kea/doc/guide/bind10-guide.xml

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 - Copyright (C) 2010-2011  Internet Systems Consortium, Inc. ("ISC")
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 - Permission to use, copy, modify, and/or distribute this software for any
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 - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 - PERFORMANCE OF THIS SOFTWARE.
-->

<book>
  <?xml-stylesheet href="bind10-guide.css" type="text/css"?>

  <bookinfo>
    <title>BIND 10 Guide</title>
    <subtitle>Administrator Reference for BIND 10</subtitle>

    <copyright>
      <year>2010-2011</year><holder>Internet Systems Consortium, Inc.</holder>
    </copyright>

    <abstract>
      <para>BIND 10 is a Domain Name System (DNS) suite managed by
        Internet Systems Consortium (ISC). It includes DNS libraries
        and modular components for controlling authoritative and
        recursive DNS servers.
      </para>
      <para>
        This is the reference guide for BIND 10 version &__VERSION__;.
        The most up-to-date version of this document (in PDF, HTML,
        and plain text formats), along with other documents for
        BIND 10, can be found at <ulink url="http://bind10.isc.org/docs"/>.
        </para> </abstract>

      <releaseinfo>This is the reference guide for BIND 10 version
        &__VERSION__;.</releaseinfo>

  </bookinfo>

  <chapter id="intro">
    <title>Introduction</title>
    <para>
      BIND is the popular implementation of a DNS server, developer
      interfaces, and DNS tools.
      BIND 10 is a rewrite of BIND 9.  BIND 10 is written in C++ and Python
      and provides a modular environment for serving and maintaining DNS.
    </para>

    <note>
      <para>
        This guide covers the experimental prototype of
        BIND 10 version &__VERSION__;.
      </para>
    </note>

    <note>
      <para>
        BIND 10 provides a EDNS0- and DNSSEC-capable
        authoritative DNS server and a caching recursive name server
        which also provides forwarding.
      </para>
    </note>

    <section>
      <title>Supported Platforms</title>
      <para>
  BIND 10 builds have been tested on Debian GNU/Linux 5,
  Ubuntu 9.10, NetBSD 5, Solaris 10, FreeBSD 7 and 8, and CentOS
  Linux 5.3.

  It has been tested on Sparc, i386, and amd64 hardware
  platforms.

        It is planned for BIND 10 to build, install and run on
        Windows and standard Unix-type platforms.
      </para>
    </section>

    <section>
      <title>Required Software</title>
      <para>
        BIND 10 requires Python 3.1.  Later versions may work, but Python
        3.1 is the minimum version which will work.
      </para>

      <para>
        BIND 10 uses the Botan crypto library for C++. It requires
        at least Botan version 1.8.
      </para>

      <para>
        BIND 10 uses the log4cplus C++ logging library. It requires
        at least log4cplus version 1.0.3.
      </para>

      <para>
        The authoritative server requires SQLite 3.3.9 or newer.
        The <command>b10-xfrin</command>, <command>b10-xfrout</command>,
        and <command>b10-zonemgr</command> modules require the
        libpython3 library and the Python _sqlite3.so module.
      </para>
<!-- TODO: this will change ... -->

<!-- TODO: list where to get these from -->

      <note>
        <para>
          Some operating systems do not provide these dependencies
          in their default installation nor standard packages
          collections.
          You may need to install them separately.
        </para>
      </note>
    </section>

    <section id="starting_stopping">
      <title>Starting and Stopping the Server</title>

      <para>
        BIND 10 is modular.  Part of this modularity is
        accomplished using multiple cooperating processes which, together,
        provide the server functionality.  This is a change from
        the previous generation of BIND software, which used a
        single process.
      </para>

      <para>
        At first, running many different processes may seem confusing.
        However, these processes are started, stopped, and maintained
        by a single command, <command>bind10</command>.
        This command starts a master process which will start other
        processes as needed.
        The processes started by the <command>bind10</command>
        command have names starting with "b10-", including:
      </para>

      <para>

        <itemizedlist>

          <listitem>
            <simpara>
              <command>b10-msgq</command> &mdash;
              Message bus daemon.
              This process coordinates communication between all of the other
              BIND 10 processes.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>b10-auth</command> &mdash;
              Authoritative DNS server.
              This process serves DNS requests.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>b10-cfgmgr</command> &mdash;
              Configuration manager.
              This process maintains all of the configuration for BIND 10.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>b10-cmdctl</command> &mdash;
              Command and control service.
              This process allows external control of the BIND 10 system.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>b10-resolver</command> &mdash;
              Recursive name server.
              This process handles incoming queries.
<!-- TODO: -->
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>b10-stats</command> &mdash;
              Statistics collection daemon.
              This process collects and reports statistics data.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>b10-xfrin</command> &mdash;
              Incoming zone transfer service.
              This process is used to transfer a new copy
              of a zone into BIND 10, when acting as a secondary server.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>b10-xfrout</command> &mdash;
              Outgoing zone transfer service.
              This process is used to handle transfer requests to
              send a local zone to a remote secondary server,
              when acting as a master server.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>b10-zonemgr</command> &mdash;
              Secondary manager.
              This process keeps track of timers and other
              necessary information for BIND 10 to act as a slave server.
            </simpara>
          </listitem>

        </itemizedlist>
      </para>

      <para>
        These are ran automatically by <command>bind10</command>
        and do not need to be run manually.
      </para>

    </section>

    <section id="managing_once_running">
      <title>Managing BIND 10</title>

      <para>
        Once BIND 10 is running, a few commands are used to interact
        directly with the system:
        <itemizedlist>
          <listitem>
            <simpara>
              <command>bindctl</command> &mdash;
              interactive administration interface.
              This is a command-line tool which allows an administrator
              to control BIND 10.
            </simpara>
          </listitem>
          <listitem>
            <simpara>
              <command>b10-loadzone</command> &mdash;
              zone file loader.
              This tool will load standard masterfile-format zone files into
              BIND 10.
            </simpara>
          </listitem>
          <listitem>
            <simpara>
              <command>b10-cmdctl-usermgr</command> &mdash;
              user access control.
              This tool allows an administrator to authorize additional users
              to manage BIND 10.
            </simpara>
          </listitem>
  <!-- TODO usermgr -->
        </itemizedlist>
      </para>
    </section>

    <para>
      The tools and modules are covered in full detail in this guide.
<!-- TODO point to these -->
      In addition, manual pages are also provided in the default installation.
    </para>

<!--
bin/
  bindctl*
  host*
lib/
  libauth
  libdns
  libexceptions
  python3.1/site-packages/isc/{cc,config}
sbin/
  bind10
share/
  share/bind10/
    auth.spec
    b10-cmdctl.pem
    bob.spec
    passwd.csv
  man/
var/
  bind10/b10-config.db
-->

    <para>
      BIND 10 also provides libraries and programmer interfaces
      for C++ and Python for the message bus, configuration backend,
      and, of course, DNS. These include detailed developer
      documentation and code examples.
<!-- TODO point to this -->
    </para>

  </chapter>

  <chapter id="installation">
    <title>Installation</title>

    <section>
      <title>Building Requirements</title>

        <para>
          In addition to the run-time requirements, building BIND 10
          from source code requires various development include headers.
        </para>

        <note>
          <simpara>
            Some operating systems have split their distribution packages into
            a run-time and a development package.  You will need to install
            the development package versions, which include header files and
            libraries, to build BIND 10 from source code.
          </simpara>
        </note>

        <para>
          Building from source code requires the Boost
          build-time headers. At least Boost version 1.35 is required.
  <!-- TODO: we don't check for this version -->
  <!-- NOTE: jreed has tested with 1.34, 1.38, and 1.41. -->
        </para>

        <para>
          To build BIND 10, also install the Botan (at least version
          1.8) and the log4cplus (at least version 1.0.3)
          development include headers.
        </para>

<!--
TODO
Debian and Ubuntu:
 libgmp3-dev and libbz2-dev required for botan too
-->

        <para>
<!-- TODO: is this needed at build time? test time? -->
          The Python Library and Python _sqlite3 module are required to
          enable the Xfrout and Xfrin support.
        </para>

        <note><simpara>
          The Python related libraries and modules need to be built
          for Python 3.1.
        </simpara></note>

        <para>
          Building BIND 10 also requires a C++ compiler and
          standard development headers, make, and pkg-config.
          BIND 10 builds have been tested with GCC g++ 3.4.3, 4.1.2,
          4.1.3, 4.2.1, 4.3.2, and 4.4.1; Clang++ 2.8; and Sun C++ 5.10.
        </para>
    </section>

    <section id="quickstart">
      <title>Quick start</title>
      <note>
        <simpara>
          This quickly covers the standard steps for installing
          and deploying BIND 10 as an authoritative name server using
          its defaults. For troubleshooting, full customizations and further
          details, see the respective chapters in the BIND 10 guide.
        </simpara>
      </note>

      <para>
        To quickly get started with BIND 10, follow these steps.
      </para>

      <orderedlist>

        <listitem>
          <simpara>
            Install required build dependencies.
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            Download the BIND 10 source tar file from
            <ulink url="ftp://ftp.isc.org/isc/bind10/"/>.
          </simpara>
        </listitem>

        <listitem>
          <para>Extract the tar file:
          <screen>$ <userinput>gzcat bind10-<replaceable>VERSION</replaceable>.tar.gz | tar -xvf -</userinput></screen>
          </para>
        </listitem>

        <listitem>
          <para>Go into the source and run configure:
            <screen>$ <userinput>cd bind10-<replaceable>VERSION</replaceable></userinput>
  $ <userinput>./configure</userinput></screen>
          </para>
        </listitem>

