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<!DOCTYPE document [
  <!ENTITY project SYSTEM "project.xml">
]>
<document url="valve.html">

  &project;

  <properties>
    <author email="craigmcc@apache.org">Craig R. McClanahan</author>
    <title>The Valve Component</title>
  </properties>

<body>

<section name="Table of Contents">
<toc/>
</section>

<section name="Introduction">

  <p>A <strong>Valve</strong> element represents a component that will be
  inserted into the request processing pipeline for the associated
  Catalina container (<a href="engine.html">Engine</a>,
  <a href="host.html">Host</a>, or <a href="context.html">Context</a>).
  Individual Valves have distinct processing capabilities, and are
  described individually below.</p>

    <blockquote><em>
    <p>The description below uses the variable name $CATALINA_BASE to refer the
    base directory against which most relative paths are resolved. If you have
    not configured Tomcat 6 for multiple instances by setting a CATALINA_BASE
    directory, then $CATALINA_BASE will be set to the value of $CATALINA_HOME,
    the directory into which you have installed Tomcat 6.</p>
    </em></blockquote>

</section>


<section name="Access Log Valve">

  <subsection name="Introduction">

    <p>The <strong>Access Log Valve</strong> creates log files in the same
    format as those created by standard web servers.  These logs can later
    be analyzed by standard log analysis tools to track page hit counts,
    user session activity, and so on.  The files produces by this <code>Valve</code>
    are rolled over nightly at midnight.  This <code>Valve</code>
    may be associated with any Catalina container (<code>Context</code>,
    <code>Host</code>, or <code>Engine</code>), and
    will record ALL requests processed by that container.</p>

    <p>Some requests may be handled by Tomcat before they are passed to a
    container. These include redirects from /foo to /foo/ and the rejection of
    invalid requests. Where Tomcat can identify the <code>Context</code> that
    would have handled the request, the request/response will be logged in the 
    <code>AccessLog</code>(s) associated <code>Context</code>, <code>Host</code>
    and <code>Engine</code>. Where Tomcat cannot identify the
    <code>Context</code> that would have handled the request, e.g. in cases
    where the URL is invalid, Tomcat will look first in the <code>Engine</code>,
    then the default <code>Host</code> for the <code>Engine</code> and finally
    the ROOT (or default) <code>Context</code> for the default <code>Host</code>
    for an <code>AccessLog</code> implementation. Tomcat will use the first
    <code>AccessLog</code> implementation found to log those requests that are
    rejected before they are passed to a container.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Access Log Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.AccessLogValve</strong> to use the
        default access log valve.</p>
      </attribute>

      <attribute name="directory" required="false">
        <p>Absolute or relative pathname of a directory in which log files
        created by this valve will be placed.  If a relative path is
        specified, it is interpreted as relative to $CATALINA_BASE.  If
        no directory attribute is specified, the default value is "logs"
        (relative to $CATALINA_BASE).</p>
      </attribute>

      <attribute name="encoding" required="false">
        <p>Character set used to write the log file. An empty string means
        to use the system default character set. Default value: use the
        system default character set.
        </p>
      </attribute>

      <attribute name="pattern" required="false">
        <p>A formatting layout identifying the various information fields
        from the request and response to be logged, or the word
        <code>common</code> or <code>combined</code> to select a
        standard format.  See below for more information on configuring
        this attribute. Note that the optimized access does only support
        <code>common</code> and <code>combined</code> as the value for this
        attribute.</p>
      </attribute>

      <attribute name="prefix" required="false">
        <p>The prefix added to the start of each log file's name.  If not
        specified, the default value is "access_log.".  To specify no prefix,
        use a zero-length string.</p>
      </attribute>

      <attribute name="resolveHosts" required="false">
        <p>Set to <code>true</code> to convert the IP address of the remote
        host into the corresponding host name via a DNS lookup.  Set to
        <code>false</code> to skip this lookup, and report the remote IP
        address instead.</p>
      </attribute>

      <attribute name="suffix" required="false">
        <p>The suffix added to the end of each log file's name.  If not
        specified, the default value is "".  To specify no suffix,
        use a zero-length string.</p>
      </attribute>

