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Linux 2.6 - man page for wpa_supplicant (linux section 8)


       wpa_supplicant - Wi-Fi Protected Access client and IEEE 802.1X supplicant

       wpa_supplicant [ -BddfhKLqqtuvW ] [ -iifname ] [ -cconfig file ] [ -Ddriver ] [ -PPID_file
       ] [ -foutput file ]

       Wireless networks do not require physical access to the network equipment in the same  way
       as wired networks. This makes it easier for unauthorized users to passively monitor a net-
       work and capture all transmitted frames.  In addition, unauthorized use of the network  is
       much  easier.  In many cases, this can happen even without user's explicit knowledge since
       the wireless LAN adapter may have been configured to automatically join any available net-

       Link-layer  encryption  can  be used to provide a layer of security for wireless networks.
       The original wireless LAN standard, IEEE 802.11, included a simple  encryption  mechanism,
       WEP. However, that proved to be flawed in many areas and network protected with WEP cannot
       be consider secure. IEEE 802.1X authentication and frequently changed dynamic WEP keys can
       be  used  to improve the network security, but even that has inherited security issues due
       to the use of WEP for encryption. Wi-Fi Protected Access and IEEE 802.11i amendment to the
       wireless  LAN  standard	introduce a much improvement mechanism for securing wireless net-
       works. IEEE 802.11i enabled networks that are using CCMP (encryption  mechanism	based  on
       strong  cryptographic  algorithm  AES)  can finally be called secure used for applications
       which require efficient protection against unauthorized access.

       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 wireless LAN 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 sep-
       arate  frontend	programs  and  an  example text-based frontend, wpa_cli, is included with

       Before wpa_supplicant can do its work, the network  interface  must  be	available.   That
       means  that the physical device must be present and enabled, and the driver for the device
       must be loaded. The daemon will exit immediately if the device is not already available.

       After wpa_supplicant has configured the network device, higher level configuration such as
       DHCP  may  proceed.   There  are  a  variety  of  ways  to integrate wpa_supplicant into a
       machine's networking scripts, a few of which are described in sections below.

       The following steps are used when associating with an AP using WPA:

       o wpa_supplicant requests the kernel driver to scan neighboring BSSes

       o wpa_supplicant selects a BSS based on its configuration

       o wpa_supplicant requests the kernel driver to associate with the chosen BSS

       o If WPA-EAP: integrated IEEE 802.1X Supplicant	completes  EAP	authentication	with  the
	 authentication server (proxied by the Authenticator in the AP)

       o If WPA-EAP: master key is received from the IEEE 802.1X Supplicant

       o If WPA-PSK: wpa_supplicant uses PSK as the master session key

       o wpa_supplicant  completes WPA 4-Way Handshake and Group Key Handshake with the Authenti-
	 cator (AP)

       o wpa_supplicant configures encryption keys for unicast and broadcast

       o normal data packets can be transmitted and received

       Supported WPA/IEEE 802.11i features:

       o WPA-PSK ("WPA-Personal")

       o WPA with EAP (e.g., with  RADIUS  authentication  server)  ("WPA-Enterprise")	Following
	 authentication methods are supported with an integrate IEEE 802.1X Supplicant:


	 o EAP-PEAP/MSCHAPv2 (both PEAPv0 and PEAPv1)

	 o EAP-PEAP/TLS (both PEAPv0 and PEAPv1)

	 o EAP-PEAP/GTC (both PEAPv0 and PEAPv1)

	 o EAP-PEAP/OTP (both PEAPv0 and PEAPv1)

	 o EAP-PEAP/MD5-Challenge (both PEAPv0 and PEAPv1)

	 o EAP-TTLS/EAP-MD5-Challenge













	 o LEAP (note: requires special support from the driver for IEEE 802.11 authentication)

	 o (following methods are supported, but since they do not generate keying material, they
	   cannot be used with WPA or IEEE 802.1X WEP keying)

	 o EAP-MD5-Challenge




       o key management for CCMP, TKIP, WEP104, WEP40

       o RSN/WPA2 (IEEE 802.11i)

	 o pre-authentication

	 o PMKSA caching

       A summary of available driver backends is below. Support for each of the  driver  backends
       is chosen at wpa_supplicant compile time. For a list of supported driver backends that may
       be used with the -D option on your system, refer to  the  help  output  of  wpa_supplicant
       (wpa_supplicant -h).

       hostap (default) Host AP driver (Intersil Prism2/2.5/3).  (this can also be used with Lin-
	      uxant DriverLoader).

       hermes Agere Systems Inc. driver (Hermes-I/Hermes-II).

	      MADWIFI 802.11 support (Atheros, etc.).

       atmel  ATMEL AT76C5XXx (USB, PCMCIA).

       wext   Linux wireless extensions (generic).

	      Linux ndiswrapper.

	      Broadcom wl.o driver.

       ipw    Intel ipw2100/2200 driver.

       wired  wpa_supplicant wired Ethernet driver

	      wpa_supplicant Broadcom switch driver

       bsd    BSD 802.11 support (Atheros, etc.).

       ndis   Windows NDIS driver.

       Most command line options have global scope. Some are given per interface,  and	are  only
       valid if at least one -i option is specified, otherwise they're ignored. Option groups for
       different interfaces must be separated by -N option.

