<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="pam_wheel">

  <refmeta>
    <refentrytitle>pam_wheel</refentrytitle>
    <manvolnum>8</manvolnum>
    <refmiscinfo class="source">Linux-PAM</refmiscinfo>
    <refmiscinfo class="manual">Linux-PAM Manual</refmiscinfo>
  </refmeta>

  <refnamediv xml:id="pam_wheel-name">
    <refname>pam_wheel</refname>
    <refpurpose>Only permit root access to members of group wheel</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis xml:id="pam_wheel-cmdsynopsis" sepchar=" ">
      <command>pam_wheel.so</command>
      <arg choice="opt" rep="norepeat">
	debug
      </arg>
      <arg choice="opt" rep="norepeat">
        deny
      </arg>
      <arg choice="opt" rep="norepeat">
	group=<replaceable>name</replaceable>
      </arg>
      <arg choice="opt" rep="norepeat">
	root_only
      </arg>
      <arg choice="opt" rep="norepeat">
	trust
      </arg>
      <arg choice="opt" rep="norepeat">
	use_uid
      </arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1 xml:id="pam_wheel-description">
    <title>DESCRIPTION</title>
    <para>
      The pam_wheel PAM module is used to enforce the so-called
      <emphasis>wheel</emphasis> group. By default it permits
      access to the target user if the applicant user is a member of the
      <emphasis>wheel</emphasis> group. If no group with this name exist,
      the module is using the group with the group-ID
      <emphasis remap="B">0</emphasis>.
    </para>
  </refsect1>

  <refsect1 xml:id="pam_wheel-options">
    <title>OPTIONS</title>
    <variablelist>
      <varlistentry>
        <term>
          debug
        </term>
        <listitem>
          <para>
            Print debug information.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          deny
        </term>
        <listitem>
          <para>
            Reverse the sense of the auth operation: if the user
            is trying to get UID 0 access and is a member of the
            wheel group (or the group of the <option>group</option> option),
            deny access. Conversely, if the user is not in the group, return
            PAM_IGNORE (unless <option>trust</option> was also specified,
            in which case we return PAM_SUCCESS).
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          group=name
        </term>
        <listitem>
          <para>
            Instead of checking the wheel or GID 0 groups, use
            the <option><replaceable>name</replaceable></option> group
            to perform the authentication.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          root_only
        </term>
        <listitem>
          <para>
            The check for wheel membership is done only when the target user
            UID is 0.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          trust
        </term>
        <listitem>
          <para>
            The pam_wheel module will return PAM_SUCCESS instead
            of PAM_IGNORE if the user is a member of the wheel group
            (thus with a little play stacking the modules the wheel
            members may be able to su to root without being prompted
            for a passwd).
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          use_uid
        </term>
        <listitem>
          <para>
            The check will be done against the real uid of the calling process,
            instead of trying to obtain the user from the login session
            associated with the terminal in use.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 xml:id="pam_wheel-types">
    <title>MODULE TYPES PROVIDED</title>
    <para>
      The <emphasis remap="B">auth</emphasis> and
      <emphasis remap="B">account</emphasis> module types are provided.
    </para>
  </refsect1>

  <refsect1 xml:id="pam_wheel-return_values">
    <title>RETURN VALUES</title>
    <variablelist>
      <varlistentry>
        <term>PAM_AUTH_ERR</term>
        <listitem>
           <para>
             Authentication failure.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_BUF_ERR</term>
        <listitem>
           <para>
             Memory buffer error.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_IGNORE</term>
        <listitem>
          <para>
            The return value should be ignored by PAM dispatch.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_PERM_DENY</term>
        <listitem>
          <para>
            Permission denied.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_SERVICE_ERR</term>
        <listitem>
          <para>
	    Cannot determine the user name.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>PAM_SUCCESS</term>
        <listitem>
          <para>
            Success.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>PAM_USER_UNKNOWN</term>
        <listitem>
          <para>
            User not known.
          </para>
        </listitem>
      </varlistentry>

    </variablelist>
  </refsect1>

  <refsect1 xml:id="pam_wheel-examples">
    <title>EXAMPLES</title>
    <para>
      The root account gains access by default (rootok), only wheel
      members can become root (wheel) but Unix authenticate non-root
      applicants.
      <programlisting>
su      auth     sufficient     pam_rootok.so
su      auth     required       pam_wheel.so
su      auth     required       pam_unix.so
      </programlisting>
    </para>
  </refsect1>

  <refsect1 xml:id="pam_wheel-see_also">
    <title>SEE ALSO</title>
    <para>
      <citerefentry>
	<refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>
    </para>
  </refsect1>

  <refsect1 xml:id="pam_wheel-author">
    <title>AUTHOR</title>
      <para>
        pam_wheel was written by Cristian Gafton &lt;gafton@redhat.com&gt;.
      </para>
  </refsect1>

</refentry>