      <attribute name="rotatable" required="false">
        <p>Flag to determine if log rotation should occur.
           If set to <code>false</code>, then this file is never rotated and
           <code>fileDateFormat</code> is ignored. Use with caution!
           Default value: <code>true</code>
        </p>
      </attribute>

      <attribute name="condition" required="false">
        <p>Turns on conditional logging. If set, requests will be
           logged only if <code>ServletRequest.getAttribute()</code> is
           null. For example, if this value is set to
           <code>junk</code>, then a particular request will only be logged
           if <code>ServletRequest.getAttribute("junk") == null</code>.
           The use of Filters is an easy way to set/unset the attribute
           in the ServletRequest on many different requests.
        </p>
      </attribute>

      <attribute name="fileDateFormat" required="false">
        <p>Allows a customized date format in the access log file name.
           The date format also decides how often the file is rotated.
           If you wish to rotate every hour, then set this value
           to: <code>yyyy-MM-dd.HH</code>
        </p>
      </attribute>

      <attribute name="buffered" required="false">
        <p>Flag to determine if logging will be buffered.
           If set to <code>false</code>, then access logging will be written after each 
           request. Default value: <code>true</code>
        </p>
      </attribute>

    </attributes>

    <p>Values for the <code>pattern</code> attribute are made up of literal
    text strings, combined with pattern identifiers prefixed by the "%"
    character to cause replacement by the corresponding variable value from
    the current request and response.  The following pattern codes are
    supported:</p>
    <ul>
    <li><b>%a</b> - Remote IP address</li>
    <li><b>%A</b> - Local IP address</li>
    <li><b>%b</b> - Bytes sent, excluding HTTP headers, or '-' if zero</li>
    <li><b>%B</b> - Bytes sent, excluding HTTP headers</li>
    <li><b>%h</b> - Remote host name (or IP address if
        <code>resolveHosts</code> is false)</li>
    <li><b>%H</b> - Request protocol</li>
    <li><b>%l</b> - Remote logical username from identd (always returns
        '-')</li>
    <li><b>%m</b> - Request method (GET, POST, etc.)</li>
    <li><b>%p</b> - Local port on which this request was received</li>
    <li><b>%q</b> - Query string (prepended with a '?' if it exists)</li>
    <li><b>%r</b> - First line of the request (method and request URI)</li>
    <li><b>%s</b> - HTTP status code of the response</li>
    <li><b>%S</b> - User session ID</li>
    <li><b>%t</b> - Date and time, in Common Log Format</li>
    <li><b>%u</b> - Remote user that was authenticated (if any), else '-'</li>
    <li><b>%U</b> - Requested URL path</li>
    <li><b>%v</b> - Local server name</li>
    <li><b>%D</b> - Time taken to process the request, in millis</li>
    <li><b>%T</b> - Time taken to process the request, in seconds</li>
    <li><b>%I</b> - Current request thread name (can compare later with stacktraces)</li>
    </ul>

    <p>
    There is also support to write information from the cookie, incoming
    header, the Session or something else in the ServletRequest.
    It is modeled after the
    <a href="http://httpd.apache.org/">Apache HTTP Server</a> log configuration
    syntax:</p>
    <ul>
    <li><b><code>%{xxx}i</code></b> for incoming headers</li>
    <li><b><code>%{xxx}o</code></b> for outgoing response headers</li>
    <li><b><code>%{xxx}c</code></b> for a specific cookie</li>
    <li><b><code>%{xxx}r</code></b> xxx is an attribute in the ServletRequest</li>
    <li><b><code>%{xxx}s</code></b> xxx is an attribute in the HttpSession</li>
    </ul>


    <p>The shorthand pattern name <code>common</code> (which is also the
    default) corresponds to <strong>'%h %l %u %t "%r" %s %b'</strong>.</p>

    <p>The shorthand pattern name <code>combined</code> appends the
    values of the <code>Referer</code> and <code>User-Agent</code> headers,
    each in double quotes, to the <code>common</code> pattern
    described in the previous paragraph.</p>

