impala/docs/topics/impala_ldap.xml

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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="ldap">

  <title>Enabling LDAP Authentication for Impala</title>
  <prolog>
    <metadata>
      <data name="Category" value="Security"/>
      <data name="Category" value="LDAP"/>
      <data name="Category" value="Authentication"/>
      <data name="Category" value="Impala"/>
      <data name="Category" value="Configuring"/>
      <data name="Category" value="Starting and Stopping"/>
      <data name="Category" value="Administrators"/>
    </metadata>
  </prolog>

  <conbody>

<!-- Similar discussion under 'Authentication' parent topic. Maybe do some conref'ing or linking upward. -->

    <p> Authentication is the process of allowing only specified named users to
      access the server (in this case, the Impala server). This feature is
      crucial for any production deployment, to prevent misuse, tampering, or
      excessive load on the server. Impala uses LDAP for authentication,
      verifying the credentials of each user who connects through
        <cmdname>impala-shell</cmdname>, Hue, a Business Intelligence tool, JDBC
      or ODBC application, and so on. </p>

    <note conref="../shared/impala_common.xml#common/authentication_vs_authorization"/>

    <p outputclass="toc inpage"/>

    <p>
      An alternative form of authentication you can use is Kerberos, described in
      <xref href="impala_kerberos.xml#kerberos"/>.
    </p>
  </conbody>

  <concept id="ldap_prereqs">

    <title>Requirements for Using Impala with LDAP</title>
  <prolog>
    <metadata>
      <data name="Category" value="Requirements"/>
      <data name="Category" value="Planning"/>
    </metadata>
  </prolog>

    <conbody>

      <p rev="1.4.0">
        Authentication against LDAP servers is available in Impala 1.2.2 and higher. Impala 1.4.0 adds support for
        secure LDAP authentication through SSL and TLS.
      </p>

      <p>
        The Impala LDAP support lets you use Impala with systems such as Active Directory that use LDAP behind the
        scenes.
      </p>
    </conbody>
  </concept>

  <concept id="ldap_client_server">

    <title>Client-Server Considerations for LDAP</title>

    <conbody>

      <p>
        Only client-&gt;Impala connections can be authenticated by LDAP.
      </p>

      <p> You must use the Kerberos authentication mechanism for connections
        between internal Impala components, such as between the
          <cmdname>impalad</cmdname>, <cmdname>statestored</cmdname>, and
          <cmdname>catalogd</cmdname> daemons. See <xref
          href="impala_kerberos.xml#kerberos" /> on how to set up Kerberos for
        Impala. </p>
    </conbody>
  </concept>

  <concept id="ldap_config">

    <title>Server-Side LDAP Setup</title>

    <conbody>

      <p>
        These requirements apply on the server side when configuring and starting Impala:
      </p>

      <p>
        To enable LDAP authentication, set the following startup options for <cmdname>impalad</cmdname>:
      </p>

      <ul>
        <li>
          <codeph>--enable_ldap_auth</codeph> enables LDAP-based authentication between the client and Impala.
        </li>

        <li rev="1.4.0">
          <codeph>--ldap_uri</codeph> sets the URI of the LDAP server to use. Typically, the URI is prefixed with
          <codeph>ldap://</codeph>. In Impala 1.4.0 and higher, you can specify secure SSL-based LDAP transport by
          using the prefix <codeph>ldaps://</codeph>. The URI can optionally specify the port, for example:
          <codeph>ldap://ldap_server.cloudera.com:389</codeph> or
          <codeph>ldaps://ldap_server.cloudera.com:636</codeph>. (389 and 636 are the default ports for non-SSL and
          SSL LDAP connections, respectively.)
        </li>

<!-- Some amount of this bullet could be conref'ed. Similar but not identical bullet occurs later under TLS. -->

        <li rev="1.4.0">
          For <codeph>ldaps://</codeph> connections secured by SSL,
          <codeph>--ldap_ca_certificate="<varname>/path/to/certificate/pem</varname>"</codeph> specifies the
          location of the certificate in standard <codeph>.PEM</codeph> format. Store this certificate on the local
          filesystem, in a location that only the <codeph>impala</codeph> user and other trusted users can read.
        </li>

<!-- Per Henry: not for public consumption.
<li>
  If you need to provide a custom SASL configuration,
  set <codeph>- -ldap_manual_config</codeph> to bypass all the automatic configuration.
</li>
-->
      </ul>
    </conbody>
  </concept>

