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Manual: wpa_supplicant

WPA_SUPPLICANT(8) WPA_SUPPLICANT(8)

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

SYNOPSIS
wpa_supplicant [ -BddfhKLqqsTtuvW ] [ -iifname ] [ -cconfig file ] [ -Ddriver ] [ -PPID_file ] [ -foutput file ] [
-Iadditional config file ]

OVERVIEW
Wireless networks do not require physical access to the network equipment in the same way that wired networks do.
This makes it easier for unauthorized users to passively monitor a network 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 network.

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 networks protected with WEP cannot be considered secure. IEEE 802.1X authentication and frequently changed dy‐
namic 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 the IEEE 802.11i amendment to the wireless LAN standard intro‐
duce a much improved mechanism for securing wireless networks. IEEE 802.11i enabled networks that are using CCMP (an
encryption mechanism based on the strong cryptographic algorithm AES) can finally be called secure and used for ap‐
plications 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 ad‐
dition, 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 separate frontend programs and an example text-based
frontend, wpa_cli, is included with wpa_supplicant.

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 of the device, 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:

• wpa_supplicant requests the kernel driver to scan neighboring BSSes (Basic Service Set)

• 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

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

• wpa_supplicant completes WPA 4-Way Handshake and Group Key Handshake with the Authenticator (AP)

• wpa_supplicant configures encryption keys for unicast and broadcast

• normal data packets can be transmitted and received

SUPPORTED 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 sup‐
ported 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

AVAILABLE DRIVERS
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).

nl80211
Uses the modern Linux nl80211/cfg80211 netlink-based interface (most new drivers).

wext Uses the legacy Linux wireless extensions ioctl-based interface (older hardware/drivers).

wired wpa_supplicant wired Ethernet driver

macsec_linux
MACsec Ethernet driver for Linux

roboswitch
wpa_supplicant Broadcom switch driver

none no driver (RADIUS server/WPS ER only)

bsd BSD 802.11 support (Atheros, etc.).

ndis Windows NDIS driver.

COMMAND LINE OPTIONS
Most command line options have global scope. Some are given per interface, and are only valid if at least one -i op‐
tion 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).

-I filename
Path to additional configuration file.

-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.)

-e entropy file
File for wpa_supplicant to use to maintain its internal entropy store in over restarts.

-f output file
Log output to specified file instead of stdout. (This is only available if wpa_supplicant was built with the
CONFIG_DEBUG_FILE option.)

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

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

-h Help. Show a usage message.

-L Show license (BSD).

-o override driver
Override the driver parameter for new interfaces.

-O override ctrl_interface
Override the ctrl_interface parameter for new interfaces.

-p Driver parameters. (Per interface)

-P PID_file
Path to PID file.

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

-s Log output to syslog instead of stdout. (This is only available if wpa_supplicant was built with the CON‐
FIG_DEBUG_SYSLOG option.)

-T Log output to Linux tracing in addition to any other destinations. (This is only available if wpa_supplicant
was built with the CONFIG_DEBUG_LINUX_TRACING option.)

-t Include timestamp in debug messages.

-u Enable DBus control interface. If enabled, interface definitions may be omitted. (This is only available if
wpa_supplicant was built with the CONFIG_CTRL_IFACE_DBUS_NEW option.)

-v Show version.

-W Wait for a control interface monitor before starting.

-N Start describing new interface.

EXAMPLES
In most common cases, wpa_supplicant is started with:

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

This makes the process fork into the background.

The easiest way to debug problems, and to get a debug log for bug reports, is to start wpa_supplicant in the fore‐
ground 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 inter‐
face.

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 nl80211 -N \
-c wpa2.conf -i ath0 -D wext

OS REQUIREMENTS
Current hardware/software requirements:

• Linux kernel 2.6.30 or higher with nl80211/cfg80211 support

• Linux kernel 2.4.x or higher with Linux Wireless Extensions v15 or newer

• FreeBSD 6-CURRENT

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

SUPPORTED DRIVERS
Linux nl80211/cfg80211
This is the preferred driver for Linux.

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 infor‐
mation.

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.txt for more information about the design of wpa_sup‐
plicant 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.

ARCHITECTURE
The wpa_supplicant system consists of the following components:

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

wpa_supplicant
the program that directly interacts with the network interface.

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

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

QUICK START
First, make a configuration file, e.g. /etc/wpa_supplicant.conf, that describes the networks 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 follow‐
ing 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_supplicant 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 configuration (.config), you may
need to specify which interface to use by including -D option on the command line.

INTERFACE TO PCMCIA-CS/CARDMRG
For example, the following small changes to pcmcia-cs scripts can be used to enable WPA support:

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
fi

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

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

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

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

This program is licensed under the BSD license (the one with advertisement clause removed).

1 February 2023 WPA_SUPPLICANT(8)

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Manual: wpa_supplicant

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