<sect1 id="npcap-users-guide">
  <title>Npcap Users' Guide</title>
  <sect1info>
    <abstract>
      <para>The Users' Guide covers the basics of installing and removing
        Npcap, interactions with WinPcap, frequently asked questions,
        and how to report bugs.</para>
    </abstract>
  </sect1info>

  <para>Because Npcap is a packet capture architecture, not merely a software
    library, some aspects of installation and configuration may fall to the end
    user. This Users' Guide covers the basics of installing, configuring, and
    removing Npcap, as well as how to report bugs.</para>

  <sect2 id="npcap-installation">
    <title>Installation</title>

    <para>
      Npcap is distributed as a signed executable installer, downloadable from
      <ulink url="https://npcap.com/#download">Nmap.com</ulink>. Major
      versions are backwards-compatible, and users of the free non-commercial
      version are encouraged to upgrade regularly for security and stability
      fixes. Software distributors may have separate requirements for supported
      Npcap versions.  Please refer to
      <ulink url="https://npcap.com/#license">the Npcap License</ulink> for
      terms of use and redistribution.</para>

    <para>
      The Npcap installer and uninstaller are easy to use in
      <quote>Graphical Mode</quote> (direct run) and <quote>Silent Mode</quote> (run with
      <option>/S</option> parameter, available only with <ulink url="https://npcap.com/oem/">Npcap OEM</ulink>).
    </para>

    <sect3 id="npcap-installation-exit">
      <title>Installer exit codes</title>
			<para>The Npcap installer provides information about its execution via the process exit code. The exit
				codes defined are as follows:</para>
			<itemizedlist>
				<listitem><para><literal>0</literal>: Normal execution, no error.</para></listitem>
				<listitem><para><literal>1</literal>: Installation aborted by user (cancel button).</para></listitem>
				<listitem><para><literal>2</literal>: Installation aborted by script.</para></listitem>
				<listitem><para><literal>350</literal> (<literal>ERROR_FAIL_NOACTION_REBOOT</literal>): Installation failed; reboot and try again.</para></listitem>
				<listitem><para><literal>1618</literal> (<literal>ERROR_INSTALL_ALREADY_RUNNING</literal)>): Another installation is already in progress. Complete that installation before proceeding with this install.</para></listitem>
				<listitem><para><literal>1633</literal> (<literal>ERROR_INSTALL_PLATFORM_UNSUPPORTED</literal)>): Npcap is not supported on this platform.</para></listitem>
				<listitem><para><literal>3010</literal> (<literal>ERROR_SUCCESS_REBOOT_REQUIRED</literal>): Installation succeeded; reboot required before Npcap is ready to use.</para></listitem>
			</itemizedlist>

      <para>It is important to note that the installer is a backgrounded app (even in silent mode) and so to get
        the correct process exit code, you need to launch and wait for it. Two ways to do this are using 
        <command>start /wait</command> in <literal>cmd.exe</literal> or <command>Start-Process -Wait</command>
				in PowerShell.</para>

        <para>In the case of return code 2, and in general, it is best to verify a working Npcap installation
          instead of relying on the installer exit code. This could include checking for the
					<literal>npcap</literal> driver service or verifying the Npcap DLLs can be loaded and calling
					<function>pcap_version</function>.</para>
    </sect3>

    <sect3 id="npcap-installation-options">
      <title>Installer options</title>
      <para>
        The installer accepts several command-line options that correspond to the
        options presented in the graphical interface (GUI).  The options can be
        set by command-line flags taking the form
        <option>/<replaceable>name</replaceable>=<replaceable>value</replaceable></option>.
      </para>
      <para>The values for these options must be one of:
      </para>
      <itemizedlist>
        <listitem><para><option>yes</option>: select the option</para></listitem>
        <listitem><para><option>no</option>: unselect the option</para></listitem>
        <listitem><para><option>enforced</option>: select the option and make it unchangable in the GUI</para></listitem>
        <listitem><para><option>disabled</option>: unselect the option and make it unchangable in the GUI</para></listitem>
      </itemizedlist>
      <sect4 id="npcap-installer-options-gui">
        <title>Graphical installer options</title>
        <para>The following options are presented as checkboxes in the
          installer, but can be set or locked via command-line flags. Unless
          otherwise noted, the default for these options is <option>no</option>.
        </para>