    <p>When Tomcat is operating behind a reverse proxy, the client information
    logged by the Access Log Valve may represent the reverse proxy, the browser
    or some combination of the two depending on the configuration of Tomcat and
    the reverse proxy. For Tomcat configuration options see the
    <a href="../proxy-howto.html">Proxy How-To</a>. For reverse proxies that
    use mod_jk, see the <a
    href="http://tomcat.apache.org/connectors-doc/generic_howto/proxy.html">generic
    proxy</a> documentation. For other reverse proxies, consult their
    documentation.</p>
  </subsection>

</section>


<section name="Remote Address Filter">

  <subsection name="Introduction">

    <p>The <strong>Remote Address Filter</strong> allows you to compare the
    IP address of the client that submitted this request against one or more
    <em>regular expressions</em>, and either allow the request to continue
    or refuse to process the request from this client.  A Remote Address
    Filter can be associated with any Catalina container
    (<a href="engine.html">Engine</a>, <a href="host.html">Host</a>, or
    <a href="context.html">Context</a>), and must accept any request
    presented to this container for processing before it will be passed on.</p>

    <p>The syntax for <em>regular expressions</em> is different than that for
    'standard' wildcard matching. Tomcat uses the <code>java.util.regex</code>
    package. Please consult the Java documentation for details of the
    expressions supported.</p>

    <p>Optionally one can append the server connector port separated with a
    comma (";") to allow different expressions for each connector.</p>

    <p>See also: <a href="#Remote_Host_Filter">Remote Host Filter</a>,
    <a href="#Remote_IP_Valve">Remote IP Valve</a>.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Remote Address Filter</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.RemoteAddrValve</strong>.</p>
      </attribute>

      <attribute name="allow" required="false">
        <p>A comma-separated list of <em>regular expression</em> patterns
        that the remote client's IP address is compared to.  If this attribute
        is specified, the remote address MUST match for this request to be
        accepted.  If this attribute is not specified, all requests will be
        accepted UNLESS the remote address matches a <code>deny</code>
        pattern.</p>
      </attribute>

      <attribute name="deny" required="false">
        <p>A comma-separated list of <em>regular expression</em> patterns
        that the remote client's IP address is compared to.  If this attribute
        is specified, the remote address MUST NOT match for this request to be
        accepted.  If this attribute is not specified, request acceptance is
        governed solely by the <code>allow</code> attribute.</p>
      </attribute>

      <attribute name="denyStatus" required="false">
        <p>HTTP response status code that is used when rejecting denied
        request. The default value is <code>403</code>. For example,
        it can be set to the value <code>404</code>.</p>
      </attribute>

      <attribute name="addConnectorPort" required="false">
        <p>Append the server connector port to the client IP address separated
        with a semicolon (";"). If this is set to <code>true</code>, the
        expressions configured with <code>allow</code> and
        <code>deny</code> is compared against <code>ADDRESS;PORT</code>
        where <code>ADDRESS</code> is the client IP address and
        <code>PORT</code> is the Tomcat connector port which received the
        request. The default value is <code>false</code>.</p>
      </attribute>

    </attributes>

  </subsection>

  <subsection name="Example">
    <p>To allow unrestricted access for the clients connecting from localhost
    but for all other clients only to port 8443:</p>
    <source><![CDATA[<Valve className="org.apache.catalina.valves.RemoteAddrValve"
   addConnectorPort="true"
   allow="127\.\d+\.\d+\.\d+;\d*,::1;\d*,0:0:0:0:0:0:0:1;\d*,.*;8443"/>]]></source>
  </subsection>

</section>


<section name="Remote Host Filter">

  <subsection name="Introduction">

    <p>The <strong>Remote Host Filter</strong> allows you to compare the
    hostname of the client that submitted this request against one or more
    <em>regular expressions</em>, and either allow the request to continue
    or refuse to process the request from this client.  A Remote Host
    Filter can be associated with any Catalina container
    (<a href="engine.html">Engine</a>, <a href="host.html">Host</a>, or
    <a href="context.html">Context</a>), and must accept any request
    presented to this container for processing before it will be passed on.</p>

    <p>The syntax for <em>regular expressions</em> is different than that for
    'standard' wildcard matching. Tomcat uses the <code>java.util.regex</code>
    package. Please consult the Java documentation for details of the
    expressions supported.</p>