        <listitem>
          <para>Build it:
            <screen>$ <userinput>make</userinput></screen>
          </para>
        </listitem>

        <listitem>
          <para>Install it (to default /usr/local):
            <screen>$ <userinput>make install</userinput></screen>
          </para>
        </listitem>

        <listitem>
          <para>Start the server:
            <screen>$ <userinput>/usr/local/sbin/bind10</userinput></screen>
          </para>
        </listitem>

        <listitem>

         <para>Test it; for example:
            <screen>$ <userinput>dig @127.0.0.1 -c CH -t TXT authors.bind</userinput></screen>
         </para>
        </listitem>

        <listitem>
          <para>Load desired zone file(s), for example:
            <screen>$ <userinput>b10-loadzone <replaceable>your.zone.example.org</replaceable></userinput></screen>
          </para>
        </listitem>

        <listitem>
          <simpara>
            Test the new zone.
          </simpara>
        </listitem>

      </orderedlist>

    </section>

    <section id="install">
      <title>Installation from source</title>
      <para>
        BIND 10 is open source software written in C++ and Python.
        It is freely available in source code form from ISC via
        the Git code revision control system or as a downloadable
        tar file. It may also be available in pre-compiled ready-to-use
        packages from operating system vendors.
      </para>

      <section>
        <title>Download Tar File</title>
        <para>
          Downloading a release tar file is the recommended method to
          obtain the source code.
        </para>

        <para>
          The BIND 10 releases are available as tar file downloads from
          <ulink url="ftp://ftp.isc.org/isc/bind10/"/>.
          Periodic development snapshots may also be available.
        </para>
  <!-- TODO -->
      </section>

      <section>
        <title>Retrieve from Git</title>
        <para>
          Downloading this "bleeding edge" code is recommended only for
          developers or advanced users.  Using development code in a production
          environment is not recommended.
        </para>

        <note>
          <para>
            When using source code retrieved via Git additional
            software will be required:  automake (v1.11 or newer),
            libtoolize, and autoconf (2.59 or newer).
            These may need to be installed.
          </para>
        </note>

        <para>
          The latest development code, including temporary experiments
          and un-reviewed code, is available via the BIND 10 code revision
          control system. This is powered by Git and all the BIND 10
          development is public.
          The leading development is done in the <quote>master</quote>.
        </para>
        <para>
          The code can be checked out from
          <filename>git://bind10.isc.org/bind10</filename>;
          for example:

        <screen>$ <userinput>git clone git://bind10.isc.org/bind10</userinput></screen>
        </para>

        <para>
          When checking out the code from
          the code version control system, it doesn't include the
          generated configure script, Makefile.in files, nor the
          related configure files.
          They can be created by running <command>autoreconf</command>
          with the <option>--install</option> switch.
          This will run <command>autoconf</command>,
          <command>aclocal</command>,
          <command>libtoolize</command>,
          <command>autoheader</command>,
          <command>automake</command>,
          and related commands.
        </para>

      </section>


      <section>
        <title>Configure before the build</title>
        <para>
          BIND 10 uses the GNU Build System to discover build environment
          details.
          To generate the makefiles using the defaults, simply run:
          <screen>$ <userinput>./configure</userinput></screen>
        </para>
        <para>
          Run <command>./configure</command> with the <option>--help</option>
          switch to view the different options. The commonly-used options are:

          <variablelist>

          <varlistentry>
            <term>--prefix</term>
            <listitem>
              <simpara>Define the installation location (the
                default is <filename>/usr/local/</filename>).
              </simpara>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>--with-boost-include</term>
            <listitem>
              <simpara>Define the path to find the Boost headers.
              </simpara>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>--with-pythonpath</term>
            <listitem>
              <simpara>Define the path to Python 3.1 if it is not in the
                standard execution path.
              </simpara>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>--with-gtest</term>
            <listitem>
              <simpara>Enable building the C++ Unit Tests using the
                Google Tests framework. Optionally this can define the
                path to the gtest header files and library.
              </simpara>
            </listitem>
          </varlistentry>

          </variablelist>

        </para>
  <!-- TODO: lcov -->

        <para>
          For example, the following configures it to
    find the Boost headers, find the
    Python interpreter, and sets the installation location:

          <screen>$ <userinput>./configure \
      --with-boost-include=/usr/pkg/include \
      --with-pythonpath=/usr/pkg/bin/python3.1 \
      --prefix=/opt/bind10</userinput></screen>
        </para>

        <para>
          If the configure fails, it may be due to missing or old
          dependencies.
        </para>

      </section>

      <section>
        <title>Build</title>
        <para>
    After the configure step is complete, to build the executables
    from the C++ code and prepare the Python scripts, run:

          <screen>$ <userinput>make</userinput></screen>
        </para>
      </section>

      <section>
        <title>Install</title>
        <para>
          To install the BIND 10 executables, support files,
          and documentation, run:
          <screen>$ <userinput>make install</userinput></screen>
        </para>
        <note>
          <para>The install step may require superuser privileges.</para>
        </note>

      </section>

  <!-- TODO: tests -->

      <section>
        <title>Install Hierarchy</title>
        <para>
          The following is the layout of the complete BIND 10 installation:
          <itemizedlist>
            <listitem>
              <simpara>
                <filename>bin/</filename> &mdash;
                general tools and diagnostic clients.
              </simpara>
            </listitem>
            <listitem>
            <simpara>
              <filename>etc/bind10-devel/</filename> &mdash;
              configuration files.
            </simpara>
            </listitem>
            <listitem>
              <simpara>
                <filename>lib/</filename> &mdash;
                libraries and python modules.
              </simpara>
            </listitem>
            <listitem>
              <simpara>
                <filename>libexec/bind10-devel/</filename> &mdash;
                executables that a user wouldn't normally run directly and
                are not run independently.
                These are the BIND 10 modules which are daemons started by
                the <command>bind10</command> tool.
              </simpara>
            </listitem>
            <listitem>
              <simpara>
                <filename>sbin/</filename> &mdash;
                commands used by the system administrator.
              </simpara>
            </listitem>
            <listitem>
              <simpara>
                <filename>share/bind10-devel/</filename> &mdash;
                configuration specifications.
              </simpara>
            </listitem>
            <listitem>
              <simpara>
                <filename>share/man/</filename> &mdash;
                manual pages (online documentation).
              </simpara>
            </listitem>
            <listitem>
              <simpara>
                <filename>var/bind10-devel/</filename> &mdash;
                data source and configuration databases.
              </simpara>
            </listitem>
          </itemizedlist>
        </para>
      </section>
    </section>

  <!--
      <section id="install.troubleshooting">
        <title>Troubleshooting</title>
        <para>
        </para>
      </section>
  -->

  </chapter>

  <chapter id="bind10">
    <title>Starting BIND10 with <command>bind10</command></title>
    <para>
      BIND 10 provides the <command>bind10</command> command which
      starts up the required processes.
      <command>bind10</command>
      will also restart some processes that exit unexpectedly.
      This is the only command needed to start the BIND 10 system.
    </para>

    <para>
      After starting the <command>b10-msgq</command> communications channel,
      <command>bind10</command> connects to it,
      runs the configuration manager, and reads its own configuration.
      Then it starts the other modules.
    </para>

    <para>
      The <command>b10-sockcreator</command>, <command>b10-msgq</command> and
      <command>b10-cfgmgr</command>
      services make up the core. The <command>b10-msgq</command> daemon
      provides the communication channel between every part of the system.
      The <command>b10-cfgmgr</command> daemon is always needed by every
      module, if only to send information about themselves somewhere,
      but more importantly to ask about their own settings, and
      about other modules. The <command>b10-sockcreator</command> will
      allocate sockets for the rest of the system.
    </para>

    <para>
      In its default configuration, the <command>bind10</command>
      master process will also start up
      <command>b10-cmdctl</command> for admins to communicate with the
      system, <command>b10-auth</command> for authoritative DNS service,
      <command>b10-stats</command> for statistics collection,
      <command>b10-xfrin</command> for inbound DNS zone transfers,
      <command>b10-xfrout</command> for outbound DNS zone transfers,
      and <command>b10-zonemgr</command> for secondary service.
    </para>

    <section id="start">
      <title>Starting BIND 10</title>
      <para>
        To start the BIND 10 service, simply run <command>bind10</command>.
        Run it with the <option>--verbose</option> switch to
        get additional debugging or diagnostic output.
      </para>
<!-- TODO: note it doesn't go into background -->

      <note>
        <para>
          If the setproctitle Python module is detected at start up,
          the process names for the Python-based daemons will be renamed
          to better identify them instead of just <quote>python</quote>.
          This is not needed on some operating systems.
        </para>
      </note>

    </section>
    <section id="bind10.config">
      <title>Configuration of started processes</title>
      <para>
        The processes to be started can be configured, with the exception
        of the <command>b10-sockcreator</command>, <command>b10-msgq</command>
        and <command>b10-cfgmgr</command>.
      </para>

      <para>
        The configuration is in the Boss/components section. Each element
        represents one component, which is an abstraction of a process
        (currently there's also one component which doesn't represent
        a process). If you didn't want to transfer out at all (your server
        is a slave only), you would just remove the corresponding component
        from the set, like this and the process would be stopped immediately
        (and not started on the next startup):
      <screen>&gt; <userinput>config remove Boss/components b10-xfrout</userinput>
&gt; <userinput>config commit</userinput></screen>
      </para>