        <variablelist>
          <varlistentry>
            <term><option>/loopback_support</option></term>
            <listitem><para>
		<emphasis>Legacy loopback support for Nmap 7.80 and older. Not needed for Wireshark.</emphasis>
		Older versions of Npcap required a Microsoft KM-TEST loopback
		adapter to be installed in order to capture and inject loopback
		traffic. This is no longer needed, but some software won't be
		able to do loopback injection unless the adapter is installed.
		Use this option to install the legacy loopback adapter if
		needed.
              </para>
              <para>See <xref linkend="npcap-feature-loopback" /> for more
                information.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/admin_only</option></term>
            <listitem><para>
                <emphasis>Restrict Npcap driver's access to Administrators
                  only</emphasis>. When this option is chosen, the devices
                created by the Npcap driver for capture and injection on each
                network adapter will be created with a restrictive ACL that
                only allows access to the device by the SYSTEM and built-in
                Administrators. Because this level of access requires UAC
                elevation, a helper binary, <literal>NpcapHelper.exe</literal>,
                is used to request elevation for each process that opens a
                capture handle.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/dot11_support</option></term>
            <listitem><para>
                <emphasis>Support raw 802.11 traffic (and monitor mode) for
                  wireless adapters</emphasis>. This option installs a second
                Lightweight Filter Driver that uses the Native WiFi API to
                capture raw 802.11 WiFi frames on devices that are put into
                network monitor mode. Captured frames are given a Radiotap
                header. Not all hardware or network drivers support the Native
                WiFi API.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/winpcap_mode</option></term>
            <listitem><para>
                <emphasis>Install Npcap in WinPcap API-compatible
                  Mode</emphasis>. The default for this option is
		  <option>yes</option> in Npcap 0.9985 and later. Npcap's DLLs
                    have always been installed into a separate
                    <literal>Npcap</literal> subdirectory of the system
                    directory to avoid conflicting with existing WinPcap
                    installations. This option also installs the DLLs to the
                    system directory, replacing WinPcap. Any existing WinPcap
                    installation will be removed.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/prior_driver</option></term>
            <listitem><para>
		<emphasis>Install older (version 1.30) Npcap driver on pre-Windows-10 systems</emphasis>.
		Some, but not all, ancient Windows systems (so old that Microsoft no longer supports them)
		refuse to install the latest Npcap drivers for signature validation reasons.  They don't
		support the
		<ulink url="https://learn.microsoft.com/en-us/windows-hardware/drivers/dashboard/code-signing-attestation"
			>modern attestation signing method</ulink>, but also can't use drivers signed after
		<ulink url="https://learn.microsoft.com/en-us/windows-hardware/drivers/install/deprecation-of-software-publisher-certificates-and-commercial-release-certificates"
			>Microsoft let their cross-signing certificates for the old method expire in July
			2021</ulink>.  If your Npcap install fails on a pre-Win10 OS (especially with error
		code <varname>0xe0000247</varname>), try again with <option>/prior_driver=yes</option>. This
		option isn't the default because many/most old Windows systems still accept the newest Npcap
		drivers. They may be configured with less-strict codesigning requirements.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/latest_driver</option></term>
            <listitem><para>
		<emphasis>Install the latest Npcap driver on pre-Windows-10 systems</emphasis>.
		Depending on system configuration, many older Windows systems have been accepting our driver
                signatures through Npcap 1.79 because our certificate still chained back to the Microsoft
                cross-certificates. Since that certificate expired in June 2024, most of these Windows 7
                through 8.1 systems will not accept Npcap drivers later than 1.79. These last compatible
		drivers are installed by default, but users can override this using the
		<option>/latest_driver=yes</option> option.
            </para></listitem>
          </varlistentry>
        </variablelist>
      </sect4>