    <p>Optionally one can append the server connector port separated with a
    comma (";") to allow different expressions for each connector.</p>

    <p><strong>Note:</strong> This filter processes the value returned by
    method <code>ServletRequest.getRemoteHost()</code>. To allow the method
    to return proper host names, you have to enable "DNS lookups" feature on
    a <strong>Connector</strong>.</p>

    <p>See also: <a href="#Remote_Address_Filter">Remote Address Filter</a>,
    <a href="http.html">HTTP Connector</a> configuration.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Remote Host Filter</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.RemoteHostValve</strong>.</p>
      </attribute>

      <attribute name="allow" required="false">
        <p>A comma-separated list of <em>regular expression</em> patterns
        that the remote client's hostname is compared to.  If this attribute
        is specified, the remote hostname MUST match for this request to be
        accepted.  If this attribute is not specified, all requests will be
        accepted UNLESS the remote hostname matches a <code>deny</code>
        pattern.</p>
      </attribute>

      <attribute name="deny" required="false">
        <p>A comma-separated list of <em>regular expression</em> patterns
        that the remote client's hostname is compared to.  If this attribute
        is specified, the remote hostname MUST NOT match for this request to be
        accepted.  If this attribute is not specified, request acceptance is
        governed solely by the <code>allow</code> attribute.</p>
      </attribute>

      <attribute name="denyStatus" required="false">
        <p>HTTP response status code that is used when rejecting denied
        request. The default value is <code>403</code>. For example,
        it can be set to the value <code>404</code>.</p>
      </attribute>

      <attribute name="addConnectorPort" required="false">
        <p>Append the server connector port to the client hostname separated
        with a comma (";"). If this is set to <code>true</code>, the
        expressions configured with <code>allow</code> and
        <code>deny</code> is compared against <code>HOSTNAME;PORT</code>
        where <code>HOSTNAME</code> is the client hostname and
        <code>PORT</code> is the Tomcat connector port which received the
        request. The default value is <code>false</code>.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Request Dumper Valve">


  <subsection name="Introduction">

    <p>The <em>Request Dumper Valve</em> is a useful tool in debugging
    interactions with a client application (or browser) that is sending
    HTTP requests to your Tomcat-based server.  When configured, it causes
    details about each request processed by its associated <code>Engine</code>, 
    <code>Host</code>, or <code>Context</code> to be logged according to 
    the logging configuration for that container.</p>

    <p><strong>WARNING: Using this valve has side-effects.</strong>  The
    output from this valve includes any parameters included with the request.
    The parameters will be decoded using the default platform encoding. Any
    subsequent calls to <code>request.setCharacterEncoding()</code> within
    the web application will have no effect. NOTE: Since all parameters are
    included in the output, the InputStream is consumed for requests made with
    the method POST and content-type application/x-www-form-urlencoded.</p>

  </subsection>


  <subsection name="Attributes">

    <p>The <strong>Request Dumper Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.RequestDumperValve</strong>.</p>
      </attribute>

    </attributes>

  </subsection>


</section>


<section name="Single Sign On Valve">

  <subsection name="Introduction">

    <p>The <em>Single Sign On Valve</em> is utilized when you wish to give users
    the ability to sign on to any one of the web applications associated with
    your virtual host, and then have their identity recognized by all other
    web applications on the same virtual host.</p>

    <p>See the <a href="host.html#Single Sign On">Single Sign On</a> special
    feature on the <strong>Host</strong> element for more information.</p>

  </subsection>


  <subsection name="Attributes">

    <p>The <strong>Single Sign On</strong> Valve supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.authenticator.SingleSignOn</strong>.</p>
      </attribute>

      <attribute name="requireReauthentication" required="false">
        <p>Default false. Flag to determine whether each request needs to be 
        reauthenticated to the security <strong>Realm</strong>. If "true", this
        Valve uses cached security credentials (username and password) to
        reauthenticate to the <strong>Realm</strong> each request associated 
        with an SSO session.  If "false", the Valve can itself authenticate 
        requests based on the presence of a valid SSO cookie, without 
        rechecking with the <strong>Realm</strong>.</p>
      </attribute>
 