      <para>
        To add a process to the set, let's say the resolver (which not started
        by default), you would do this:
        <screen>&gt; <userinput>config add Boss/components b10-resolver</userinput>
&gt; <userinput>config set Boss/components/b10-resolver/special resolver</userinput>
&gt; <userinput>config set Boss/components/b10-resolver/kind needed</userinput>
&gt; <userinput>config set Boss/components/b10-resolver/priority 10</userinput>
&gt; <userinput>config commit</userinput></screen></para>

      <para>
        Now, what it means. We add an entry called b10-resolver. It is both a
        name used to reference this component in the configuration and the
        name of the process to start. Then we set some parameters on how to
        start it.
      </para>

      <para>
        The special one is for components that need some kind of special care
        during startup or shutdown. Unless specified, the component is started
        in usual way. This is the list of components that need to be started
        in a special way, with the value of special used for them:
        <table>
          <tgroup cols='3' align='left'>
          <colspec colname='component'/>
          <colspec colname='special'/>
          <colspec colname='description'/>
          <thead><row><entry>Component</entry><entry>Special</entry><entry>Description</entry></row></thead>
          <tbody>
            <row><entry>b10-auth</entry><entry>auth</entry><entry>Authoritative server</entry></row>
            <row><entry>b10-resolver</entry><entry>resolver</entry><entry>The resolver</entry></row>
            <row><entry>b10-cmdctl</entry><entry>cmdctl</entry><entry>The command control (remote control interface)</entry></row>
            <row><entry>setuid</entry><entry>setuid</entry><entry>Virtual component, see below</entry></row>
            <!-- TODO Either add xfrin and xfrout as well or clean up the workarounds in boss before the release -->
          </tbody>
          </tgroup>
        </table>
      </para>

      <para>
        The kind specifies how a failure of the component should
        be handled.  If it is set to <quote>dispensable</quote>
        (the default unless you set something else), it will get
        started again if it fails. If it is set to <quote>needed</quote>
        and it fails at startup, the whole <command>bind10</command>
        shuts down and exits with error exit code. But if it fails
        some time later, it is just started again. If you set it
        to <quote>core</quote>, you indicate that the system is
        not usable without the component and if such component
        fails, the system shuts down no matter when the failure
        happened.  This is the behaviour of the core components
        (the ones you can't turn off), but you can declare any
        other components as core as well if you wish (but you can
        turn these off, they just can't fail).
      </para>

      <para>
        The priority defines order in which the components should start.
        The ones with higher number are started sooner than the ones with
        lower ones. If you don't set it, 0 (zero) is used as the priority.
      </para>

      <para>
        There are other parameters we didn't use in our example.
        One of them is <quote>address</quote>. It is the address
        used by the component on the <command>b10-msgq</command>
        message bus. The special components already know their
        address, but the usual ones don't. The address is by
        convention the thing after <emphasis>b10-</emphasis>, with
        the first letter capital (eg. <command>b10-stats</command>
        would have <quote>Stats</quote> as its address).
<!-- TODO: this should be simplified so we don't even have to document it -->
      </para>

<!-- TODO: what does "The special components already know their
address, but the usual ones don't." mean? -->

<!-- TODO: document params when is enabled -->

      <para>
        The last one is process. It is the name of the process to be started.
        It defaults to the name of the component if not set, but you can use
        this to override it.
      </para>

      <!-- TODO Add parameters when they work, not implemented yet-->

      <note>
        <para>
          This system allows you to start the same component multiple times
          (by including it in the configuration with different names, but the
          same process setting). However, the rest of the system doesn't expect
          such situation, so it would probably not do what you want. Such
          support is yet to be implemented.
        </para>
      </note>

      <note>
        <para>
          The configuration is quite powerful, but that includes
          a lot of space for mistakes. You could turn off the
          <command>b10-cmdctl</command>, but then you couldn't
          change it back the usual way, as it would require it to
          be running (you would have to find and edit the configuration
          directly).  Also, some modules might have dependencies
          -- <command>b10-stats-httpd</command> need
          <command>b10-stats</command>, <command>b10-xfrout</command>
          needs the <command>b10-auth</command> to be running, etc.

<!-- TODO: should we define dependencies? -->

        </para>
        <para>
          In short, you should think twice before disabling something here.
        </para>
      </note>

      <para>
        Now, to the mysterious setuid virtual component. If you
        use the <command>-u</command> option to start the
        <command>bind10</command> as root, but change the user
        later, we need to start the <command>b10-auth</command> or
        <command>b10-resolver</command> as root (until the socket
        creator is finished).<!-- TODO --> So we need to specify
        the time when the switch from root do the given user happens
        and that's what the setuid component is for. The switch is
        done at the time the setuid component would be started, if
        it was a process. The default configuration contains the
        setuid component with priority 5, <command>b10-auth</command>
        has 10 to be started before the switch and everything else
        is without priority, so it is started after the switch.
      </para>

    </section>

  </chapter>

  <chapter id="msgq">
    <title>Command channel</title>

      <para>
        The BIND 10 components use the <command>b10-msgq</command>
        message routing daemon to communicate with other BIND 10 components.
        The <command>b10-msgq</command> implements what is called the
        <quote>Command Channel</quote>.
        Processes intercommunicate by sending messages on the command
        channel.
        Example messages include shutdown, get configurations, and set
        configurations.
        This Command Channel is not used for DNS message passing.
        It is used only to control and monitor the BIND 10 system.
      </para>

      <para>
        Administrators do not communicate directly with the
        <command>b10-msgq</command> daemon.
        By default, BIND 10 uses port 9912 for the
        <command>b10-msgq</command> service.
        It listens on 127.0.0.1.
      </para>

<!-- TODO: this is broken, see Trac #111
      <para>
        To select an alternate port for the <command>b10-msgq</command> to
        use, run <command>bind10</command> specifying the option:
        <screen> $ <userinput>bind10 -TODO-msgq-port 9912</userinput></screen>
      </para>
-->

<!-- TODO: upcoming plans:
Unix domain sockets
-->

  </chapter>

  <chapter id="cfgmgr">
    <title>Configuration manager</title>

      <para>
         The configuration manager, <command>b10-cfgmgr</command>,
         handles all BIND 10 system configuration.  It provides
         persistent storage for configuration, and notifies running
         modules of configuration changes.
      </para>

      <para>
        The <command>b10-auth</command> and <command>b10-xfrin</command>
        daemons and other components receive their configurations
        from the configuration manager over the <command>b10-msgq</command>
        command channel.
      </para>

      <para>The administrator doesn't connect to it directly, but
        uses a user interface to communicate with the configuration
        manager via <command>b10-cmdctl</command>'s REST-ful interface.
        <command>b10-cmdctl</command> is covered in <xref linkend="cmdctl"/>.
      </para>

<!-- TODO -->
      <note>
        <para>
          The development prototype release only provides the
          <command>bindctl</command> as a user interface to
          <command>b10-cmdctl</command>.
          Upcoming releases will provide another interactive command-line
          interface and a web-based interface.
        </para>
      </note>

      <para>
        The <command>b10-cfgmgr</command> daemon can send all
        specifications and all current settings to the
        <command>bindctl</command> client (via
        <command>b10-cmdctl</command>).
      </para>

      <para>
        <command>b10-cfgmgr</command> relays configurations received
        from <command>b10-cmdctl</command> to the appropriate modules.
      </para>
<!-- TODO:
        Configuration settings for itself are defined as ConfigManager.
TODO: show examples
-->

<!-- TODO:
config changes are actually commands to cfgmgr
-->

<!-- TODO: what about run time config to change this? -->
<!-- jelte: > config set cfgmgr/config_database <file> -->
<!-- TODO: what about command line switch to change this? -->
      <para>
        The stored configuration file is at
        <filename>/usr/local/var/bind10-devel/b10-config.db</filename>.
        (The full path is what was defined at build configure time for
        <option>--localstatedir</option>.
        The default is <filename>/usr/local/var/</filename>.)
        The format is loosely based on JSON and is directly parseable
        python, but this may change in a future version.
        This configuration data file is not manually edited by the
        administrator.
      </para>

<!--

Well the specfiles have a more fixed format (they must contain specific
stuff), but those are also directly parseable python structures (and
'coincidentally', our data::element string representation is the same)

loosely based on json, tweaked to be directly parseable in python, but a
subset of that.
wiki page is http://bind10.isc.org/wiki/DataElementDesign

nope, spec files are written by module developers, and db should be done
through bindctl and friends

-->

    <para>
      The configuration manager does not have any command line arguments.
      Normally it is not started manually, but is automatically
      started using the <command>bind10</command> master process
      (as covered in <xref linkend="bind10"/>).
    </para>

<!-- TODO: upcoming plans:
configuration for configuration manager itself. And perhaps we might
change the messaging protocol, but an admin should never see any of that
-->

<!-- TODO: show examples, test this -->
<!--
, so an admin can simply run bindctl,
do config show, and it shows all modules; config show >module> shows all
options for that module
-->

  </chapter>

  <chapter id="cmdctl">
    <title>Remote control daemon</title>

    <para>
      <command>b10-cmdctl</command> is the gateway between
      administrators and the BIND 10 system.
      It is a HTTPS server that uses standard HTTP Digest
      Authentication for username and password validation.
      It provides a REST-ful interface for accessing and controlling
      BIND 10.
    </para>
<!-- TODO: copy examples from wiki, try with wget -->

    <para>
      When <command>b10-cmdctl</command> starts, it firsts
      asks <command>b10-cfgmgr</command> about what modules are
      running and what their configuration is (over the
      <command>b10-msgq</command> channel). Then it will start listening
      on HTTPS for clients &mdash; the user interface &mdash; such
      as <command>bindctl</command>.
    </para>

    <para>
      <command>b10-cmdctl</command> directly sends commands
      (received from the user interface) to the specified component.
      Configuration changes are actually commands to
      <command>b10-cfgmgr</command> so are sent there.
    </para>

<!--
TODO:
"For bindctl to list a module's available configurations and
available commands, it communicates over the cmdctl REST interface.
cmdctl then asks cfgmgr over the msgq command channel. Then cfgmgr
asks the module for its specification and also cfgmgr looks in its
own configuration database for current values."