  <concept id="ldap_bind_strings">

    <title>Support for Custom Bind Strings</title>

    <conbody>

      <p>
        When Impala connects to LDAP it issues a bind call to the LDAP server to authenticate as the connected
        user. Impala clients, including the Impala shell, provide the short name of the user to Impala. This is
        necessary so that Impala can use Sentry for role-based access, which uses short names.
      </p>

      <p>
        However, LDAP servers often require more complex, structured usernames for authentication. Impala supports
        three ways of transforming the short name (for example, <codeph>'henry'</codeph>) to a more complicated
        string. If necessary, specify one of the following configuration options when starting the
        <cmdname>impalad</cmdname> daemon on each DataNode:
      </p>

      <ul>
        <li>
          <codeph>--ldap_domain</codeph>: Replaces the username with a string
          <codeph><varname>username</varname>@<varname>ldap_domain</varname></codeph>.
        </li>

        <li>
          <codeph>--ldap_baseDN</codeph>: Replaces the username with a <q>distinguished name</q> (DN) of the form:
          <codeph>uid=<varname>userid</varname>,ldap_baseDN</codeph>. (This is equivalent to a Hive option).
        </li>

        <li>
          <codeph>--ldap_bind_pattern</codeph>: This is the most general option, and replaces the username with the
          string <varname>ldap_bind_pattern</varname> where all instances of the string <codeph>#UID</codeph> are
          replaced with <varname>userid</varname>. For example, an <codeph>ldap_bind_pattern</codeph> of
          <codeph>"user=#UID,OU=foo,CN=bar"</codeph> with a username of <codeph>henry</codeph> will construct a
          bind name of <codeph>"user=henry,OU=foo,CN=bar"</codeph>.
        </li>
      </ul>

      <p rev="CDH-26854">
        For clusters not managed by Cloudera Manager,
        specify the option on the <cmdname>impalad</cmdname> command line.
      </p>

      <p audience="hidden">
        For clusters managed by Cloudera Manager 5.4.0 and higher,
        search for the configuration field names <codeph>ldap_domain</codeph>,
        <codeph>ldap_basedn</codeph>, or <codeph>ldap_bind_pattern</codeph>,
        fill in and save the appropriate field values, and restart the Impala service.
        Prior to Cloudera Manager 5.4.0, these values were filled in using the
        <uicontrol>Impala Daemon Command Line Argument Advanced Configuration Snippet (Safety Valve)</uicontrol>
        field.
      </p>

      <p>
        These options are mutually exclusive; Impala does not start if more than one of these options is specified.
      </p>
    </conbody>
  </concept>

  <concept id="ldap_security">

    <title>Secure LDAP Connections</title>

    <conbody>

      <p>
        To avoid sending credentials over the wire in cleartext, you must configure a secure connection between
        both the client and Impala, and between Impala and the LDAP server. The secure connection could use SSL or
        TLS.
      </p>

      <p>
        <b>Secure LDAP connections through SSL:</b>
      </p>

      <p>
        For SSL-enabled LDAP connections, specify a prefix of <codeph>ldaps://</codeph> instead of
        <codeph>ldap://</codeph>. Also, the default port for SSL-enabled LDAP connections is 636 instead of 389.
      </p>

      <p rev="1.4.0">
        <b>Secure LDAP connections through TLS:</b>
      </p>

      <p>
        <xref href="http://en.wikipedia.org/wiki/Transport_Layer_Security" scope="external" format="html">TLS</xref>,
        the successor to the SSL protocol, is supported by most modern LDAP servers. Unlike SSL connections, TLS
        connections can be made on the same server port as non-TLS connections. To secure all connections using
        TLS, specify the following flags as startup options to the <cmdname>impalad</cmdname> daemon:
      </p>

      <ul>
        <li>
          <codeph>--ldap_tls</codeph> tells Impala to start a TLS connection to the LDAP server, and to fail
          authentication if it cannot be done.
        </li>

        <li rev="1.4.0">
          <codeph>--ldap_ca_certificate="<varname>/path/to/certificate/pem</varname>"</codeph> specifies the
          location of the certificate in standard <codeph>.PEM</codeph> format. Store this certificate on the local
          filesystem, in a location that only the <codeph>impala</codeph> user and other trusted users can read.
        </li>
      </ul>
    </conbody>
  </concept>