      <attribute name="cookieDomain" required="false">
        <p>Sets the host domain to be used for sso cookies.</p>
      </attribute>
      
    </attributes>

  </subsection>


</section>


<section name="Basic Authenticator Valve">

  <subsection name="Introduction">

    <p>The <strong>Basic Authenticator Valve</strong> is automatically added to
    any <a href="context.html">Context</a> that is configured to use BASIC
    authentication.</p>

    <p>If any non-default settings are required, the valve may be configured
    within <a href="context.html">Context</a> element with the required
    values.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Basic Authenticator Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.authenticator.BasicAuthenticator</strong>.</p>
      </attribute>

      <attribute name="changeSessionIdOnAuthentication" required="false">
        <p>Controls if the session ID is changed if a session exists at the
        point where users are authenticated. This is to prevent session fixation
        attacks. If not set, the default value of <code>true</code> will be
        used.</p>
      </attribute>

      <attribute name="disableProxyCaching" required="false">
        <p>Controls the caching of pages that are protected by security
        constraints. Setting this to <code>false</code> may help work around
        caching issues in some browsers but will also cause secured pages to be
        cached by proxies which will almost certainly be a security issue.
        <code>securePagesWithPragma</code> offers an alternative, secure,
        workaround for browser caching issues. If not set, the default value of
        <code>true</code> will be used.</p>
      </attribute>

      <attribute name="securePagesWithPragma" required="false">
        <p>Controls the caching of pages that are protected by security
        constraints. Setting this to <code>false</code> may help work around
        caching issues in some browsers by using
        <code>Cache-Control: private</code> rather than the default of
        <code>Pragma: No-cache</code> and <code>Cache-control: No-cache</code>.
        If not set, the default value of <code>true</code> will be used.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Digest Authenticator Valve">

  <subsection name="Introduction">

    <p>The <strong>Digest Authenticator Valve</strong> is automatically added to
    any <a href="context.html">Context</a> that is configured to use DIGEST
    authentication.</p>

    <p>If any non-default settings are required, the valve may be configured
    within <a href="context.html">Context</a> element with the required
    values.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Digest Authenticator Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="cache" required="false">
        <p>Should we cache authenticated Principals if the request is part of an
        HTTP session? If not specified, the default value of <code>false</code>
        will be used.</p>
      </attribute>
      
      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.authenticator.DigestAuthenticator</strong>.</p>
      </attribute>

      <attribute name="changeSessionIdOnAuthentication" required="false">
        <p>Controls if the session ID is changed if a session exists at the
        point where users are authenticated. This is to prevent session fixation
        attacks. If not set, the default value of <code>true</code> will be
        used.</p>
      </attribute>

      <attribute name="disableProxyCaching" required="false">
        <p>Controls the caching of pages that are protected by security
        constraints. Setting this to <code>false</code> may help work around
        caching issues in some browsers but will also cause secured pages to be
        cached by proxies which will almost certainly be a security issue.
        <code>securePagesWithPragma</code> offers an alternative, secure,
        workaround for browser caching issues. If not set, the default value of
        <code>true</code> will be used.</p>
      </attribute>

      <attribute name="key" required="false">
        <p>The secret key used by digest authentication. If not set, a secure
        random value is generated. This should normally only be set when it is
        necessary to keep key values constant either across server restarts
        and/or across a cluster.</p>
      </attribute>

      <attribute name="nonceCacheSize" required="false">
        <p>To protect against replay attacks, the DIGEST authenticator tracks
        server nonce and nonce count values. This attribute controls the size
        of that cache. If not specified, the default value of 1000 is used.</p>
      </attribute>

      <attribute name="nonceValidity" required="false">
        <p>The time, in milliseconds, that a server generated nonce will be
        considered valid for use in authentication. If not specified, the
        default value of 300000 (5 minutes) will be used.</p>
      </attribute>

      <attribute name="opaque" required="false">
        <p>The opaque server string used by digest authentication. If not set, a
        random value is generated. This should normally only be set when it is
        necessary to keep opaque values constant either across server restarts
        and/or across a cluster.</p>
      </attribute>
      
