doc/docbook/wpa_supplicant.sgml

<!doctype refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN">

<refentry>
  <refentryinfo>
    <date>1 February 2023</date>
  </refentryinfo>

  <refmeta>
    <refentrytitle>wpa_supplicant</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>
  <refnamediv>
    <refname>wpa_supplicant</refname>
    <refpurpose>Wi-Fi Protected Access client and IEEE 802.1X supplicant</refpurpose>
  </refnamediv>
  <refsynopsisdiv>
    <cmdsynopsis>
      <command>wpa_supplicant</command>
      <arg>-BddfhKLqqsTtuvW</arg>
      <arg>-i<replaceable>ifname</replaceable></arg>
      <arg>-c<replaceable>config file</replaceable></arg>
      <arg>-D<replaceable>driver</replaceable></arg>
      <arg>-P<replaceable>PID_file</replaceable></arg>
      <arg>-f<replaceable>output file</replaceable></arg>
      <arg>-I<replaceable>additional config file</replaceable></arg>
    </cmdsynopsis>
  </refsynopsisdiv>
  <refsect1>
    <title>Overview</title>

    <para>
    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.
    </para>

    <para>
    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 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 the 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 (an encryption mechanism based on the strong
    cryptographic algorithm AES) can finally be called secure and used for
    applications which require efficient protection against unauthorized
    access.
    </para>

    <para><command>wpa_supplicant</command> 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.</para>

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

    <para>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.</para>

    <para>After <command>wpa_supplicant</command> 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.</para>

    <para>The following steps are used when associating with an AP
    using WPA:</para>

    <itemizedlist>
      <listitem>
	<para><command>wpa_supplicant</command> requests the kernel
	driver to scan neighboring BSSes (Basic Service Set)</para>
      </listitem>

      <listitem>
	<para><command>wpa_supplicant</command> selects a BSS based on
	its configuration</para>
      </listitem>

      <listitem>
	<para><command>wpa_supplicant</command> requests the kernel
        driver to associate with the chosen BSS</para>
      </listitem>

      <listitem>
	<para>If WPA-EAP: integrated IEEE 802.1X Supplicant
        completes EAP authentication with the
        authentication server (proxied by the Authenticator in the
        AP)</para>
      </listitem>

      <listitem>
	<para>If WPA-EAP: master key is received from the IEEE 802.1X
	Supplicant</para>
      </listitem>

      <listitem>
	<para>If WPA-PSK: <command>wpa_supplicant</command> uses PSK
	as the master session key</para>
      </listitem>

      <listitem>
	<para><command>wpa_supplicant</command> completes WPA 4-Way
        Handshake and Group Key Handshake with the Authenticator
        (AP)</para>
      </listitem>

      <listitem>
	<para><command>wpa_supplicant</command> configures encryption
	keys for unicast and broadcast</para>
      </listitem>

      <listitem>
	<para>normal data packets can be transmitted and received</para>
      </listitem>
    </itemizedlist>
  </refsect1>

  <refsect1>
    <title>Supported Features</title>
    <para>Supported WPA/IEEE 802.11i features:</para>
    <itemizedlist>
      <listitem>
	<para>WPA-PSK ("WPA-Personal")</para>
      </listitem>

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

	<itemizedlist>
	  <listitem>
	    <para>EAP-TLS</para>
	  </listitem>
	</itemizedlist>

	<itemizedlist>
	  <listitem>
	    <para>EAP-PEAP/MSCHAPv2 (both PEAPv0 and PEAPv1)</para>
	  </listitem>


	  <listitem>
	    <para>EAP-PEAP/TLS (both PEAPv0 and PEAPv1)</para>
	  </listitem>

	  <listitem>
	    <para>EAP-PEAP/GTC (both PEAPv0 and PEAPv1)</para>
	  </listitem>

	  <listitem>
	    <para>EAP-PEAP/OTP (both PEAPv0 and PEAPv1)</para>
	  </listitem>

	  <listitem>
	    <para>EAP-PEAP/MD5-Challenge (both PEAPv0 and PEAPv1)</para>
	  </listitem>