(05:32:03) jelte: i think cmdctl doesn't request it upon a incoming
GET, but rather requests it once and then listens in for updates,
but you might wanna check with likun
-->

<!-- TODO: replace /usr/local -->
<!-- TODO: permissions -->
    <para>The HTTPS server requires a private key,
      such as a RSA PRIVATE KEY.
      The default location is at
      <filename>/usr/local/etc/bind10-devel/cmdctl-keyfile.pem</filename>.
      (A sample key is at
      <filename>/usr/local/share/bind10-devel/cmdctl-keyfile.pem</filename>.)
      It also uses a certificate located at
      <filename>/usr/local/etc/bind10-devel/cmdctl-certfile.pem</filename>.
      (A sample certificate is at
      <filename>/usr/local/share/bind10-devel/cmdctl-certfile.pem</filename>.)
      This may be a self-signed certificate or purchased from a
      certification authority.
    </para>

    <note><para>
      The HTTPS server doesn't support a certificate request from a
      client (at this time).
<!-- TODO: maybe allow request from server side -->
      The <command>b10-cmdctl</command> daemon does not provide a
      public service. If any client wants to control BIND 10, then
      a certificate needs to be first received from the BIND 10
      administrator.
      The BIND 10 installation provides a sample PEM bundle that matches
      the sample key and certificate.
    </para></note>
<!-- TODO: cross-ref -->

<!-- TODO
openssl req -new -x509 -keyout server.pem -out server.pem -days 365 -nodes
but that is a single file, maybethis should go back to that format?
-->

<!--
    <para>
(08:20:56) shane: It is in theory possible to run without cmdctl.
(08:21:02) shane: I think we discussed this.
    </para>
-->

<!-- TODO: Please check https://bind10.isc.org/wiki/cmd-ctrld -->


    <para>
      The <command>b10-cmdctl</command> daemon also requires
      the user account file located at
      <filename>/usr/local/etc/bind10-devel/cmdctl-accounts.csv</filename>.
      This comma-delimited file lists the accounts with a user name,
      hashed password, and salt.
      (A sample file is at
      <filename>/usr/local/share/bind10-devel/cmdctl-accounts.csv</filename>.
      It contains the user named <quote>root</quote> with the password
      <quote>bind10</quote>.)
    </para>

    <para>
      The administrator may create a user account with the
      <command>b10-cmdctl-usermgr</command> tool.
    </para>
<!-- TODO: show example -->

<!-- TODO: does cmdctl need to be restarted to change cert or key
or accounts database -->

    <para>
      By default the HTTPS server listens on the localhost port 8080.
      The port can be set by using the <option>--port</option> command line option.
      The address to listen on can be set using the <option>--address</option> command
      line argument.
      Each HTTPS connection is stateless and timesout in 1200 seconds
      by default.  This can be
      redefined by using the <option>--idle-timeout</option> command line argument.
    </para>

    <section id="cmdctl.spec">
      <title>Configuration specification for b10-cmdctl</title>
      <para>
        The configuration items for <command>b10-cmdctl</command> are:
key_file
cert_file
accounts_file
      </para>
<!-- TODO -->

      <para>
        The control commands are:
print_settings
<!-- TODO: remove that -->

shutdown
      </para>
<!-- TODO -->
    </section>

<!--
TODO
(12:21:30) jinmei: I'd like to have sample session using a command line www client such as wget
(12:21:33) jinmei: btw
-->

  </chapter>

  <chapter id="bindctl">
    <title>Control and configure user interface</title>

    <note><para>
      For this development prototype release, <command>bindctl</command>
      is the only user interface. It is expected that upcoming
      releases will provide another interactive command-line
      interface and a web-based interface for controlling and
      configuring BIND 10.
    </para></note>

    <para>
      The <command>bindctl</command> tool provides an interactive
      prompt for configuring, controlling, and querying the BIND 10
      components.
      It communicates directly with a REST-ful interface over HTTPS
      provided by <command>b10-cmdctl</command>. It doesn't
      communicate to any other components directly.
    </para>

<!-- TODO: explain and show interface -->

    <para>
      Configuration changes are actually commands to
      <command>b10-cfgmgr</command>. So when <command>bindctl</command>
      sends a configuration, it is sent to <command>b10-cmdctl</command>
      (over a HTTPS connection); then <command>b10-cmdctl</command>
      sends the command (over a <command>b10-msgq</command> command
      channel) to <command>b10-cfgmgr</command> which then stores
      the details and relays (over a <command>b10-msgq</command> command
      channel) the configuration on to the specified module.
    </para>

    <para>
    </para>

  </chapter>

  <chapter id="authserver">
    <title>Authoritative Server</title>

    <para>
      The <command>b10-auth</command> is the authoritative DNS server.
      It supports EDNS0 and DNSSEC. It supports IPv6.
      Normally it is started by the <command>bind10</command> master
      process.
    </para>

    <section>
      <title>Server Configurations</title>

<!-- TODO: offers command line options but not used
since we used bind10 -->

      <para>
        <command>b10-auth</command> is configured via the
        <command>b10-cfgmgr</command> configuration manager.
        The module name is <quote>Auth</quote>.
        The configuration data item is:

        <variablelist>

          <varlistentry>
            <term>database_file</term>
            <listitem>
              <simpara>This is an optional string to define the path to find
                 the SQLite3 database file.
<!-- TODO: -->
Note: Later the DNS server will use various data source backends.
This may be a temporary setting until then.
              </simpara>
            </listitem>
          </varlistentry>

        </variablelist>

      </para>

      <para>

        The configuration command is:

        <variablelist>

          <varlistentry>
            <term>shutdown</term>
            <listitem>
              <simpara>Stop the authoritative DNS server.
              </simpara>
<!-- TODO: what happens when this is sent, will bind10 restart? -->
            </listitem>
          </varlistentry>

        </variablelist>

      </para>

<!-- TODO: examples of setting or running above? -->

    </section>

    <section>
      <title>Data Source Backends</title>

      <note><para>
        For the development prototype release, <command>b10-auth</command>
        supports a SQLite3 data source backend and in-memory data source
        backend.
        Upcoming versions will be able to use multiple different
        data sources, such as MySQL and Berkeley DB.
      </para></note>


      <para>
        By default, the SQLite3 backend uses the data file located at
        <filename>/usr/local/var/bind10-devel/zone.sqlite3</filename>.
        (The full path is what was defined at build configure time for
        <option>--localstatedir</option>.
        The default is <filename>/usr/local/var/</filename>.)
  This data file location may be changed by defining the
  <quote>database_file</quote> configuration.
      </para>

    </section>

    <section>
      <title>Loading Master Zones Files</title>

      <para>
        RFC 1035 style DNS master zone files may imported
        into a BIND 10 data source by using the
        <command>b10-loadzone</command> utility.
      </para>

      <para>
        <command>b10-loadzone</command> supports the following
        special directives (control entries):

        <variablelist>

          <varlistentry>
            <term>$INCLUDE</term>
            <listitem>
              <simpara>Loads an additional zone file. This may be recursive.
              </simpara>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>$ORIGIN</term>
            <listitem>
              <simpara>Defines the relative domain name.
              </simpara>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>$TTL</term>
            <listitem>
              <simpara>Defines the time-to-live value used for following
                records that don't include a TTL.
              </simpara>
            </listitem>
          </varlistentry>

        </variablelist>

      </para>

      <para>
        The <option>-o</option> argument may be used to define the
        default origin for loaded zone file records.
      </para>

      <note>
      <para>
        In the development prototype release, only the SQLite3 back
        end is used.
        By default, it stores the zone data in
        <filename>/usr/local/var/bind10-devel/zone.sqlite3</filename>
        unless the <option>-d</option> switch is used to set the
        database filename.
        Multiple zones are stored in a single SQLite3 zone database.
      </para>
      </note>

      <para>
        If you reload a zone already existing in the database,
        all records from that prior zone disappear and a whole new set
        appears.
      </para>

<!--TODO: permissions for xfrin or loadzone to create the file -->

    </section>

<!--
TODO
    <section>
      <title>Troubleshooting</title>
      <para>
      </para>
    </section>
-->

  </chapter>

  <chapter id="xfrin">
    <title>Incoming Zone Transfers</title>

    <para>
      Incoming zones are transferred using the <command>b10-xfrin</command>
      process which is started by <command>bind10</command>.
      When received, the zone is stored in the corresponding BIND 10
      data source, and its records can be served by
      <command>b10-auth</command>.
      In combination with <command>b10-zonemgr</command> (for
      automated SOA checks), this allows the BIND 10 server to
      provide <quote>secondary</quote> service.
    </para>

    <para>
      The <command>b10-xfrin</command> process supports both AXFR and
      IXFR.  Due to some implementation limitations of the current
      development release, however, it only tries AXFR by default,
      and care should be taken to enable IXFR.
    </para>
<!-- TODO: http://bind10.isc.org/ticket/1279 -->

    <note><simpara>
     In the current development release of BIND 10, incoming zone
     transfers are only available for SQLite3-based data sources,
     that is, they don't work for an in-memory data source.
    </simpara></note>

    <section>
      <title>Configuration for Incoming Zone Transfers</title>
      <para>
        In practice, you need to specify a list of secondary zones to
        enable incoming zone transfers for these zones (you can still
        trigger a zone transfer manually, without a prior configuration
        (see below)).
      </para>