      <attribute name="securePagesWithPragma" required="false">
        <p>Controls the caching of pages that are protected by security
        constraints. Setting this to <code>false</code> may help work around
        caching issues in some browsers by using
        <code>Cache-Control: private</code> rather than the default of
        <code>Pragma: No-cache</code> and <code>Cache-control: No-cache</code>.
        If not set, the default value of <code>true</code> will be used.</p>
      </attribute>

      <attribute name="validateUri" required="false">
        <p>Should the URI be validated as required by RFC2617? If not specified,
        the default value of <code>true</code> will be used. This should
        normally only be set when Tomcat is located behind a reverse proxy and
        the proxy is modifying the URI passed to Tomcat such that DIGEST
        authentication always fails.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Form Authenticator Valve">

  <subsection name="Introduction">

    <p>The <strong>Form Authenticator Valve</strong> is automatically added to
    any <a href="context.html">Context</a> that is configured to use FORM
    authentication.</p>

    <p>If any non-default settings are required, the valve may be configured
    within <a href="context.html">Context</a> element with the required
    values.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Form Authenticator Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.authenticator.FormAuthenticator</strong>.</p>
      </attribute>

      <attribute name="changeSessionIdOnAuthentication" required="false">
        <p>Controls if the session ID is changed if a session exists at the
        point where users are authenticated. This is to prevent session fixation
        attacks. If not set, the default value of <code>true</code> will be
        used.</p>
      </attribute>

      <attribute name="characterEncoding" required="false">
        <p>Character encoding to use to read the username and password parameters
        from the request. If not set, the encoding of the request body will be
        used.</p>
      </attribute>
      
      <attribute name="disableProxyCaching" required="false">
        <p>Controls the caching of pages that are protected by security
        constraints. Setting this to <code>false</code> may help work around
        caching issues in some browsers but will also cause secured pages to be
        cached by proxies which will almost certainly be a security issue.
        <code>securePagesWithPragma</code> offers an alternative, secure,
        workaround for browser caching issues. If not set, the default value of
        <code>true</code> will be used.</p>
      </attribute>

      <attribute name="securePagesWithPragma" required="false">
        <p>Controls the caching of pages that are protected by security
        constraints. Setting this to <code>false</code> may help work around
        caching issues in some browsers by using
        <code>Cache-Control: private</code> rather than the default of
        <code>Pragma: No-cache</code> and <code>Cache-control: No-cache</code>.
        If not set, the default value of <code>true</code> will be used.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="SSL Authenticator Valve">

  <subsection name="Introduction">

    <p>The <strong>SSL Authenticator Valve</strong> is automatically added to
    any <a href="context.html">Context</a> that is configured to use SSL
    authentication.</p>

    <p>If any non-default settings are required, the valve may be configured
    within <a href="context.html">Context</a> element with the required
    values.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>SSL Authenticator Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.authenticator.SSLAuthenticator</strong>.</p>
      </attribute>

      <attribute name="changeSessionIdOnAuthentication" required="false">
        <p>Controls if the session ID is changed if a session exists at the
        point where users are authenticated. This is to prevent session fixation
        attacks. If not set, the default value of <code>true</code> will be
        used.</p>
      </attribute>

      <attribute name="disableProxyCaching" required="false">
        <p>Controls the caching of pages that are protected by security
        constraints. Setting this to <code>false</code> may help work around
        caching issues in some browsers but will also cause secured pages to be
        cached by proxies which will almost certainly be a security issue.
        <code>securePagesWithPragma</code> offers an alternative, secure,
        workaround for browser caching issues. If not set, the default value of
        <code>true</code> will be used.</p>
      </attribute>

      <attribute name="securePagesWithPragma" required="false">
        <p>Controls the caching of pages that are protected by security
        constraints. Setting this to <code>false</code> may help work around
        caching issues in some browsers by using
        <code>Cache-Control: private</code> rather than the default of
        <code>Pragma: No-cache</code> and <code>Cache-control: No-cache</code>.
        If not set, the default value of <code>true</code> will be used.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="WebDAV Fix Valve">

  <subsection name="Introduction">

    <p>Microsoft operating systems have two WebDAV clients. One is used with
    port 80, the other is used for all other ports. The implementation used with
    port 80 does not adhere to the WebDAV specification and fails when trying to
    communicate with the Tomcat WebDAV Servlet. This valve provides a fix for
    this by forcing the use of the WebDAV implementation that works, even when
    connecting via port 80.</p>
    