	  <listitem>
	    <para>EAP-TTLS/EAP-MD5-Challenge</para>
	  </listitem>

	  <listitem>
	    <para>EAP-TTLS/EAP-GTC</para>
	  </listitem>

          <listitem><para>EAP-TTLS/EAP-OTP</para></listitem>

          <listitem><para>EAP-TTLS/EAP-MSCHAPv2</para></listitem>

          <listitem><para>EAP-TTLS/EAP-TLS</para></listitem>

          <listitem><para>EAP-TTLS/MSCHAPv2</para></listitem>

          <listitem><para>EAP-TTLS/MSCHAP</para></listitem>

          <listitem><para>EAP-TTLS/PAP</para></listitem>

          <listitem><para>EAP-TTLS/CHAP</para></listitem>

          <listitem><para>EAP-SIM</para></listitem>

          <listitem><para>EAP-AKA</para></listitem>

          <listitem><para>EAP-PSK</para></listitem>

          <listitem><para>EAP-PAX</para></listitem>

          <listitem><para>LEAP (note: requires special support from
          the driver for IEEE 802.11 authentication)</para></listitem>

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

          <listitem><para>EAP-MD5-Challenge </para></listitem>

          <listitem><para>EAP-MSCHAPv2</para></listitem>

          <listitem><para>EAP-GTC</para></listitem>

          <listitem><para>EAP-OTP</para></listitem>
	</itemizedlist>
      </listitem>

      <listitem>
	<para>key management for CCMP, TKIP, WEP104, WEP40</para>
      </listitem>

      <listitem>
	<para>RSN/WPA2 (IEEE 802.11i)</para>
	<itemizedlist>
	  <listitem>
	    <para>pre-authentication</para>
	  </listitem>

	  <listitem>
	    <para>PMKSA caching</para>
	  </listitem>
	</itemizedlist>
      </listitem>
    </itemizedlist>
  </refsect1>

  <refsect1>
    <title>Available Drivers</title>
    <para>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
    (<emphasis>wpa_supplicant -h</emphasis>).</para>