      <para>
        For example, to enable zone transfers for a zone named "example.com"
        (whose master address is assumed to be 2001:db8::53 here),
        run the following at the <command>bindctl</command> prompt:

      <screen>&gt; <userinput>config add Xfrin/zones</userinput>
&gt; <userinput>config set Xfrin/zones[0]/name "<option>example.com</option>"</userinput>
&gt; <userinput>config set Xfrin/zones[0]/master_addr "<option>2001:db8::53</option>"</userinput>
&gt; <userinput>config commit</userinput></screen>

      (We assume there has been no zone configuration before).
      </para>
    </section>

    <section>
      <title>Enabling IXFR</title>
      <para>
        As noted above, <command>b10-xfrin</command> uses AXFR for
        zone transfers by default.  To enable IXFR for zone transfers
        for a particular zone, set the <userinput>use_ixfr</userinput>
        configuration parameter to <userinput>true</userinput>.
        In the above example of configuration sequence, you'll need
        to add the following before performing <userinput>commit</userinput>:
      <screen>&gt; <userinput>config set Xfrin/zones[0]/use_ixfr true</userinput></screen>
      </para>

<!-- TODO: http://bind10.isc.org/ticket/1279 -->
      <note><simpara>
      One reason why IXFR is disabled by default in the current
      release is because it does not support automatic fallback from IXFR to
      AXFR when it encounters a primary server that doesn't support
      outbound IXFR (and, not many existing implementations support
      it).  Another, related reason is that it does not use AXFR even
      if it has no knowledge about the zone (like at the very first
      time the secondary server is set up).  IXFR requires the
      "current version" of the zone, so obviously it doesn't work
      in this situation and AXFR is the only workable choice.
      The current release of <command>b10-xfrin</command> does not
      make this selection automatically.
      These features will be implemented in a near future
      version, at which point we will enable IXFR by default.
      </simpara></note>
    </section>

<!-- TODO:

how to tell bind10 you are a secondary?

when will it first attempt to check for new zone? (using REFRESH?)
what if zonemgr is not running?

what if a NOTIFY is sent?

-->

    <section id="zonemgr">
      <title>Secondary Manager</title>

      <para>
        The <command>b10-zonemgr</command> process is started by
        <command>bind10</command>.
        It keeps track of SOA refresh, retry, and expire timers
        and other details for BIND 10 to perform as a slave.
        When the <command>b10-auth</command> authoritative DNS server
        receives a NOTIFY message, <command>b10-zonemgr</command>
        may tell <command>b10-xfrin</command> to do a refresh
        to start an inbound zone transfer.
        The secondary manager resets its counters when a new zone is
        transferred in.
      </para>

      <note><simpara>
        Access control (such as allowing notifies) is not yet provided.
        The primary/secondary service is not yet complete.
      </simpara></note>

      <para>
        The following example shows using <command>bindctl</command>
        to configure the server to be a secondary for the example zone:

      <screen>&gt; <userinput>config add Zonemgr/secondary_zones</userinput>
&gt; <userinput>config set Zonemgr/secondary_zones[0]/name "<option>example.com</option>"</userinput>
&gt; <userinput>config set Zonemgr/secondary_zones[0]/class "<option>IN</option>"</userinput>
&gt; <userinput>config commit</userinput></screen>

<!-- TODO: remove the IN class example above when it is the default -->

      </para>

      <para>
        If the zone does not exist in the data source already
        (i.e. no SOA record for it), <command>b10-zonemgr</command>
        will automatically tell <command>b10-xfrin</command>
        to transfer the zone in.
      </para>

    </section>

    <section>
      <title>Trigger an Incoming Zone Transfer Manually</title>

      <para>
        To manually trigger a zone transfer to retrieve a remote zone,
        you may use the <command>bindctl</command> utility.
        For example, at the <command>bindctl</command> prompt run:

        <screen>&gt; <userinput>Xfrin retransfer zone_name="<option>foo.example.org</option>" master=<option>192.0.2.99</option></userinput></screen>
      </para>
    </section>

<!-- TODO: can that retransfer be used to identify a new zone? -->
<!-- TODO: what if doesn't exist at that master IP? -->

  </chapter>

  <chapter id="xfrout">
    <title>Outbound Zone Transfers</title>

    <para>
      The <command>b10-xfrout</command> process is started by
      <command>bind10</command>.
      When the <command>b10-auth</command> authoritative DNS server
      receives an AXFR or IXFR request, <command>b10-auth</command>
      internally forwards the request to <command>b10-xfrout</command>,
      which handles the rest of request processing.
      This is used to provide primary DNS service to share zones
      to secondary name servers.
      The <command>b10-xfrout</command> is also used to send
      NOTIFY messages to secondary servers.
    </para>

    <para>
      A global or per zone <option>transfer_acl</option> configuration
      can be used to control accessibility of the outbound zone
      transfer service.
      By default, <command>b10-xfrout</command> allows any clients to
      perform zone transfers for any zones:
    </para>

      <screen>&gt; <userinput>config show Xfrout/transfer_acl</userinput>
Xfrout/transfer_acl[0]	{"action": "ACCEPT"}	any	(default)</screen>

    <para>
      You can change this to, for example, rejecting all transfer
      requests by default while allowing requests for the transfer
      of zone "example.com" from 192.0.2.1 and 2001:db8::1 as follows:
    </para>

      <screen>&gt; <userinput>config set Xfrout/transfer_acl[0] {"action": "REJECT"}</userinput>
&gt; <userinput>config add Xfrout/zone_config</userinput>
&gt; <userinput>config set Xfrout/zone_config[0]/origin "example.com"</userinput>
&gt; <userinput>config set Xfrout/zone_config[0]/transfer_acl [{"action": "ACCEPT", "from": "192.0.2.1"},</userinput>
<userinput>                                                 {"action": "ACCEPT", "from": "2001:db8::1"}]</userinput>
&gt; <userinput>config commit</userinput></screen>

    <note><simpara>
        In the above example the lines
        for <option>transfer_acl</option> were divided for
        readability.  In the actual input it must be in a single line.
    </simpara></note>

    <para>
      If you want to require TSIG in access control, a separate TSIG
      "key ring" must be configured specifically
      for <command>b10-xfrout</command> as well as a system wide
      key ring, both containing a consistent set of keys.
      For example, to change the previous example to allowing requests
      from 192.0.2.1 signed by a TSIG with a key name of
      "key.example", you'll need to do this:
    </para>

    <screen>&gt; <userinput>config set tsig_keys/keys ["key.example:&lt;base64-key&gt;"]</userinput>
&gt; <userinput>config set Xfrout/tsig_keys/keys ["key.example:&lt;base64-key&gt;"]</userinput>
&gt; <userinput>config set Xfrout/zone_config[0]/transfer_acl [{"action": "ACCEPT", "from": "192.0.2.1", "key": "key.example"}]</userinput>
&gt; <userinput>config commit</userinput></screen>

    <para>
      The first line of configuration defines a system wide key ring.
      This is necessary because the <command>b10-auth</command> server
      also checks TSIGs and it uses the system wide configuration.
    </para>

    <note><simpara>
        In a future version, <command>b10-xfrout</command> will also
        use the system wide TSIG configuration.
        The way to specify zone specific configuration (ACLs, etc) is
        likely to be changed, too.
    </simpara></note>

<!--
TODO:
xfrout section:
auth servers checks for AXFR query
sends the XFR query to the xfrout module
uses /tmp/auth_xfrout_conn which is a socket
what is XfroutClient xfr_client??
/tmp/auth_xfrout_conn is not removed
-->

  </chapter>

  <chapter id="resolverserver">
    <title>Recursive Name Server</title>

    <para>
      The <command>b10-resolver</command> process is started by
      <command>bind10</command>.
<!-- TODO
      It provides a resolver so DNS clients can ask it to do recursion
      and it will return answers.
-->
    </para>

    <para>
      The main <command>bind10</command> process can be configured
      to select to run either the authoritative or resolver or both.
      By default, it starts the authoritative service.
<!-- TODO: later both -->

      You may change this using <command>bindctl</command>, for example:

      <screen>
&gt; <userinput>config remove Boss/components b10-xfrout</userinput>
&gt; <userinput>config remove Boss/components b10-xfrin</userinput>
&gt; <userinput>config remove Boss/components b10-auth</userinput>
&gt; <userinput>config add Boss/components b10-resolver</userinput>
&gt; <userinput>config set Boss/components/b10-resolver/special resolver</userinput>
&gt; <userinput>config set Boss/components/b10-resolver/kind needed</userinput>
&gt; <userinput>config set Boss/components/b10-resolver/priority 10</userinput>
&gt; <userinput>config commit</userinput>
</screen>

    </para>

    <para>
       The master <command>bind10</command> will stop and start
       the desired services.
    </para>

    <para>
      By default, the resolver listens on port 53 for 127.0.0.1 and ::1.
      The following example shows how it can be configured to
      listen on an additional address (and port):

      <screen>
&gt; <userinput>config add Resolver/listen_on</userinput>
&gt; <userinput>config set Resolver/listen_on[<replaceable>2</replaceable>]/address "192.168.1.1"</userinput>
&gt; <userinput>config set Resolver/listen_on[<replaceable>2</replaceable>]/port 53</userinput>
&gt; <userinput>config commit</userinput>
</screen>
    </para>

     <simpara>(Replace the <quote><replaceable>2</replaceable></quote>
       as needed; run <quote><userinput>config show
       Resolver/listen_on</userinput></quote> if needed.)</simpara>
<!-- TODO: this example should not include the port, ticket #1185 -->