    <p>This Valve may be used at the <code>Engine</code>, <code>Host</code> or
    <code>Context</code> level as required. Normally, this Valve would be used
    at the <code>Context</code> level.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>WebDAV Fix Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.WebdavFixValve</strong>.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Remote IP Valve">

  <subsection name="Introduction">
  
    <p>Tomcat port of
    <a href="http://httpd.apache.org/docs/trunk/mod/mod_remoteip.html">mod_remoteip</a>,
    this valve replaces the apparent client remote IP address and hostname for
    the request with the IP address list presented by a proxy or a load balancer
    via a request headers (e.g. &quot;X-Forwarded-For&quot;).</p>

    <p>Another feature of this valve is to replace the apparent scheme
    (http/https), server port and <code>request.secure</code> with the scheme presented 
    by a proxy or a load balancer via a request header 
    (e.g. &quot;X-Forwarded-Proto&quot;).</p>
    
    <p>This Valve may be used at the <code>Engine</code>, <code>Host</code> or
    <code>Context</code> level as required. Normally, this Valve would be used
    at the <code>Engine</code> level.</p>
    
    <p>If used in conjunction with Remote Address/Host valves then this valve
    should be defined first to ensure that the correct client IP address is
    presented to the Remote Address/Host valves.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Remote IP Valve</strong> supports the
    following configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.RemoteIpValve</strong>.</p>
      </attribute>

      <attribute name="remoteIpHeader" required="false">
        <p>Name of the HTTP Header read by this valve that holds the list of
        traversed IP addresses starting from the requesting client. If not
        specified, the default of <code>x-forwarded-for</code> is used.</p>
      </attribute>

      <attribute name="internalProxies" required="false">
        <p>List of internal proxies' IP addresses as comma separated regular
        expressions. If they appear in the <strong>remoteIpHeader</strong>
        value, they will be trusted and will not appear in the
        <strong>proxiesHeader</strong> value. If not specified the default value
        of <code>10\.\d\d?\d?\.\d\d?\d?\.\d\d?\d?,
        192\.168\.\d\d?\d?\.\d\d?\d?,
        169\.254\.\d\d?\d?\.\d\d?\d?,
        127\.\d\d?\d?\.\d\d?\d?\.\d\d?\d?</code> will
        be used.</p>
        <p>
          Note that the individual regular expressions <i>must not</i>
          contain commas themselves, as the <code>internalProxies</code>
          value is first split by commas, then parsed into separate regular
          expression patterns.
        </p>
      </attribute>

      <attribute name="proxiesHeader" required="false">
        <p>Name of the HTTP header created by this valve to hold the list of
        proxies that have been processed in the incoming
        <strong>remoteIpHeader</strong>. If not specified, the default of
        <code>x-forwarded-by</code> is used.</p>
      </attribute>

      <attribute name="trustedProxies" required="false">
        <p>List of trusted proxies' IP addresses as comma separated regular
        expressions. If they appear in the <strong>remoteIpHeader</strong>
        value, they will be trusted and will appear in the
        <strong>proxiesHeader</strong> value. If not specified, no proxies will
        be trusted.</p>
      </attribute>

      <attribute name="protocolHeader" required="false">
        <p>Name of the HTTP Header read by this valve that holds the protocol
        used by the client to connect to the proxy. If not specified, the
        default of <code>null</code> is used.</p>
      </attribute>

      <attribute name="protocolHeaderHttpsValue" required="false">
        <p>Value of the <strong>protocolHeader</strong> to indicate that it is
        an HTTPS request. If not specified, the default of <code>https</code> is
        used.</p>
      </attribute>

      <attribute name="httpServerPort" required="false">
         <p>Value returned by <code>ServletRequest.getServerPort()</code> 
         when the <strong>protocolHeader</strong> indicates <code>http</code> 
         protocol. If not specified, the default of <code>80</code> is
        used.</p>
      </attribute>