    <variablelist>
      <varlistentry>
	<term>nl80211</term>
	<listitem>
	  <para>Uses the modern Linux nl80211/cfg80211 netlink-based
	  interface (most new drivers).</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>wext</term>
	<listitem>
	  <para>Uses the legacy Linux wireless extensions ioctl-based
	  interface (older hardware/drivers).</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>wired</term>
	<listitem>
	  <para>wpa_supplicant wired Ethernet driver</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>macsec_linux</term>
	<listitem>
	  <para>MACsec Ethernet driver for Linux</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>roboswitch</term>
	<listitem>
	  <para>wpa_supplicant Broadcom switch driver</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>none</term>
	<listitem>
	  <para>no driver (RADIUS server/WPS ER only)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>bsd</term>
	<listitem>
	  <para>BSD 802.11 support (Atheros, etc.).</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>ndis</term>
	<listitem>
	  <para>Windows NDIS driver.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Command Line Options</title>
    <para>Most command line options have global scope. Some are given per
    interface, and are only valid if at least one <option>-i</option> option
    is specified, otherwise they're ignored. Option groups for different
    interfaces must be separated by <option>-N</option> option.</para>
    <variablelist>
      <varlistentry>
	<term>-b br_ifname</term>
	<listitem>
	  <para>Optional bridge interface name. (Per interface)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-B</term>
	<listitem>
	  <para>Run daemon in the background.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-c filename</term>
	<listitem>
	  <para>Path to configuration file. (Per interface)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-C ctrl_interface</term>
	<listitem>
	  <para>Path to ctrl_interface socket (Per interface. Only used if
		  <option>-c</option> is not).</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-i ifname</term>
	<listitem>
	  <para>Interface to listen on. Multiple instances of this option can
	  be present, one per interface, separated by <option>-N</option>
	  option (see below).</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-I filename</term>
	<listitem>
          <para>Path to additional configuration file.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-d</term>
	<listitem>
	  <para>Increase debugging verbosity (<option>-dd</option> even
		  more).</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-D driver</term>
	<listitem>
	  <para>Driver to use (can be multiple drivers: nl80211,wext).
		  (Per interface, see the available options below.)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-e entropy file</term>
	<listitem>
	  <para>File for <command>wpa_supplicant</command> to use to
	  maintain its internal entropy store in over restarts.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-f output file</term>
	<listitem>
	  <para>Log output to specified file instead of stdout. (This
	  is only available if <command>wpa_supplicant</command> was
	  built with the <literal>CONFIG_DEBUG_FILE</literal>
	  option.)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-g global ctrl_interface</term>
	<listitem>
	  <para>Path to global ctrl_interface socket. If specified, interface
	  definitions may be omitted.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-K</term>
	<listitem>
	  <para>Include keys (passwords, etc.) in debug output.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-h</term>
	<listitem>
	  <para>Help.  Show a usage message.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-L</term>
	<listitem>
	  <para>Show license (BSD).</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-o override driver</term>
	<listitem>
	  <para>Override the driver parameter for new
	  interfaces.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-O override ctrl_interface</term>
	<listitem>
	  <para>Override the ctrl_interface parameter for new
	  interfaces.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-p</term>
	<listitem>
	  <para>Driver parameters. (Per interface)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-P PID_file</term>
	<listitem>
	  <para>Path to PID file.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-q</term>
	<listitem>
	  <para>Decrease debugging verbosity (<option>-qq</option> even
		  less).</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-s</term>
	<listitem>
	  <para>Log output to syslog instead of stdout. (This is only
	  available if <command>wpa_supplicant</command> was built
	  with the <literal>CONFIG_DEBUG_SYSLOG</literal>
	  option.)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-T</term>
	<listitem>
	  <para>Log output to Linux tracing in addition to any other
	  destinations. (This is only available
	  if <command>wpa_supplicant</command> was built with
	  the <literal>CONFIG_DEBUG_LINUX_TRACING</literal>
	  option.)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-t</term>
	<listitem>
	  <para>Include timestamp in debug messages.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-u</term>
	<listitem>
	  <para>Enable DBus control interface. If enabled, interface
	  definitions may be omitted. (This is only available
	  if <command>wpa_supplicant</command> was built with
	  the <literal>CONFIG_CTRL_IFACE_DBUS_NEW</literal> option.)</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-v</term>
	<listitem>
	  <para>Show version.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-W</term>
	<listitem>
	  <para>Wait for a control interface monitor before starting.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>-N</term>
	<listitem>
	  <para>Start describing new interface.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Examples</title>

    <para>In most common cases, <command>wpa_supplicant</command> is
    started with:</para>

<blockquote><programlisting>
wpa_supplicant -B -c/etc/wpa_supplicant.conf -iwlan0
</programlisting></blockquote>

    <para>This makes the process fork into the background.</para>

    <para>The easiest way to debug problems, and to get a debug log for
    bug reports, is to start <command>wpa_supplicant</command> in the
    foreground with debugging enabled:</para>

<blockquote><programlisting>
wpa_supplicant -c/etc/wpa_supplicant.conf -iwlan0 -d
</programlisting></blockquote>

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

<blockquote><programlisting>
wpa_supplicant -Dnl80211,wext -c/etc/wpa_supplicant.conf -iwlan0
</programlisting></blockquote>

    <para><command>wpa_supplicant</command> 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:</para>

<blockquote><programlisting>
wpa_supplicant \
	-c wpa1.conf -i wlan0 -D nl80211 -N \
	-c wpa2.conf -i ath0 -D wext
</programlisting></blockquote>
  </refsect1>

  <refsect1>
    <title>OS Requirements</title>
    <para>Current hardware/software requirements:</para>

    <itemizedlist>
      <listitem>
	<para>Linux kernel 2.6.30 or higher with
	nl80211/cfg80211 support</para>
      </listitem>

      <listitem>
	<para>Linux kernel 2.4.x or higher with Linux Wireless
	Extensions v15 or newer</para>
      </listitem>

      <listitem>
	<para>FreeBSD 6-CURRENT</para>
      </listitem>

      <listitem>
	<para>Microsoft Windows with WinPcap (at least WinXP, may work
	with other versions)</para>
      </listitem>
    </itemizedlist>
  </refsect1>

