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  <chapter id="intro">
    <title>Introduction</title>
    <para>
      Kea is the next generation of DHCP software developed by ISC.
      It supports both DHCPv4 and DHCPv6 protocols along with their
      extensions, e.g. prefix delegation and dynamic updates to DNS.
    </para>

    <para>
      Kea was initially developed as a part of the BIND 10 framework.
      In early 2014, ISC made the decision to discontinue active
      development of BIND 10 and continue development of Kea as
      standalone DHCP software.
    </para>

    <para>
      This guide covers Kea version &__VERSION__;.
    </para>

    <section>
      <title>Supported Platforms</title>
      <para>
        Kea is officially supported on RedHat Enterprise Linux,
	CentOS, Fedora and FreeBSD systems. It is also likely to work on many
	other platforms: builds have been tested on (in no particular order)
        Debian GNU/Linux 6 and unstable, Ubuntu 9.10, NetBSD 5,
        Solaris 10 and 11, FreeBSD 7 and 8, CentOS Linux 5.3,
        MacOS 10.6 and 10.7, and OpenBSD 5.1. Non supported systems
	(especially non-Linux) are likely to have issues with directly
	connected DHCPv4 clients.
      </para>
      <para>There are currently no plans to port Kea to Windows platforms.</para>
    </section>

    <section id="required-software">
      <title>Required Software at Run-time</title>

      <para>
        Running Kea uses various extra software which may
        not be provided in the default installation of some operating systems,
        nor in the standard package collections. You may
        need to install this required software separately.
        (For the build requirements, also see
        <xref linkend="build-requirements"/>.)
      </para>

      <itemizedlist>

        <listitem>
            <simpara>
        Kea supports two crypto libraries: Botan and OpenSSL. Only one of them
        is required to be installed during compilation. Kea uses the Botan
        crypto library for C++ (<ulink url="http://botan.randombit.net/"/>),
        version 1.8 or later. As an alternative to Botan, Kea can use the
        OpenSSL crypto library (<ulink url="http://www.openssl.org/"/>).
        It requires a version with SHA-2 support.
            </simpara>
        </listitem>

        <listitem>
            <simpara>
        Kea uses the log4cplus C++ logging library
        (<ulink url="http://log4cplus.sourceforge.net/"/>).
        It requires at least log4cplus version 1.0.3.
            </simpara>
        </listitem>

        <listitem>
            <simpara>
	In order to store lease information in a MySQL database, Kea requires MySQL
    headers and libraries.  This is an optional dependency in that Kea can be
    built without MySQL support.
            </simpara>
        </listitem>

        <listitem>
            <simpara>
	In order to store lease information in a PostgreSQL database, Kea requires PostgreSQL
    headers and libraries.  This is an optional dependency in that Kea can be
    built without PostgreSQL support.
            </simpara>
        </listitem>
      </itemizedlist>
    </section>

    <section id="kea_software">
      <title>Kea Software</title>
      <para>
        Kea is modular.  Part of this modularity is
        accomplished using multiple cooperating processes which, together,
        provide the server functionality.
        The following software is included with Kea:
      </para>

      <para>

        <itemizedlist>

          <listitem>
            <simpara>
              <command>keactrl</command> &mdash;
              Tool to start, stop, reconfigure, and report status
              for the Kea servers.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>kea-dhcp4</command> &mdash;
              DHCPv4 server process.
              This process responds to DHCPv4 queries from clients.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>kea-dhcp6</command> &mdash;
              DHCPv6 server process.
              This process responds to DHCPv6 queries from clients.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>kea-dhcp-ddns</command> &mdash;
              DHCP-DDNS process.
              This process acts as an intermediary between the DHCP servers
              and DNS server. It receives name update requests from the DHCP
              servers and sends DNS Update messages to the DNS servers.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>kea-admin</command> &mdash;
              A tool useful for database backend maintenance (creating new
              database, checking versions, upgrading etc.)
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>kea-lfc</command> &mdash;
              This process removes redundant information from the files used
              to provide persistent storage for the memfile data base backend.
              The service is written to run as a stand alone process.  While it
              can be started externally it should be started by the Kea DHCP
              servers.
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              <command>perfdhcp</command> &mdash;
              DHCP benchmarking tool which simulates multiple clients to
              test both DHCPv4 and DHCPv6 servers performance.
            </simpara>
          </listitem>

        </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>

    <para>
      Kea also provides C++ libraries and programmer interfaces for
      DHCP.  These include detailed developer documentation and
      code examples.
<!-- TODO point to this -->
    </para>

  </chapter>