      <sect4 id="npcap-installer-options-cli">
        <title>Command-line installation options</title>
        <para>Some advanced or deprecated options are only available on the
          command-line. Options marked <literal>(deprecated)</literal> are
          subject to removal in future versions.</para>

        <variablelist>
          <varlistentry>
            <term><option>/S</option> (Silent install, Npcap OEM only)</term>
            <listitem><para>
                Installs Npcap without showing any graphical windows or
                prompts. Silent install is available only for Npcap OEM.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/disable_restore_point</option></term>
            <listitem><para>
                The default for this option is <option>yes</option>, so the
                installer will not set a system restore point.  Windows may
                independently create a restore point because of the driver
                installation independent from this option. To ensure a
                restore point is made, specify
                <option>/disable_restore_point=no</option>.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/no_kill</option></term>
            <listitem><para>
                Control termination of
                processes using Npcap during upgrades or WinPcap when
                <option>/winpcap_mode=yes</option> is chosen. See
                <xref linkend="npcap-installation-uninstall-options" />
                for more detailed discussion.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/require_version</option></term>
            <listitem><para>
		Uninstall and replace an existing Npcap installation even if it
		is newer than this version of the installer. By default, the
		Npcap installer will not remove and replace a version of Npcap
		that is newer than its own. In GUI mode, this hides the message
		box asking the user how to proceed.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/require_features</option></term>
            <listitem><para>
		Uninstall and replace an existing Npcap installation of any
		version if it does not provide the same features as the other
		command-line options specify. Features are the /winpcap_mode,
		/dot11_support, /loopback_support, and /admin_only options.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/force</option></term>
            <listitem><para>
		Uninstall and replace an existing Npcap installation regardless
		of version or whether the installation would be modified. By
		default, the Npcap installer will not remove and replace a
		Npcap installation of the same version unless the install
		options would be modified. In GUI mode, this hides the message
		box asking the user how to proceed.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/D</option> (destination directory)</term>
            <listitem><para>
                The destination directory for installation can be overridden by
                the <option>/D</option> option, with a few restrictions. First, it will
                only affect where Npcap keeps its installation logs and helper utilities.
                The driver and DLLs will always be installed into the appropriate
                directories below <command>%SYSTEMROOT%\System32\</command>. Second, the
                <option>/D</option> must be the last option in the command, and the path
                must not contain quotes. This option is case-sensitive. For example, to change the installation directory
                to <filename>C:\Path With Spaces\</filename>, the invocation would be:
                <command>npcap-<replaceable>version</replaceable>.exe /D=C:\Path With Spaces</command>
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/npf_startup</option> (deprecated)</term>
            <listitem><para>
                <emphasis>Automatically start the Npcap driver at boot
                  time</emphasis>. This option defaults to
                <option>yes</option>, because Windows expects NDIS filter
                drivers to be available at boot time. If you choose to disable
                this, Windows may not start networking for up to 90 seconds
                after boot.
            </para></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>/vlan_support</option> (deprecated, ignored)</term>
            <listitem><para>
                <emphasis>Support 802.1Q VLAN tag when capturing and sending
                  data (currently unsupported)</emphasis>. This feature was
                disabled in 2016 to prevent a crash and has not been
                re-enabled.
            </para></listitem>
          </varlistentry>
        </variablelist>