  <refsect1>
    <title>Supported Drivers</title>
    <variablelist>
      <varlistentry>
	<term>Linux nl80211/cfg80211</term>
	<listitem>
	  <para>This is the preferred driver for Linux.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>Linux wireless extensions</term>
	<listitem>
	  <para>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.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>Wired Ethernet drivers</term>
	<listitem>
	  <para>Use ap_scan=0.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>BSD net80211 layer (e.g., Atheros driver)</term>
	<listitem>
	  <para>At the moment, this is for FreeBSD 6-CURRENT branch.</para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term>Windows NDIS</term>
	<listitem>
	  <para>The current Windows port requires WinPcap
	(http://winpcap.polito.it/).  See README-Windows.txt for more
	information.</para>
	</listitem>
      </varlistentry>
    </variablelist>


    <para>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_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.</para>
  </refsect1>

  <refsect1>
    <title>Architecture</title> <para>The
    <command>wpa_supplicant</command> system consists of the following
    components:</para>

    <variablelist>
      <varlistentry>
	<term><filename>wpa_supplicant.conf</filename> </term>
	<listitem>
        <para>the configuration file describing all networks that the
        user wants the computer to connect to.  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><command>wpa_supplicant</command></term>
        <listitem><para>the program that directly interacts with the
        network interface.  </para></listitem>
      </varlistentry>
      <varlistentry>
	<term><command>wpa_cli</command></term> <listitem><para> the
	client program that provides a high-level interface to the
	functionality of the daemon.  </para></listitem>
      </varlistentry>
      <varlistentry>
	<term><command>wpa_passphrase</command></term>
        <listitem><para>a utility needed to construct
        <filename>wpa_supplicant.conf</filename> files that include
        encrypted passwords.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Quick Start</title>

    <para>First, make a configuration file, e.g.
    <filename>/etc/wpa_supplicant.conf</filename>, that describes the networks
    you are interested in.  See <citerefentry>
	<refentrytitle>wpa_supplicant.conf</refentrytitle>
	<manvolnum>5</manvolnum>
      </citerefentry>
    for details.</para>

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

    <blockquote><programlisting>
wpa_supplicant -iwlan0 -c/etc/wpa_supplicant.conf -d
    </programlisting></blockquote>

    <para>Assuming everything goes fine, you can start using following
    command to start <command>wpa_supplicant</command> on background
    without debugging:</para>

    <blockquote><programlisting>
wpa_supplicant -iwlan0 -c/etc/wpa_supplicant.conf -B
    </programlisting></blockquote>

    <para>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&lt;driver
    name&gt; option on the command line.</para>

    <!-- XXX at this point, the page could include a little script
         based on wpa_cli to wait for a connection and then run
         dhclient -->

  </refsect1>

  <refsect1>
    <title>Interface to pcmcia-cs/cardmrg</title>

    <para>For example, the following small changes to pcmcia-cs scripts
    can be used to enable WPA support:</para>

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

    <para>Add the following block to the end of <emphasis>start</emphasis>
    action handler in <filename>/etc/pcmcia/wireless</filename>:</para>

    <blockquote><programlisting>
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
    </programlisting></blockquote>


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

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

    <para>This will make <command>cardmgr</command> start
    <command>wpa_supplicant</command> when the card is plugged
    in.</para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry>
	<refentrytitle>wpa_background</refentrytitle>
	<manvolnum>8</manvolnum>
      </citerefentry>
      <citerefentry>
	<refentrytitle>wpa_supplicant.conf</refentrytitle>
	<manvolnum>5</manvolnum>
      </citerefentry>
      <citerefentry>
	<refentrytitle>wpa_cli</refentrytitle>
	<manvolnum>8</manvolnum>
      </citerefentry>
      <citerefentry>
	<refentrytitle>wpa_passphrase</refentrytitle>
	<manvolnum>8</manvolnum>
      </citerefentry>
    </para>
  </refsect1>
  <refsect1>
    <title>Legal</title>
    <para>wpa_supplicant is copyright (c) 2003-2022,
    Jouni Malinen <email>j (a] w1.fi</email> and
    contributors.
    All Rights Reserved.</para>

    <para>This program is licensed under the BSD license (the one with
    advertisement clause removed).</para>
  </refsect1>
</refentry>