    <section>
      <title>Access Control</title>

      <para>
        By default, the <command>b10-resolver</command> daemon only accepts
        DNS queries from the localhost (127.0.0.1 and ::1).
        The <option>Resolver/query_acl</option> configuration may
        be used to reject, drop, or allow specific IPs or networks.
        This configuration list is first match.
      </para>

      <para>
        The configuration's <option>action</option> item may be
        set to <quote>ACCEPT</quote> to allow the incoming query,
        <quote>REJECT</quote> to respond with a DNS REFUSED return
        code, or <quote>DROP</quote> to ignore the query without
        any response (such as a blackhole).  For more information,
        see the respective debugging messages:  <ulink
        url="bind10-messages.html#RESOLVER_QUERY_ACCEPTED">RESOLVER_QUERY_ACCEPTED</ulink>,
        <ulink
        url="bind10-messages.html#RESOLVER_QUERY_REJECTED">RESOLVER_QUERY_REJECTED</ulink>,
        and <ulink
url="bind10-messages.html#RESOLVER_QUERY_DROPPED">RESOLVER_QUERY_DROPPED</ulink>.
      </para>

      <para>
        The required configuration's <option>from</option> item is set
        to an IPv4 or IPv6 address, addresses with an network mask, or to
        the special lowercase keywords <quote>any6</quote> (for
        any IPv6 address) or <quote>any4</quote> (for any IPv4
        address).
      </para>

<!-- TODO:
/0 is for any address in that address family
does that need any address too?

TODO: tsig
-->

      <para>
        For example to allow the <replaceable>192.168.1.0/24</replaceable>
        network to use your recursive name server, at the
        <command>bindctl</command> prompt run:
      </para>

      <screen>
&gt; <userinput>config add Resolver/query_acl</userinput>
&gt; <userinput>config set Resolver/query_acl[<replaceable>2</replaceable>]/action "ACCEPT"</userinput>
&gt; <userinput>config set Resolver/query_acl[<replaceable>2</replaceable>]/from "<replaceable>192.168.1.0/24</replaceable>"</userinput>
&gt; <userinput>config commit</userinput>
</screen>

     <simpara>(Replace the <quote><replaceable>2</replaceable></quote>
       as needed; run <quote><userinput>config show
       Resolver/query_acl</userinput></quote> if needed.)</simpara>

<!-- TODO: check this -->
      <note><simpara>This prototype access control configuration
      syntax may be changed.</simpara></note>

    </section>

    <section>
      <title>Forwarding</title>

      <para>

        To enable forwarding, the upstream address and port must be
        configured to forward queries to, such as:

        <screen>
&gt; <userinput>config set Resolver/forward_addresses [{ "address": "<replaceable>192.168.1.1</replaceable>", "port": 53 }]</userinput>
&gt; <userinput>config commit</userinput>
</screen>

        (Replace <replaceable>192.168.1.1</replaceable> to point to your
        full resolver.)
      </para>

      <para>
        Normal iterative name service can be re-enabled by clearing the
        forwarding address(es); for example:

        <screen>
&gt; <userinput>config set Resolver/forward_addresses []</userinput>
&gt; <userinput>config commit</userinput>
</screen>
      </para>

    </section>

<!-- TODO: later try this

> config set Resolver/forward_addresses[0]/address "192.168.8.8"
> config set Resolver/forward_addresses[0]/port 53
then change those defaults with config set Resolver/forward_addresses[0]/address "1.2.3.4"
> config set Resolver/forward_addresses[0]/address "1.2.3.4"
-->

  </chapter>

  <chapter id="dhcp4">
    <title>DHCPv4 Server</title>
    <para>Dynamic Host Configuration Protocol for IPv4 (DHCP or
    DHCPv4) and Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
    are protocols that allow one node (server) to provision
    configuration parameters to many hosts and devices (clients). To
    ease deployment in larger networks, additional nodes (relays) may
    be deployed that facilitate communication between servers and
    clients. Even though principles of both DHCPv4 and DHCPv6 are
    somewhat similar, these are two radically different
    protocols. BIND10 offers server implementations for both DHCPv4
    and DHCPv6.</para>

    <note>
      <para>
        As of December 2011, both DHCPv4 and DHCPv6 components are
        skeleton servers. That means that while they are capable of
        performing DHCP configuration, they are not fully functional
        yet. In particular, both do not have functional lease
        databases. This means that they will assign the same, fixed,
        hardcoded addresses to any client that will ask. See <xref
        linkend="dhcp4-limit"/> and <xref linkend="dhcp6-limit"/> for
        detailed description.
      </para>
    </note>

    <section>
      <title>Server Usage</title>
      <para>BIND10 provides experimental DHCPv4 server component since
      December 2011. It is currently described as skeleton server and
      can be described as an early prototype that is not yet fully
      functional. It is mature enough to conduct first tests in lab
      environment, but it has significant limitations. See <xref
      linkend="dhcp4-limit"/> for details.
      </para>

      <para>
        DHCPv4 server is implemented as <command>b10-dhcp4</command>
        daemon. As it is configurable yet, it is fully autonomous,
        i.e. it does not interact with <command>b10-cfgmgr</command>.
        To start DHCPv4 server, simply input:

        <screen>
#<userinput>cd src/bin/dhcp4</userinput>
#<userinput>./b10-dhcp4</userinput>
</screen>

        Depending on your installation, <command>b10-dhcp4</command>
        binary may reside in src/bin/dhcp4 in your source code
        directory, in /usr/local/bin/b10-dhcp4 or other directory
        you specified during compilation.

        Afre start, server will detect available network interfaces
        and will attempt to open UDP sockets on all interfaces that
        are up, running, are not loopback and have IPv4 address
        assigned.

        Server will then listen to incoming traffic. Currently
        supported client messages are DISCOVER and REQUEST. Server
        will respond to them with OFFER and ACK, respectively.

        As DHCPv4 server opens privileged ports, it requires root
        access. Make sure you run this daemon as root.
      </para>
    </section>

    <section id="dhcp4-config">
      <title>Server Configuration</title>
      <para>
        DHCPv4 server does not have lease database implemented yet
        or any support for configuration, so every time the same set
        of configuration options (including the same fixed address)
        will be assigned every time.
      </para>
      <para>
        At this stage of development, the only way to alter server
        configuration is to tweak its source code. To do so, please edit
        src/bin/dhcp4/dhcp4_srv.cc file and modify following parameters:
        <screen>
const std::string HARDCODED_LEASE = "10.3.2.222"; // assigned lease
const std::string HARDCODED_NETMASK = "255.255.255.0";
const uint32_t    HARDCODED_LEASE_TIME = 60; // in seconds
const std::string HARDCODED_GATEWAY = "10.3.2.2";
const std::string HARDCODED_DNS_SERVER = "8.8.8.8";
const std::string HARDCODED_DOMAIN_NAME = "isc.example.org";
const std::string HARDCODED_SERVER_ID = "10.3.1.1";</screen>

        Lease database and configuration support is planned for 2012.
      </para>
    </section>

    <section id="dhcp4-limit">
      <title>DHCPv4 Server Limitations</title>
      <para>
        This are the current limitations of DHCPv4 server
        software. Most of them are reflection of the early stage of
        development.
      </para>
      <itemizedlist>
          <listitem>
            <simpara>During initial IPv4 node configuration, where server has to
        send packet to a node that does not have IPv4 address
        assigned yet, server requires certain tricks (or hacks) to
        transmit such packets. This is not implemented yet, therefore
        DHCPv4 server supports relayed traffic only.</simpara>
          </listitem>
          <listitem>
            <simpara>It provides a single, fixed, hardcoded lease to
            any client that asks.  There is no lease manager
            implemented. If two clients request addresses, they will
            both get the same fixed address.</simpara>
          </listitem>
          <listitem>
            <simpara>Server does not support any configuration
            mechanisms yet. The whole configuration is currently
            hardcoded. The only way to tweak configuration is to
            directly modify source code. See see <xref
            linkend="dhcp4-config"/> for details.</simpara>
          </listitem>
          <listitem>
            <simpara>Upon start, server will open sockets on all
            interfaces that are not loopback, are up and running and
            have IPv4 address.  Support for multiple interfaces is not
            coded in reception routines yet, so if you are running
            this code on a machine that has many interfaces and
            <command>b10-dhcp4</command> happens to listen on wrong
            interface, the easiest way to is to down other
            interfaces. This limitation will be fixed shortly.</simpara>
          </listitem>
          <listitem>
            <simpara>PRL (Parameter Request List) is currently ignored
            and server assigns DNS SERVER and DOMAIN NAME
            options.</simpara>
          </listitem>
          <listitem>
            <simpara><command>b10-dhcp4</command> does not support
            BOOTP. That is a design choice. This limitation is
            permanent. If have legacy nodes that can't use DHCP and
            require BOOTP support, please use latest version of ISC DHCP
            <ulink url="http://www.isc.org/software/dhcp"/>.</simpara>
          </listitem>
          <listitem>
            <simpara>Interface detection is currently working on Linux
            only. See <xref linkend="iface-detect"/> for details.</simpara>
          </listitem>
      </itemizedlist>

    </section>
  </chapter>

  <chapter id="dhcp6-srv">
    <title>DHCPv6 Server</title>
    <section id="dhcp6-limit">
      <title>DHCPv6 Server Limitations</title>
      <para>
        Relayed traffic is not supported.
      </para>
    </section>


  </chapter>

  <chapter id="libdhcp++">
    <title>libdhcp++ library</title>
    <para>libdhcp++ is a common library written in C++ that is
    handles many DHCP-related tasks, like DHCPv4 and DHCPv6 packets
    parsing, manipulation and assembly, option parsing, manipulation
    and assembly, network interface detection and socket operations.
    </para>