      </sect4>
    </sect3>

    <sect3 id="npcap-installation-uninstall-options">
      <title>Uninstaller options</title>
      <para>
        The uninstaller provided with Npcap also accepts some command-line options.
      </para>
      <variablelist>
        <varlistentry>
          <term><option>/S</option> (Silent uninstall)</term>
          <listitem>
            <para>Uninstalls Npcap without showing any graphical windows or
              prompts. Silent uninstall is available in all editions of Npcap,
              not just Npcap OEM. If Npcap OEM installer in silent mode needs
              to uninstall an older Npcap installation, it passes the
              <option>/S</option> option to the existing uninstaller. This option is case-sensitive.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><option>/Q</option> (Quick uninstall)</term>
          <listitem>
            <para>Skips the confirmation page and finish page in the uninstall
            wizard. This option does not have any meaning for silent
            uninstalls.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><option>/no_kill</option>=<replaceable>yes|no</replaceable> (do not kill processes)</term>
          <listitem>
            <para>Controls how the uninstaller handles processes that are still using
              Npcap at the time of uninstall. The default value is
              <literal>no</literal>, which allows the uninstaller to terminate
              processes that would block Npcap from being uninstalled. If
              <option>/no_kill=yes</option> is specified, then Npcap
              uninstaller will fail if there are still applications using Npcap
              driver or DLLs.</para>

            <para>In the default case, <option>/no_kill=no</option>, the
              graphical uninstaller will give the user the choice to manually
              close the offending programs, have the uninstaller terminate
              them, or abort the uninstallation.  In silent mode, Npcap
              uninstaller will immediately terminate any command-line processes
              that are using Npcap (like a Nmap process that is still
              scanning), and wait for at most 15 seconds to gracefully
              terminate any GUI processes that are using Npcap (like Wireshark
              UI that is still capturing).  <quote>Gracefully</quote> means
              that if you are still capturing via Wireshark, Wireshark UI will
              prompt the user about whether to save the current capture before
              closing. The user will have 15 seconds to save his session.
              <emphasis>Note:</emphasis> although Npcap uninstaller won't
              terminate Wireshark UI processes immediately, the live capture
              stops immediately. This is because Wireshark UI uses command-line
              processes named <varname>dumpcap.exe</varname> to capture, and
              that command-line process will be terminated immediately.</para>

            <para>If this option is provided on the
              <emphasis>installer</emphasis> command line, it will be passed to
              the Npcap uninstaller when doing an upgrade or
              replacement.</para>
          </listitem>
        </varlistentry>
      </variablelist>

    </sect3>

    <sect3 id="npcap-installation-options-disabled">
      <title>Disabled and enforced options for GUI Mode</title>

      <para>
        We may disable or enforce certain options in the installer GUI to make them unselectable. This
        usually means that those options can easily cause compatibility issues and are considered
        not suitable for most users, or we think we need to enforce some rules for the Npcap API. Advanced users can still change their states via command-line
        parameters, which is described in following sections.
      </para>

      <para>
        Fortunately, if a distributor wants to start the Npcap installer GUI and disable or enforce
        certain options for reasons like compatibility. It can also use the four value
        mechanism by setting the command-line parameters to <option>disabled</option> or <option>enforced</option>.
        For example, the following command will start an installer GUI with the
        <option>loopback_support</option> option disabled and unselected:
      </para>

      <para>
        <command>npcap-<replaceable>version</replaceable>.exe /loopback_support=disabled</command>
      </para>
    </sect3>

  </sect2>

  <sect2 id="npcap-watchdog">
    <title>The <literal>npcapwatchdog</literal> scheduled task</title>
    <para>
      Due to the complexities of installing Npcap as a device driver and an NDIS filter driver, Windows
      Feature Updates have occasionally uninstalled the Npcap driver, leading to a broken installation. To
      reduce the likelihood and impact of such a removal, the Npcap installer creates a scheduled task
      named <literal>npcapwatchdog</literal> that runs once at each system startup. The script executes
      the <filename>CheckStatus.bat</filename> script from the Npcap installation directory to determine
      whether the Npcap service is running and installed correctly. If it finds a problem, it runs the
      adjacent <filename>FixInstall.bat</filename> script to reinstall the Npcap driver.</para>
  </sect2>