  <concept id="ldap_impala_shell">

    <title>LDAP Authentication for impala-shell Interpreter</title>

    <conbody>

      <p>
        To connect to Impala using LDAP authentication, you specify command-line options to the
        <cmdname>impala-shell</cmdname> command interpreter and enter the password when prompted:
      </p>

      <ul>
        <li>
          <codeph>-l</codeph> enables LDAP authentication.
        </li>

        <li>
          <codeph>-u</codeph> sets the user. Per Active Directory, the user is the short username, not the full
          LDAP distinguished name. If your LDAP settings include a search base, use the
          <codeph>--ldap_bind_pattern</codeph> on the <cmdname>impalad</cmdname> daemon to translate the short user
          name from <cmdname>impala-shell</cmdname> automatically to the fully qualified name.
<!--
include that as part of the
username, for example <codeph>username@example.com</codeph>.
-->
        </li>

        <li>
          <cmdname>impala-shell</cmdname> automatically prompts for the password.
        </li>
      </ul>

      <p>
        For the full list of available <cmdname>impala-shell</cmdname> options, see
        <xref href="impala_shell_options.xml#shell_options"/>.
      </p>

      <p>
        <b>LDAP authentication for JDBC applications:</b> See <xref href="impala_jdbc.xml#impala_jdbc"/> for the
        format to use with the JDBC connection string for servers using LDAP authentication.
      </p>
    </conbody>
  </concept>
  <concept id="ldap_impala_hue">
    <title>Enabling LDAP for Impala in Hue</title>
    <prolog>
      <metadata>
        <data name="Category" value="Hue"/>
      </metadata>
    </prolog>
    <conbody>
      <section id="ldap_impala_hue_cm" audience="hidden">
        <title>Enabling LDAP for Impala in Hue Using Cloudera Manager</title>
        <p>
          <ol>
            <li>Go to the Hue service.</li>
            <li>Click the Configuration tab.</li>
            <li>Select <menucascade><uicontrol>Scope</uicontrol><uicontrol>Hue
                  Server</uicontrol></menucascade>.</li>
            <li>Select
              <menucascade><uicontrol>Category</uicontrol><uicontrol>Advanced</uicontrol></menucascade>.</li>
            <li>Add the following properties to the <b>Hue Server Advanced
                Configuration Snippet (Safety Valve) for
                hue_safety_valve_server.ini</b>
              property.<codeblock>[impala]
auth_username=&lt;LDAP username of Hue user to be authenticated>
auth_password=&lt;LDAP password of Hue user to be authenticated></codeblock></li>
            <li>Click <b>Save Changes</b>.</li>
          </ol>
        </p>
      </section>
      <section id="ldap_impala_hue_cmdline">
        <title>Enabling LDAP for Impala in Hue Using the Command Line</title>
        <p>LDAP authentication for the Impala app in Hue can be enabled by
          setting the following properties under the <codeph>[impala]</codeph>
          section in <codeph>hue.ini</codeph>. <table id="ldap_impala_hue_configs">
            <tgroup cols="2">
              <colspec colname="1" colwidth="1*" />
              <colspec colname="2" colwidth="2*" />
              <tbody>
                <row>
                  <entry><codeph>auth_username</codeph></entry>
                  <entry>LDAP username of Hue user to be authenticated.</entry>
                </row>
                <row>
                  <entry><codeph>auth_password</codeph></entry>
                  <entry>
                    <p>LDAP password of Hue user to be authenticated.</p>
                  </entry>
                </row>
              </tbody>
            </tgroup>
          </table>These login details are only used by Impala to authenticate to
          LDAP. The Impala service trusts Hue to have already validated the user
          being impersonated, rather than simply passing on the credentials.</p>
      </section>
    </conbody>
  </concept>

  <concept id="ldap_delegation">
    <title>Enabling Impala Delegation for LDAP Users</title>
    <conbody>
      <p>
        See <xref href="impala_delegation.xml#delegation"/> for details about the delegation feature
        that lets certain users submit queries using the credentials of other users.
      </p>
    </conbody>
  </concept>

  <concept id="ldap_restrictions">

    <title>LDAP Restrictions for Impala</title>

    <conbody>

      <p>
        The LDAP support is preliminary. It currently has only been tested against Active Directory.
      </p>
    </conbody>
  </concept>
</concept>