    <para>
    While this library is currently used by
    <command>b10-dhcp6</command> and <command>b10-dhcp4</command>
    only, it is designed to be portable, universal library useful
    for any kind of DHCP-related software.
    </para>

    <section id="iface-detect">
      <title>Interface detection</title>
      <para>Both DHCPv4 and DHCPv6 components share network
      interface detection routines. Interface detection is
      currently only supported on Linux systems.</para>

      <para>For non-linux systems, there is currently stub
      implementation provided. As DHCP servers need to know
      available addresses, there was a simple mechanism implemented
      to provide that information. User is expected to create
      interfaces.txt file. Format of this file is simple. It
      contains list of interfaces along with available address on
      each interface. This mechanism is temporary and is going to be
      removed as soon as interface detection becomes available on
      non-linux systems. Example of interfaces.txt file looks as follows:
      <screen>
# For DHCPv6, please specify link-local address (starts with fe80::)
# If in doubt, check output of 'ifconfig -a' command.
eth0 fe80::21e:8cff:fe9b:7349

# For DHCPv4, please use following format:
#eth0 192.0.2.5</screen>
      </para>
    </section>

  </chapter>

  <chapter id="statistics">
    <title>Statistics</title>

    <para>
      The <command>b10-stats</command> process is started by
      <command>bind10</command>.
      It periodically collects statistics data from various modules
      and aggregates it.
<!-- TODO -->
    </para>

    <para>

       This stats daemon provides commands to identify if it is
       running, show specified or all statistics data, show specified
       or all statistics data schema, and set specified statistics
       data.

       For example, using <command>bindctl</command>:

       <screen>
&gt; <userinput>Stats show</userinput>
{
    "Auth": {
        "queries.tcp": 1749,
        "queries.udp": 867868
    },
    "Boss": {
        "boot_time": "2011-01-20T16:59:03Z"
    },
    "Stats": {
        "boot_time": "2011-01-20T16:59:05Z",
        "last_update_time": "2011-01-20T17:04:05Z",
        "lname": "4d3869d9_a@jreed.example.net",
        "report_time": "2011-01-20T17:04:06Z",
        "timestamp": 1295543046.823504
    }
}
       </screen>
    </para>

  </chapter>

  <chapter id="logging">
    <title>Logging</title>

    <section>
      <title>Logging configuration</title>

      <para>

        The logging system in BIND 10 is configured through the
        Logging module. All BIND 10 modules will look at the
        configuration in Logging to see what should be logged and
        to where.

<!-- TODO: what is context of Logging module for readers of this guide? -->

      </para>

      <section>
        <title>Loggers</title>

        <para>

          Within BIND 10, a message is logged through a component
          called a "logger". Different parts of BIND 10 log messages
          through different loggers, and each logger can be configured
          independently of one another.

        </para>

        <para>

          In the Logging module, you can specify the configuration
          for zero or more loggers; any that are not specified will
          take appropriate default values..

        </para>

        <para>

          The three most important elements of a logger configuration
          are the <option>name</option> (the component that is
          generating the messages), the <option>severity</option>
          (what to log), and the <option>output_options</option>
          (where to log).

        </para>

        <section>
          <title>name (string)</title>

          <para>
          Each logger in the system has a name, the name being that
          of the component using it to log messages. For instance,
          if you want to configure logging for the resolver module,
          you add an entry for a logger named <quote>Resolver</quote>. This
          configuration will then be used by the loggers in the
          Resolver module, and all the libraries used by it.
              </para>

<!-- TODO: later we will have a way to know names of all modules

Right now you can only see what their names are if they are running
(a simple 'help' without anything else in bindctl for instance).

 -->

        <para>

          If you want to specify logging for one specific library
          within the module, you set the name to
          <replaceable>module.library</replaceable>.  For example, the
          logger used by the nameserver address store component
          has the full name of <quote>Resolver.nsas</quote>. If
          there is no entry in Logging for a particular library,
          it will use the configuration given for the module.

<!-- TODO: how to know these specific names?

We will either have to document them or tell the administrator to
specify module-wide logging and see what appears...

-->

        </para>

        <para>

<!-- TODO: severity has not been covered yet -->

          To illustrate this, suppose you want the cache library
          to log messages of severity DEBUG, and the rest of the
          resolver code to log messages of severity INFO. To achieve
          this you specify two loggers, one with the name
          <quote>Resolver</quote> and severity INFO, and one with
          the name <quote>Resolver.cache</quote> with severity
          DEBUG. As there are no entries for other libraries (e.g.
          the nsas), they will use the configuration for the module
          (<quote>Resolver</quote>), so giving the desired behavior.

        </para>

        <para>

          One special case is that of a module name of <quote>*</quote>
          (asterisks), which is interpreted as <emphasis>any</emphasis>
          module. You can set global logging options by using this,
          including setting the logging configuration for a library
          that is used by multiple modules (e.g. <quote>*.config</quote>
          specifies the configuration library code in whatever
          module is using it).

        </para>

        <para>

          If there are multiple logger specifications in the
          configuration that might match a particular logger, the
          specification with the more specific logger name takes
          precedence. For example, if there are entries for for
          both <quote>*</quote> and <quote>Resolver</quote>, the
          resolver module &mdash; and all libraries it uses &mdash;
          will log messages according to the configuration in the
          second entry (<quote>Resolver</quote>). All other modules
          will use the configuration of the first entry
          (<quote>*</quote>). If there was also a configuration
          entry for <quote>Resolver.cache</quote>, the cache library
          within the resolver would use that in preference to the
          entry for <quote>Resolver</quote>.

        </para>

        <para>

          One final note about the naming. When specifying the
          module name within a logger, use the name of the module
          as specified in <command>bindctl</command>, e.g.
          <quote>Resolver</quote> for the resolver module,
          <quote>Xfrout</quote> for the xfrout module, etc. When
          the message is logged, the message will include the name
          of the logger generating the message, but with the module
          name replaced by the name of the process implementing
          the module (so for example, a message generated by the
          <quote>Auth.cache</quote> logger will appear in the output
          with a logger name of <quote>b10-auth.cache</quote>).

        </para>

        </section>

        <section>
          <title>severity (string)</title>

        <para>

          This specifies the category of messages logged.
          Each message is logged with an associated severity which
          may be one of the following (in descending order of
          severity):
        </para>

        <itemizedlist>
          <listitem>
            <simpara> FATAL </simpara>
          </listitem>

          <listitem>
            <simpara> ERROR </simpara>
          </listitem>

          <listitem>
            <simpara> WARN </simpara>
          </listitem>

          <listitem>
            <simpara> INFO </simpara>
          </listitem>

          <listitem>
            <simpara> DEBUG </simpara>
          </listitem>
        </itemizedlist>

        <para>

          When the severity of a logger is set to one of these
          values, it will only log messages of that severity, and
          the severities above it. The severity may also be set to
          NONE, in which case all messages from that logger are
          inhibited.

<!-- TODO: worded wrong? If I set to INFO, why would it show DEBUG which is literally below in that list? -->

        </para>

        </section>

        <section>
          <title>output_options (list)</title>

        <para>

          Each logger can have zero or more
          <option>output_options</option>. These specify where log
          messages are sent to. These are explained in detail below.

        </para>

        <para>

          The other options for a logger are:

        </para>

        </section>

        <section>
          <title>debuglevel (integer)</title>

        <para>

          When a logger's severity is set to DEBUG, this value
          specifies what debug messages should be printed. It ranges
          from 0 (least verbose) to 99 (most verbose).
        </para>


<!-- TODO: complete this sentence:

          The general classification of debug message types is

TODO; there's a ticket to determine these levels, see #1074

 -->

        <para>

          If severity for the logger is not DEBUG, this value is ignored.

        </para>

        </section>

        <section>
          <title>additive (true or false)</title>

        <para>

          If this is true, the <option>output_options</option> from
          the parent will be used. For example, if there are two
          loggers configured; <quote>Resolver</quote> and
          <quote>Resolver.cache</quote>, and <option>additive</option>
          is true in the second, it will write the log messages
          not only to the destinations specified for
          <quote>Resolver.cache</quote>, but also to the destinations
          as specified in the <option>output_options</option> in
          the logger named <quote>Resolver</quote>.

<!-- TODO: check this -->

      </para>

      </section>

      </section>

      <section>
        <title>Output Options</title>

        <para>

          The main settings for an output option are the
          <option>destination</option> and a value called
          <option>output</option>, the meaning of which depends on
          the destination that is set.