  <sect2 id="npcap-platforms">
    <title>Windows platforms supported</title>
    <para>Npcap supports all Windows versions currently supported by Microsoft. Depending on Windows version, the
      driver may support a different NDIS version, which corresponds to a set of network stack
      features.</para>
    <itemizedlist>
      <listitem>
        <para>On <emphasis>Windows 11</emphasis>, <emphasis>Windows Server 2022</emphasis>,
        <emphasis>Windows 10</emphasis>, <emphasis>Windows Server 2016</emphasis>, and
        <emphasis>Windows Server 2019</emphasis>, Npcap installs a NDIS 6.50
          driver.</para></listitem>
      <listitem>
        <para>On <emphasis>Windows 8.1</emphasis>, <emphasis>Windows 8</emphasis>,
        <emphasis>Windows Server 2012 R2</emphasis>, and
        <emphasis>Windows Server 2012</emphasis>,
          Npcap installs a NDIS 6.30 driver.</para></listitem>
      <listitem>
        <para>On <emphasis>Windows 7</emphasis> and <emphasis>Windows Server 2008 R2</emphasis>, Npcap
          installs a NDIS 6.20 driver.</para></listitem>
    </itemizedlist>
    <para>Microsoft ended Extended support for Windows versions prior to Windows 10 on January 10, 2023. Future
      Npcap releases <emphasis>may</emphasis> omit support for these operating systems, especially after
      Microsoft ends the pricier Extended Security Update support in 2024 for Server 2008 R2 and in 2026
      for Server 2012 R2.</para>
    <para>Npcap can be installed on x86, x86-64, and ARM64. DLLs for the native architecture will be installed, as
      well as x86 DLLs for applications running in 32-bit emulation.</para>
  </sect2>

  <sect2 id="npcap-feature-dot11-wireshark">
    <title>How to use Wireshark to capture raw 802.11 traffic in <quote>Monitor Mode</quote></title>

    <para>
      The latest Wireshark has already integrated the support for Npcap's <quote>Monitor Mode</quote> capture.
      If you want to use Wireshark to capture raw 802.11 traffic in <quote>Monitor Mode</quote>, you need to
      switch on the monitor mode inside the Wireshark UI instead of using <xref linkend="npcap-feature-dot11-wlanhelper" />.
      This is because Wireshark only recognizes the monitor mode set by itself. So when you turn
      on monitor mode outside Wireshark (like in <filename>WlanHelper</filename>), Wireshark will not know the adapter
      has been in monitor mode, and will still try to capture in Ethernet mode, which will get no traffic.
<!-- TODO: Change instructions in other sections to reflect this. Verify that it is correct, first -->
      So after all, the correct steps are:
    </para>

    <itemizedlist>
      <listitem><para>Install latest version Wireshark and latest version Npcap with
          <option>Support raw 802.11 traffic</option> option checked.</para></listitem>

      <listitem><para>Launch Wireshark QT UI (GTK version is similar), go to <quote>Capture options</quote>.
          Then toggle the checkbox in the <quote>Monitor Mode</quote> column of your wireless adapter's row.
          Click the <quote>Start</quote> button. If you see a horizontal line instead of the checkbox,
          then it probably means that your adapter doesn't support monitor mode. You can use the
          <filename>WlanHelper</filename> tool to double-check this fact.</para></listitem>

      <listitem><para>To decrypt <emphasis>encrypted 802.11 data</emphasis>
          packets, you need to specify the decipher key in Wireshark, otherwise
          you will only see 802.11 data packets.</para></listitem>

      <listitem><para>Stop the capture in Wireshark UI when you finishes capturing, the monitor mode
          will be turned off automatically by Npcap.</para></listitem>
    </itemizedlist>
  </sect2>

