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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>6.9. pam_filter - filter module</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot"><link rel="home" href="Linux-PAM_SAG.html" title="The Linux-PAM System Administrators' Guide"><link rel="up" href="sag-module-reference.html" title="Chapter 6. A reference guide for available modules"><link rel="prev" href="sag-pam_faildelay.html" title="6.8. pam_faildelay - change the delay on failure per-application"><link rel="next" href="sag-pam_ftp.html" title="6.10. pam_ftp - module for anonymous access"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">6.9. pam_filter - filter module</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="sag-pam_faildelay.html">Prev</a> </td><th width="60%" align="center">Chapter 6. A reference guide for available modules</th><td width="20%" align="right"> <a accesskey="n" href="sag-pam_ftp.html">Next</a></td></tr></table><hr></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sag-pam_filter"></a>6.9. pam_filter - filter module</h2></div></div></div><div class="cmdsynopsis"><p><code class="command">pam_filter.so</code>  [
	debug
      ] [
        new_term
      ] [
        non_term
      ]  
        run1|run2
         
        <em class="replaceable"><code>filter</code></em>
        [
        <em class="replaceable"><code>...</code></em>
      ]</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_filter-description"></a>6.9.1. DESCRIPTION</h3></div></div></div><p>
      This module is intended to be a platform for providing access to all
      of the input/output that passes between the user and the application.
      It is only suitable for tty-based and (stdin/stdout) applications.
    </p><p>
      To function this module requires <span class="emphasis"><em>filters</em></span> to be
      installed on the system.
      The single filter provided with the module simply transposes upper and
      lower case letters in the input and output streams. (This can be very
      annoying and is not kind to termcap based editors).
    </p><p>
      Each component of the module has the potential to invoke the
      desired filter. The filter is always
      <span class="citerefentry"><span class="refentrytitle">execv</span>(2)</span> with the privilege of the calling application
      and <span class="emphasis"><em>not</em></span> that of the user. For this reason it
      cannot usually be killed by the user without closing their session.
    </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_filter-options"></a>6.9.2. OPTIONS</h3></div></div></div><p>
      </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">
            <code class="option">debug</code>
          </span></dt><dd><p>
	      Print debug information.
            </p></dd><dt><span class="term">
            <code class="option">new_term</code>
          </span></dt><dd><p>
              The default action of the filter is to set the
              <span class="emphasis"><em>PAM_TTY</em></span> item to indicate the
              terminal that the user is using to connect to the
              application. This argument indicates that the filter
              should set <span class="emphasis"><em>PAM_TTY</em></span> to the filtered
              pseudo-terminal.
            </p></dd><dt><span class="term">
            <code class="option">non_term</code>
          </span></dt><dd><p>
              don't try to set the <span class="emphasis"><em>PAM_TTY</em></span> item.
            </p></dd><dt><span class="term">
            <code class="option">runX</code>
          </span></dt><dd><p>
              In order that the module can invoke a filter it should
              know when to invoke it. This argument is required to tell
              the filter when to do this.
            </p><p>
              Permitted values for <span class="emphasis"><em>X</em></span> are
              <span class="emphasis"><em>1</em></span> and <span class="emphasis"><em>2</em></span>. These
              indicate the precise time that the filter is to be run.
              To understand this concept it will be useful to have read
              the <span class="citerefentry"><span class="refentrytitle">pam</span>(3)</span> manual page.
              Basically, for each management group there are up to two ways
              of calling the module's functions.
              In the case of the <span class="emphasis"><em>authentication</em></span> and
              <span class="emphasis"><em>session</em></span> components there are actually
              two separate functions. For the case of authentication, these
              functions are
              <span class="citerefentry"><span class="refentrytitle">pam_authenticate</span>(3)</span> and
              <span class="citerefentry"><span class="refentrytitle">pam_setcred</span>(3)</span>, here <code class="option">run1</code> means run the
              filter from the <code class="function">pam_authenticate</code> function
              and <code class="option">run2</code> means run the filter from
              <code class="function">pam_setcred</code>. In the case of the
              session modules, <span class="emphasis"><em>run1</em></span> implies
              that the filter is invoked at the
              <span class="citerefentry"><span class="refentrytitle">pam_open_session</span>(3)</span> stage, and <span class="emphasis"><em>run2</em></span> for
              <span class="citerefentry"><span class="refentrytitle">pam_close_session</span>(3)</span>.
            </p><p>
              For the case of the account component. Either
              <span class="emphasis"><em>run1</em></span> or <span class="emphasis"><em>run2</em></span>
              may be used.
            </p><p>
              For the case of the password component, <span class="emphasis"><em>run1</em></span>
              is used to indicate that the filter is run on the first
              occasion of
              <span class="citerefentry"><span class="refentrytitle">pam_chauthtok</span>(3)</span> (the <span class="emphasis"><em>PAM_PRELIM_CHECK</em></span>
              phase) and <span class="emphasis"><em>run2</em></span> is used to indicate
              that the filter is run on the second occasion (the
              <span class="emphasis"><em>PAM_UPDATE_AUTHTOK</em></span> phase).

            </p></dd><dt><span class="term">
            <code class="option">filter</code>
          </span></dt><dd><p>
              The full pathname of the filter to be run and any command line
              arguments that the filter might expect.
            </p></dd></dl></div><p>

    </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_filter-types"></a>6.9.3. MODULE TYPES PROVIDED</h3></div></div></div><p>
      All module types (<code class="option">auth</code>, <code class="option">account</code>,
      <code class="option">password</code> and <code class="option">session</code>) are provided.
    </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_filter-return_values"></a>6.9.4. RETURN VALUES</h3></div></div></div><p>
      </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">PAM_SUCCESS</span></dt><dd><p>
              The new filter was set successfully.
            </p></dd><dt><span class="term">PAM_ABORT</span></dt><dd><p>
	      Critical error, immediate abort.
            </p></dd></dl></div><p>
    </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_filter-examples"></a>6.9.5. EXAMPLES</h3></div></div></div><p>
      Add the following line to <code class="filename">/etc/pam.d/login</code> to
      see how to configure login to transpose upper and lower case letters
      once the user has logged in:

      </p><pre class="programlisting">
        session required pam_filter.so run1 /lib/security/pam_filter/upperLOWER
      </pre><p>
    </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_filter-author"></a>6.9.6. AUTHOR</h3></div></div></div><p>
        pam_filter was written by Andrew G. Morgan &lt;morgan@kernel.org&gt;.
      </p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sag-pam_faildelay.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sag-module-reference.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sag-pam_ftp.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">6.8. pam_faildelay - change the delay on failure per-application </td><td width="20%" align="center"><a accesskey="h" href="Linux-PAM_SAG.html">Home</a></td><td width="40%" align="right" valign="top"> 6.10. pam_ftp - module for anonymous access</td></tr></table></div></body></html>