      <attribute name="httpsServerPort" required="false">
         <p>Value returned by <code>ServletRequest.getServerPort()</code> 
         when the <strong>protocolHeader</strong> indicates <code>https</code> 
         protocol. If not specified, the default of <code>443</code> is
        used.</p>
      </attribute>
      
    </attributes>

  </subsection>

</section>


<section name="Stuck Thread Detection Valve">

  <subsection name="Introduction">

    <p>This valve allows to detect requests that take a long time to process, which might
    indicate that the thread that is processing it is stuck.</p>
    <p>When such a request is detected, the current stack trace of its thread is written
    to Tomcat log with a WARN level.</p>
    <p>The IDs and names of the stuck threads are available through JMX in the
    <code>stuckThreadIds</code> and <code>stuckThreadNames</code> attributes.
    The IDs can be used with the standard Threading JVM MBean
    (<code>java.lang:type=Threading</code>) to retrieve other information
    about each stuck thread.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Stuck Thread Detection Valve</strong> supports the
    following configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.StuckThreadDetectionValve</strong>.
        </p>
      </attribute>

      <attribute name="threshold" required="false">
        <p>Minimum duration in seconds after which a thread is considered stuck.
        Default is 600 seconds. If set to 0, the detection is disabled.</p>
        <p>Note: since the detection is done in the background thread of the Container
        (Engine, Host or Context) declaring this Valve, the threshold should be higher
        than the <code>backgroundProcessorDelay</code> of this Container.</p>
      </attribute>

    </attributes>

  </subsection>

</section>

<section name="SSL Valve">

  <subsection name="Introduction">

    <p>When using mod_proxy_http, the client SSL information is not included in
    the protocol (unlike mod_jk and mod_proxy_ajp). To make the client SSL
    information available to Tomcat, some additional configuration is required.
    In httpd, mod_headers is used to add the SSL information as HTTP headers. In
    Tomcat, this valve is used to read the information from the HTTP headers and
    insert it into the request.</p>

    <p>Note: Ensure that the headers are always set by httpd for all requests to
    prevent a client spoofing SSL information by sending fake headers.</p>

    <p>To configure httpd to set the necessary headers, add the following:</p>
<source>&lt;IfModule ssl_module&gt;
  RequestHeader set SSL_CLIENT_CERT "%{SSL_CLIENT_CERT}s"
  RequestHeader set SSL_CIPHER "%{SSL_CIPHER}s"
  RequestHeader set SSL_SESSION_ID "%{SSL_SESSION_ID}s"
  RequestHeader set SSL_CIPHER_USEKEYSIZE "%{SSL_CIPHER_USEKEYSIZE}s"
&lt;/IfModule&gt;</source>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>SSL Valve</strong> supports the following configuration
    attribute:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.SSLValve</strong>.
        </p>
      </attribute>

    </attributes>

  </subsection>

</section>
<section name="Semaphore Valve">

  <subsection name="Introduction">

    <p>The <strong>Semaphore Valve</strong> is able to limit the number of
    concurrent request processing threads.</p>
    <p><strong>org.apache.catalina.valves.SemaphoreValve</strong> provides
    methods which may be overridden by a subclass to customize behavior:</p>
    <ul>
    <li><b><code>controlConcurrency</code></b> may be overridden to add
    conditions;</li>
    <li><b><code>permitDenied</code></b> may be overridden to add error handling
    when a permit isn't granted.</li>
    </ul>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Semaphore Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="block" required="false">
        <p>Flag to determine if a thread is blocked until a permit is available.
        The default value is <strong>true</strong>.</p>
      </attribute>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use. This MUST be set to
        <strong>org.apache.catalina.valves.SemaphoreValve</strong>.</p>
      </attribute>

      <attribute name="concurrency" required="false">
        <p>Concurrency level of the semaphore. The default value is
        <strong>10</strong>.</p>
      </attribute>

      <attribute name="fairness" required="false">
        <p>Fairness of the semaphore. The default value is
        <strong>false</strong>.</p>
      </attribute>

      <attribute name="interruptible" required="false">
        <p>Flag to determine if a thread may be interrupted until a permit is
        available. The default value is <strong>false</strong>.</p>
      </attribute>

    </attributes>

  </subsection>

</section>

</body>


</document>