  <sect2 id="npcap-qa">
    <title>Q &amp; A</title>

    <itemizedlist>
	<listitem><para>Network interruption while installing Npcap: Installing a filter driver may
	    cause brief interruptions to network connectivity based on the specific changes needed
	    to install the driver in the network stack. This known issue is documented as
	    <ulink role="hidepdf" url="">issue #53</ulink> on our tracker.</para>
	<para> A separate issue is a longer interruption in connectivity if the
	    <varname>npcap</varname> service is not started, which used to be an installer option.
	    As Microsoft states <ulink role="hidepdf" url="https://support.microsoft.com/en-us/kb/2019184">here</ulink>,
          <emphasis>an optional NDIS light-weight filter (LWF) driver like Npcap could cause
            90-second delay in network availability</emphasis>. Some solutions you could try
          are: 1) wait for 90 seconds; 2) disable and re-enable the adapter icon in
          <command>ncpa.cpl</command>; 3) reboot. If the network is still unable to connect,
          please <ulink role="hidepdf" url="http://issues.npcap.org/new?title=Npcap+Bug+Report">file a bug report</ulink>.
      </para></listitem>
      <listitem><para>Installation fails with error code <varname>0x8004a029</varname>:
          The cause is that you have <quote>reached the maximum number of network filter
            drivers</quote>, see solution
          <ulink role="hidepdf" url="https://social.technet.microsoft.com/Forums/windows/en-US/4deb27fc-33ce-4fc0-a26f-3fec5b57733d/is-there-a-maximum-number-of-network-filter-drivers-in-windows-7?forum=w7itpronetworking">here</ulink>.
      </para></listitem>
      <listitem><para>Npcap Adapter for Loopback Capture is missing:
          Npcap's loopback capture is based on the Windows Filtering Platform (WFP), so it depends on the <varname>Base Filtering Enging (BFE)</varname>
          service. To fix this issue, you should start this service at <varname>services.msc</varname>
          manually and restart the Npcap service by running <command>net stop npcap</command>
          and <command>net start npcap</command>. See details about this issue
          <ulink role="hidepdf" url="https://github.com/nmap/npcap/issues/426">here</ulink>.
      </para></listitem>

      <listitem><para>Npcap only captures TCP handshake and teardown, but not data packets:
        A deprecated and uncommon network adapter feature called
        <ulink role="hidepdf" url="https://techcommunity.microsoft.com/blog/coreinfrastructureandsecurityblog/why-are-we-deprecating-network-performance-features-kb4014193/259053">TCP Chimney</ulink>
	can cause this issue. Disable TCP Chimney in the network adapter properties on Windows.
      </para></listitem>

      <listitem><para>Captured packets have incorrect checksums or large sizes:
        Generally speaking, offload features of a miniport driver and/or NIC
        mean that the version of the packet that Npcap sees within the Windows
        network stack may be different in some way from the packet that ends up
        on the physical link. Usually, this is evident as a zero or incorrect
        TCP, UDP, or IP checksum for sent packets, but it can also appear as
        extra-large packets (greater than the TCP MSS or the link maximum frame
        size) received when RSC is enabled. For most purposes, this is not a
        problem, since the payload data is the same, but it may be relevant for
      users who want or need a more forensically-sound packet capture.
      These offload features can be disabled in Windows' network adapter properties page.
      </para></listitem>
    </itemizedlist>
  </sect2>

  <sect2 id="npcap-issues">
    <title>Reporting Bugs</title>

    <para>
      Please report any bugs or issues about Npcap on
      <ulink role="hidepdf" url="http://issues.npcap.org/new?title=Npcap+Bug+Report">the Nmap Project's Issues tracker</ulink>.
      In your report, please provide your <emphasis>DiagReport</emphasis> output, user
      software version (e.g. Nmap, Wireshark), steps to reproduce the problem, and other information
      you think necessary. If your issue occurs only on a particular OS version (e.g. Win10
      1511, 1607), please mention it in the report.
    </para>