        </para>

        <section>
          <title>destination (string)</title>

          <para>

            The destination is the type of output. It can be one of:

          </para>

          <itemizedlist>

            <listitem>
              <simpara> console </simpara>
          </listitem>

            <listitem>
              <simpara> file </simpara>
          </listitem>

            <listitem>
              <simpara> syslog </simpara>
            </listitem>

          </itemizedlist>

        </section>

        <section>
          <title>output (string)</title>

        <para>

          Depending on what is set as the output destination, this
          value is interpreted as follows:

        </para>

        <variablelist>

          <varlistentry>
            <term><option>destination</option> is <quote>console</quote></term>
            <listitem>
              <simpara>
                 The value of output must be one of <quote>stdout</quote>
                 (messages printed to standard output) or
                 <quote>stderr</quote> (messages printed to standard
                 error).
              </simpara>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term><option>destination</option> is <quote>file</quote></term>
            <listitem>
              <simpara>
                The value of output is interpreted as a file name;
                log messages will be appended to this file.
              </simpara>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term><option>destination</option> is <quote>syslog</quote></term>
            <listitem>
              <simpara>
                The value of output is interpreted as the
                <command>syslog</command> facility (e.g.
                <emphasis>local0</emphasis>) that should be used
                for log messages.
              </simpara>
            </listitem>
          </varlistentry>

        </variablelist>

        <para>

          The other options for <option>output_options</option> are:

        </para>

        <section>
          <title>flush (true of false)</title>

          <para>
            Flush buffers after each log message. Doing this will
            reduce performance but will ensure that if the program
            terminates abnormally, all messages up to the point of
            termination are output.
          </para>

        </section>

        <section>
          <title>maxsize (integer)</title>

          <para>
            Only relevant when destination is file, this is maximum
            file size of output files in bytes. When the maximum
            size is reached, the file is renamed and a new file opened.
            (For example, a ".1" is appended to the name &mdash;
            if a ".1" file exists, it is renamed ".2",
            etc.)
          </para>

          <para>
            If this is 0, no maximum file size is used.
          </para>

        </section>

        <section>
          <title>maxver (integer)</title>

          <para>
            Maximum number of old log files to keep around when
            rolling the output file. Only relevant when
            <option>destination</option> is <quote>file</quote>.
          </para>

        </section>

      </section>

      </section>

      <section>
        <title>Example session</title>

        <para>

          In this example we want to set the global logging to
          write to the file <filename>/var/log/my_bind10.log</filename>,
          at severity WARN. We want the authoritative server to
          log at DEBUG with debuglevel 40, to a different file
          (<filename>/tmp/debug_messages</filename>).

        </para>

        <para>

          Start <command>bindctl</command>.

        </para>

        <para>

           <screen>["login success "]
&gt; <userinput>config show Logging</userinput>
Logging/loggers	[]	list
</screen>

        </para>

        <para>

          By default, no specific loggers are configured, in which
          case the severity defaults to INFO and the output is
          written to stderr.

        </para>

        <para>

          Let's first add a default logger:

        </para>

<!-- TODO: adding the empty loggers makes no sense -->
        <para>

          <screen><userinput>&gt; config add Logging/loggers</userinput>
&gt; <userinput>config show Logging</userinput>
Logging/loggers/	list	(modified)
</screen>

        </para>

        <para>

          The loggers value line changed to indicate that it is no
          longer an empty list:

        </para>

        <para>

          <screen>&gt; <userinput>config show Logging/loggers</userinput>
Logging/loggers[0]/name	""	string	(default)
Logging/loggers[0]/severity	"INFO"	string	(default)
Logging/loggers[0]/debuglevel	0	integer	(default)
Logging/loggers[0]/additive	false	boolean	(default)
Logging/loggers[0]/output_options	[]	list	(default)
</screen>

        </para>

        <para>

          The name is mandatory, so we must set it. We will also
          change the severity as well. Let's start with the global
          logger.

        </para>

        <para>

          <screen>&gt; <userinput>config set Logging/loggers[0]/name *</userinput>
&gt; <userinput>config set Logging/loggers[0]/severity WARN</userinput>
&gt; <userinput>config show Logging/loggers</userinput>
Logging/loggers[0]/name	"*"	string	(modified)
Logging/loggers[0]/severity	"WARN"	string	(modified)
Logging/loggers[0]/debuglevel	0	integer	(default)
Logging/loggers[0]/additive	false	boolean	(default)
Logging/loggers[0]/output_options	[]	list	(default)
</screen>

        </para>

        <para>

          Of course, we need to specify where we want the log
          messages to go, so we add an entry for an output option.

        </para>

        <para>

          <screen>&gt; <userinput> config add Logging/loggers[0]/output_options</userinput>
&gt; <userinput> config show Logging/loggers[0]/output_options</userinput>
Logging/loggers[0]/output_options[0]/destination	"console"	string	(default)
Logging/loggers[0]/output_options[0]/output	"stdout"	string	(default)
Logging/loggers[0]/output_options[0]/flush	false	boolean	(default)
Logging/loggers[0]/output_options[0]/maxsize	0	integer	(default)
Logging/loggers[0]/output_options[0]/maxver	0	integer	(default)
</screen>


        </para>

        <para>

          These aren't the values we are looking for.

        </para>

        <para>

          <screen>&gt; <userinput> config set Logging/loggers[0]/output_options[0]/destination file</userinput>
&gt; <userinput> config set Logging/loggers[0]/output_options[0]/output /var/log/bind10.log</userinput>
&gt; <userinput> config set Logging/loggers[0]/output_options[0]/maxsize 30000</userinput>
&gt; <userinput> config set Logging/loggers[0]/output_options[0]/maxver 8</userinput>
</screen>

        </para>

        <para>

          Which would make the entire configuration for this logger
          look like:

        </para>

        <para>

          <screen>&gt; <userinput> config show all Logging/loggers</userinput>
Logging/loggers[0]/name	"*"	string	(modified)
Logging/loggers[0]/severity	"WARN"	string	(modified)
Logging/loggers[0]/debuglevel	0	integer	(default)
Logging/loggers[0]/additive	false	boolean	(default)
Logging/loggers[0]/output_options[0]/destination	"file"	string	(modified)
Logging/loggers[0]/output_options[0]/output	"/var/log/bind10.log"	string	(modified)
Logging/loggers[0]/output_options[0]/flush	false	boolean	(default)
Logging/loggers[0]/output_options[0]/maxsize	30000	integer	(modified)
Logging/loggers[0]/output_options[0]/maxver	8	integer	(modified)
</screen>

        </para>

        <para>

          That looks OK, so let's commit it before we add the
          configuration for the authoritative server's logger.

        </para>

        <para>

          <screen>&gt; <userinput> config commit</userinput></screen>

        </para>

        <para>

          Now that we have set it, and checked each value along
          the way, adding a second entry is quite similar.

        </para>

        <para>

          <screen>&gt; <userinput> config add Logging/loggers</userinput>
&gt; <userinput> config set Logging/loggers[1]/name Auth</userinput>
&gt; <userinput> config set Logging/loggers[1]/severity DEBUG</userinput>
&gt; <userinput> config set Logging/loggers[1]/debuglevel 40</userinput>
&gt; <userinput> config add Logging/loggers[1]/output_options</userinput>
&gt; <userinput> config set Logging/loggers[1]/output_options[0]/destination file</userinput>
&gt; <userinput> config set Logging/loggers[1]/output_options[0]/output /tmp/auth_debug.log</userinput>
&gt; <userinput> config commit</userinput>
</screen>

        </para>

        <para>

          And that's it. Once we have found whatever it was we
          needed the debug messages for, we can simply remove the
          second logger to let the authoritative server use the
          same settings as the rest.

        </para>

        <para>

          <screen>&gt; <userinput> config remove Logging/loggers[1]</userinput>
&gt; <userinput> config commit</userinput>
</screen>

        </para>

        <para>

          And every module will now be using the values from the
          logger named <quote>*</quote>.

        </para>

      </section>

    </section>

    <section>
      <title>Logging Message Format</title>

      <para>
          Each message written by BIND 10 to the configured logging
          destinations comprises a number of components that identify
          the origin of the message and, if the message indicates
          a problem, information about the problem that may be
          useful in fixing it.
      </para>

      <para>
          Consider the message below logged to a file:
          <screen>2011-06-15 13:48:22.034 ERROR [b10-resolver.asiolink]
    ASIODNS_OPENSOCK error 111 opening TCP socket to 127.0.0.1(53)</screen>
      </para>

      <para>
        Note: the layout of messages written to the system logging
        file (syslog) may be slightly different.  This message has
        been split across two lines here for display reasons; in the
        logging file, it will appear on one line.)
      </para>

      <para>
        The log message comprises a number of components:

          <variablelist>
          <varlistentry>
          <term>2011-06-15 13:48:22.034</term>
<!-- TODO: timestamp repeated even if using syslog? -->
          <listitem><para>
              The date and time at which the message was generated.
          </para></listitem>
          </varlistentry>

          <varlistentry>
          <term>ERROR</term>
          <listitem><para>
              The severity of the message.
          </para></listitem>
          </varlistentry>

          <varlistentry>
          <term>[b10-resolver.asiolink]</term>
          <listitem><para>
            The source of the message.  This comprises two components:
            the BIND 10 process generating the message (in this
            case, <command>b10-resolver</command>) and the module
            within the program from which the message originated
            (which in the example is the asynchronous I/O link
            module, asiolink).
          </para></listitem>
          </varlistentry>

          <varlistentry>
          <term>ASIODNS_OPENSOCK</term>
          <listitem><para>
            The message identification.  Every message in BIND 10
            has a unique identification, which can be used as an
            index into the <ulink
            url="bind10-messages.html"><citetitle>BIND 10 Messages
            Manual</citetitle></ulink> (<ulink
            url="http://bind10.isc.org/docs/bind10-messages.html"
            />) from which more information can be obtained.
          </para></listitem>
          </varlistentry>

          <varlistentry>
          <term>error 111 opening TCP socket to 127.0.0.1(53)</term>
          <listitem><para>
              A brief description of the cause of the problem.
              Within this text, information relating to the condition
              that caused the message to be logged will be included.
              In this example, error number 111 (an operating
              system-specific error number) was encountered when
              trying to open a TCP connection to port 53 on the
              local system (address 127.0.0.1).  The next step
              would be to find out the reason for the failure by
              consulting your system's documentation to identify
              what error number 111 means.
          </para></listitem>
          </varlistentry>
          </variablelist>
      </para>

    </section>

  </chapter>

<!-- TODO: how to help: run unit tests, join lists, review trac tickets -->

  <!-- <index>    <title>Index</title> </index> -->

</book>

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