       -b br_ifname
	      Optional bridge interface name. (Per interface)

       -B     Run daemon in the background.

       -c filename
	      Path to configuration file. (Per interface)

       -C ctrl_interface
	      Path to ctrl_interface socket (Per interface. Only used if -c is not).

       -i ifname
	      Interface to listen on. Multiple instances of this option can be present,  one  per
	      interface, separated by -N option (see below).

       -d     Increase debugging verbosity (-dd even more).

       -D driver
	      Driver  to  use  (can  be multiple drivers: nl80211,wext).  (Per interface, see the
	      available options below.)

       -f output file
	      Log output to specified file instead of stdout.

       -g global ctrl_interface
	      Path to global ctrl_interface socket. If specified, interface  definitions  may  be

       -K     Include keys (passwords, etc.) in debug output.

       -t     Include timestamp in debug messages.

       -h     Help.  Show a usage message.

       -L     Show license (GPL and BSD).

       -p     Driver parameters. (Per interface)

       -P PID_file
	      Path to PID file.

       -q     Decrease debugging verbosity (-qq even less).

       -u     Enabled DBus control interface. If enabled, interface definitions may be omitted.

       -v     Show version.

       -W     Wait for a control interface monitor before starting.

       -N     Start describing new interface.

       In most common cases, wpa_supplicant is started with:

	      wpa_supplicant -B -c/etc/wpa_supplicant.conf -iwlan0

       This makes the process fork into background.

       The  easiest  way  to  debug  problems,	and to get debug log for bug reports, is to start
       wpa_supplicant on foreground with debugging enabled:

	      wpa_supplicant -c/etc/wpa_supplicant.conf -iwlan0 -d

       If the specific driver wrapper is not known beforehand, it is possible to specify multiple
       comma  separated  driver  wrappers  on the command line. wpa_supplicant will use the first
       driver wrapper that is able to initialize the interface.

	      wpa_supplicant -Dnl80211,wext -c/etc/wpa_supplicant.conf -iwlan0

       wpa_supplicant can control multiple interfaces (radios) either by running one process  for
       each  interface	separately  or by running just one process and list of options at command
       line. Each interface is separated with -N argument. As an example, following command would
       start wpa_supplicant for two interfaces:

	      wpa_supplicant \
		   -c wpa1.conf -i wlan0 -D hostap -N \
		   -c wpa2.conf -i ath0 -D madwifi

       Current hardware/software requirements:

       o Linux kernel 2.4.x or 2.6.x with Linux Wireless Extensions v15 or newer

       o FreeBSD 6-CURRENT

       o Microsoft Windows with WinPcap (at least WinXP, may work with other versions)

       Host AP driver for Prism2/2.5/3 (development snapshot/v0.2.x)
	      (http://hostap.epitest.fi/)  Driver needs 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

       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/sup-
	      port/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

       Intel ipw2200 driver

       Linux wireless extensions
	      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
	      Use ap_scan=0.

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

       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 devel-
       oper.txt 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  inter-
       face code in wpa_supplicant.

       The wpa_supplicant system consists of the following components:

	      the  configuration file describing all networks that the user wants the computer to
	      connect to.

	      the program that directly interacts with the network interface.

	      the client program that provides a high-level interface to the functionality of the

	      a  utility  needed  to  construct  wpa_supplicant.conf files that include encrypted

       First, make a configuration file, e.g.  /etc/wpa_supplicant.conf, that describes the  net-
       works you are interested in.  See wpa_supplicant.conf(5) for details.

       Once  the  configuration is ready, you can test whether the configuration works by running
       wpa_supplicant with following command to start it on foreground with debugging enabled:

	      wpa_supplicant -iwlan0 -c/etc/wpa_supplicant.conf -d

       Assuming everything goes fine, you can start using following command to start  wpa_suppli-
       cant on background without debugging:

	      wpa_supplicant -iwlan0 -c/etc/wpa_supplicant.conf -B

       Please note that if you included more than one driver interface in the build time configu-
       ration (.config), you may need to specify which interface to use  by  including	-D<driver
       name> option on the command line.

       For  example,  following small changes to pcmcia-cs scripts can be used to enable WPA sup-

       Add MODE="Managed" and WPA="y" to the network scheme in /etc/pcmcia/wireless.opts.

       Add the following block to the end of start action handler in /etc/pcmcia/wireless:

	      if [ "$WPA" = "y" -a -x /usr/local/bin/wpa_supplicant ]; then
		  /usr/local/bin/wpa_supplicant -B -c/etc/wpa_supplicant.conf -i$DEVICE

       Add the following block to the end of stop action handler (may need to be  separated  from
       other actions) in /etc/pcmcia/wireless:

	      if [ "$WPA" = "y" -a -x /usr/local/bin/wpa_supplicant ]; then
		  killall wpa_supplicant

       This will make cardmgr start wpa_supplicant when the card is plugged in.

       wpa_background(8) wpa_supplicant.conf(5) wpa_cli(8) wpa_passphrase(8)

       wpa_supplicant  is copyright (c) 2003-2007, Jouni Malinen <j@w1.fi> 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.

					07 September 2010			WPA_SUPPLICANT(8)

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