    <sect3 id="npcap-issues-diagreport">
      <title>Diagnostic report</title>

      <para>
        Npcap has provided a diagnostic utility called <filename>DiagReport</filename>.
        It provides a lot of information including OS metadata, Npcap related files,
        install options, registry values, services, etc. You can simply click the
        <filename>C:\Program Files\Npcap\DiagReport.bat</filename> file to run <filename>DiagReport</filename>.
        It will pop up a text report via Notepad (it's stored in: <filename>C:\Program Files\Npcap\DiagReport.txt</filename>).
        Please always submit it to us if you encounter any issues.
      </para>

    </sect3>
    <sect3 id="npcap-issues-installation-log">
      <title>General installation log</title>

      <para>
        Npcap keeps track of the installation in a log file:
        <filename>C:\Program Files\Npcap\install.log</filename>. Please submit it
        together in your report if you encounter issues during the installation
        (e.g. the installer halts).
      </para>
    </sect3>

    <sect3 id="npcap-issues-driver-installation-log">
      <title>Driver installation log</title>

      <para>
        Npcap keeps track of the driver installation (aka commands run by
        <filename>NPFInstall.exe</filename>) in a log file:
        <filename>C:\Program Files\Npcap\NPFInstall.log</filename>, please submit
        it together in your report if you encounter issues during the driver
        installation or problems with the <quote>Npcap Loopback Adapter</quote>.
      </para>

      <para>
        There's another system-provided driver installation log in:
        <filename>C:\Windows\INF\setupapi.dev.log</filename>.
        If you encounter errors during the driver/service installation, please copy
        the Npcap-related lines out and send them together in
        your report.
      </para>
    </sect3>

    <sect3 id="npcap-issues-packet-log">
      <title>Dynamic link library (DLL) log</title>

      <para>
        For problems with Npcap's regular operation, you may need to obtain a
        debug log from <filename>Packet.dll</filename>.  To do this, you will
        need a debug build of Npcap.  If you are a Npcap developer, you can build
        the <filename>Packet.sln</filename> project with the
        <varname>_DEBUG_TO_FILE</varname> macro defined. If you are an end user,
        you can contact the Npcap development team for the latest Npcap debug
        build.  The debugging process will continue to append to the debug log
        (<filename>C:\Program Files\Npcap\Packet.log</filename>), so you may want
        to delete it after an amount of time, or save your output to another
        place before it gets too large.
      </para>
    </sect3>

    <sect3 id="npcap-issues-driver-log">
      <title>Driver log</title>

      <para>
        If there is an issue with the Npcap driver, you can open an
        <emphasis>Administrator</emphasis> command prompt,  enter <command>sc query
          npcap</command> to query the driver status and <command>net start
          npcap</command> to start the driver. The command
        output will inform you whether there's an error. If the driver is running
        well, but the issue still exists, then you may need to check the driver's
        log. Normal Npcap releases don't switch on the driver log function for
        performance. Contact the Npcap development team to obtain a driver-debug
        version of the Npcap installer.  When you have got an appropriate
        driver-debug version Npcap, you need to use <ulink role="hidepdf"
          url="https://technet.microsoft.com/en-us/sysinternals/debugview.aspx">DbgView</ulink>
        to read the Windows kernel log (which contains our driver log).  You may
        need to turn on DbgView before installing Npcap, if the error occurs when
        the driver loads. When done, save the DbgView output to a file and submit
        it in your report.
      </para>
    </sect3>
    <sect3 id="npcap-issues-bsod">
      <title>Blue screen of death (BSoD) dump</title>

      <para>
        If you encountered BSoD when using Npcap, please attach the minidump
        file (in <filename>C:\Windows\Minidump\</filename>) to your report
        together with the Npcap version. We may ask you to provide the full
        dump (<filename>C:\Windows\MEMORY.DMP</filename>) for further troubleshooting.
      </para>
    </sect3>
  </sect2>

</sect1>
