WPA_SUPPLICANT(8) WPA_SUPPLICANT(8)
NAME
wpa_supplicant - Wi-Fi Protected Access client and IEEE 802.1X suppli-
cant
SYNOPSIS
wpa_supplicant [ -BddfhKLqqsTtuvW ] [ -iifname ] [ -cconfig file ] [
-Ddriver ] [ -PPID_file ] [ -foutput file ]
OVERVIEW
Wireless networks do not require physical access to the network equip-
ment in the same way as wired networks. This makes it easier for unau-
thorized users to passively monitor a network and capture all transmit-
ted frames. In addition, unauthorized use of the network is much eas-
ier. In many cases, this can happen even without user's explicit knowl-
edge since the wireless LAN adapter may have been configured to automat-
ically 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, in-
cluded 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 in-
herited security issues due to the use of WEP for encryption. Wi-Fi Pro-
tected Access and IEEE 802.11i amendment to the wireless LAN standard
introduce a much improved mechanism for securing wireless networks. 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 Authen-
tication 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 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 en-
abled, 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:
• 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 authenti-
cation 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-Enter-
prise") Following authentication methods are supported with an inte-
grate 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
roboswitch
wpa_supplicant Broadcom switch driver
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 inter-
face, and are only valid if at least one -i option is specified, other-
wise 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 in-
terface, 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 de-
finitions 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 CONFIG_DEBUG_SYSLOG option.)
-T Log output to Linux tracing in addition to any other destina-
tions. (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 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 ini-
tialize the interface.
wpa_supplicant -Dnl80211,wext -c/etc/wpa_supplicant.conf -iwlan0
wpa_supplicant can control multiple interfaces (radios) either by run-
ning 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_sup-
plicant 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 op-
tion 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://win-
pcap.polito.it/). See README-Windows.txt for more information.
wpa_supplicant was designed to be portable for different drivers and op-
erating 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_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.
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 in-
clude 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_suppli-
cant.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_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 inter-
face to use by including -D<driver name> option on the command line.
INTERFACE TO PCMCIA-CS/CARDMRG
For example, 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/pcm-
cia/wireless.opts.
Add the following block to the end of start action handler in /etc/pcm-
cia/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/pcmcia/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)
LEGAL
wpa_supplicant is copyright (c) 2003-2022, Jouni Malinen <j@w1.fi> and
contributors. All Rights Reserved.
This program is licensed under the BSD license (the one with advertise-
ment clause removed).
07 August 2019 WPA_SUPPLICANT(8)
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