July 2004.

Wi-Fi Alliance (http://www.wi-fi.org/) used a draft version of the
IEEE 802.11i work (draft 3.0) to define a subset of the security
enhancements that can be implemented with existing wlan hardware. This
is called Wi-Fi Protected Access<TM> (WPA). This has now become a
mandatory component of interoperability testing and certification done
by Wi-Fi Alliance. Wi-Fi provides information about WPA at its web
site (http://www.wi-fi.org/OpenSection/protected_access.asp).

IEEE 802.11 standard defined wired equivalent privacy (WEP) algorithm
for protecting wireless networks. WEP uses RC4 with 40-bit keys,
24-bit initialization vector (IV), and CRC32 to protect against packet
forgery. All these choices have proven to be insufficient: key space is
too small against current attacks, RC4 key scheduling is insufficient
(beginning of the pseudorandom stream should be skipped), IV space is
too small and IV reuse makes attacks easier, there is no replay
protection, and non-keyed authentication does not protect against bit
flipping packet data.

WPA is an intermediate solution for the security issues. It uses
Temporal Key Integrity Protocol (TKIP) to replace WEP. TKIP is a
compromise on strong security and possibility to use existing
hardware. It still uses RC4 for the encryption like WEP, but with
per-packet RC4 keys. In addition, it implements replay protection,
keyed packet authentication mechanism (Michael MIC).

Keys can be managed using two different mechanisms. WPA can either use
an external authentication server (e.g., RADIUS) and EAP just like
IEEE 802.1X is using or pre-shared keys without need for additional
servers. Wi-Fi calls these "WPA-Enterprise" and "WPA-Personal",
respectively. Both mechanisms will generate a master session key for
the Authenticator (AP) and Supplicant (client station).

WPA implements a new key handshake (4-Way Handshake and Group Key
Handshake) for generating and exchanging data encryption keys between
the Authenticator and Supplicant. This handshake is also used to
verify that both Authenticator and Supplicant know the master session
key. These handshakes are identical regardless of the selected key
management mechanism (only the method for generating master session
key changes).



IEEE 802.11i / WPA2
-------------------

The design for parts of IEEE 802.11i that were not included in WPA has
finished (May 2004) and this amendment to IEEE 802.11 was approved in
June 2004. Wi-Fi Alliance is using the final IEEE 802.11i as a new
version of WPA called WPA2. This includes, e.g., support for more
robust encryption algorithm (CCMP: AES in Counter mode with CBC-MAC)
to replace TKIP and optimizations for handoff (reduced number of
messages in initial key handshake, pre-authentication, and PMKSA caching).



wpa_supplicant
--------------

wpa_supplicant is an implementation of the WPA Supplicant component,
i.e., the part that runs in the client stations. It implements WPA key
negotiation with a WPA Authenticator and EAP authentication with
Authentication Server. In addition, it controls the roaming and IEEE
802.11 authentication/association of the wlan driver.

wpa_supplicant is designed to be a "daemon" program that runs in the
background and acts as the backend component controlling the wireless
connection. wpa_supplicant supports separate frontend programs and an
example text-based frontend, wpa_cli, is included with wpa_supplicant.

Following steps are used when associating with an AP using WPA:

- wpa_supplicant requests the kernel driver to scan neighboring BSSes
- wpa_supplicant selects a BSS based on its configuration
- wpa_supplicant requests the kernel driver to associate with the chosen
  BSS
- If WPA-EAP: integrated IEEE 802.1X Supplicant completes EAP
  authentication with the authentication server (proxied by the
  Authenticator in the AP)
- If WPA-EAP: master key is received from the IEEE 802.1X Supplicant