docs/manual/mod/core.xml

<?xml version="1.0"?>
<!DOCTYPE xml:manual [ <!ENTITY nbsp "&#160;"> ]>
<?xml-stylesheet type="text/xsl" href="../style/manual.xsl"?>
<modulesynopsis>

<name>core</name>
<status>Core</status>
<description>Core Apache HTTP Server features that are always
available</description>

<directivesynopsis>
<name>AcceptPathInfo</name>
<description>Controls whether requests can contain trailing pathname information</description>    
<syntax>AcceptPathInfo On|Off|Default</syntax>
<default>AcceptPathInfo Default</default>
<contextlist><context>server config</context>
<context>virtual host</context><context>directory</context>
<context>.htaccess</context></contextlist>
<compatibility>Available in Apache 2.0.30 and later</compatibility>

<usage>

    <p>This directive controls whether requests that contain trailing
    pathname information that follows an actual filename (or
    non-existent file in an existing directory) will be accepted or
    rejected.  The trailing pathname information can be made
    available to scripts in the PATH_INFO environment variable.</p>

    <p>For example, assume the location <code>/test/</code> points to
    a directory that contains only the single file
    <code>here.html</code>.  Then requests for
    <code>/test/here.html/more</code> and
    <code>/test/nothere.html/more</code> both collect
    <code>/more</code> as PATH_INFO.</p>

    <p>The three possible arguments for the
    <directive>AcceptPathInfo</directive> directive are:</p>
    <dl>
    <dt><code>off</code></dt><dd>A request will only be accepted if it
    maps to a literal path that exists.  Therefore a request with
    trailing pathname information after the true filename such as
    <code>/test/here.html/more</code> in the above example will return
    a 404 NOT FOUND error.</dd>

    <dt><code>on</code></dt><dd>A request will be accepted if a
    leading path component maps to a file that exists.  The above
    example <code>/test/here.html/more</code> will be accepted if
    <code>/test/here.html</code> maps to a valid file.</dd>
    
    <dt><code>default</code></dt><dd>The treatment of requests with
    trailing pathname information is determined by the <a
    href="../handler.html">handler</a> responsible for the request.
    The core handler for normal files defaults to rejecting PATH_INFO.
    Handlers that serve scripts, such as <a
    href="mod_cgi.html">cgi-script</a> and <a
    href="mod_isapi.html">isapi-isa</a>, generally accept PATH_INFO by
    default.</dd>
    </dl>

    <p>The primary purpose of the <code>AcceptPathInfo</code>
    directive is to allow you to override the handler's choice of
    accepting or rejecting PATH_INFO.  This override is required, for
    example, when you use a <a href="../filter.html">filter</a>, such
    as <a href="mod_include.html">INCLUDES</a>, to generate content
    based on PATH_INFO.  The core handler would usually reject the
    request, so you can use the following configuration to enable
    such a script:</p>
<example>
&lt;Files "mypaths.shtml"&gt;<br />
    Options +Includes<br />
    SetOutputFilter INCLUDES<br />
    AcceptPathInfo on<br />
&lt;/Files&gt;
</example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AccessFileName</name>
<description>Sets the name of the .htaccess file</description>
<syntax>AccessFileName <em>filename</em> [<em>filename</em>] ...</syntax>
<default>AccessFileName .htaccess</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>When returning a document to the client the server looks for
    the first existing access control file from this list of names
    in every directory of the path to the document, if access
    control files are enabled for that directory. For example:</p>

<example>
AccessFileName .acl
</example>

    <p>before returning the document
    <code>/usr/local/web/index.html</code>, the server will read
    <code>/.acl</code>, <code>/usr/.acl</code>,
    <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
    for directives, unless they have been disabled with</p>

<example>
&lt;Directory /&gt;<br />
&nbsp;&nbsp;AllowOverride None<br />
&lt;/Directory&gt;
</example>
</usage>
<seealso><directive module="core">AllowOverride</directive></seealso>
<seealso><a href="../configuring.html">Configuration Files</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>AddDefaultCharset</name>
<description>Specifies the default character set to be added for a
response without an explicit character set</description>
<syntax>AddDefaultCharset On|Off|<em>charset</em></syntax>
<contextlist><context>server config</context>
<context>virtual host</context><context>directory</context>
<context>.htaccess</context></contextlist>
<default>AddDefaultCharset Off</default>

<usage>

    <p>This directive specifies the name of the character set that
    will be added to any response that does not have any parameter on
    the content type in the HTTP headers. This will override any
    character set specified in the body of the document via a
    <code>META</code> tag. A setting of <code>AddDefaultCharset
    Off</code> disables this
    functionality. <code>AddDefaultCharset On</code> enables
    Apache's internal default charset of <code>iso-8859-1</code> as
    required by the directive. You can also specify an alternate
    <em>charset</em> to be used. For example:</p>

<example>
    AddDefaultCharset utf-8
</example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AddModule</name>
<syntax>AddModule <em>module</em> [<em>module</em>] ...</syntax>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>The server can have modules compiled in which are not
    actively in use. This directive can be used to enable the use
    of those modules. The server comes with a pre-loaded list of
    active modules; this list can be cleared with the <directive
    module="core">ClearModuleList</directive> directive.</p>

    <p>For example:</p>
<example>
AddDefaultCharset utf-8
</example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AllowOverride</name>
<description>Sets the types of directives that are allowed in
.htaccess files</description>
<syntax>AllowOverride All|None|<em>directive-type</em> [<em>directive-type</em>] ...</syntax>
<default>AllowOverride All</default>
<contextlist><context>directory</context></contextlist>

<usage>
    <p>When the server finds an .htaccess file (as specified by <directive
    module="core">AccessFileName</directive>) it needs to know
    which directives declared in that file can override earlier
    access information.</p>

    <p>When this directive is set to <code>None</code>, then
    .htaccess files are completely ignored. In this case, the
    server will not even attempt to read .htaccess files in the
    filesystem.</p>

    <p>When this directive is set to <code>All</code>, then any
    directive which has the .htaccess <a
    href="directive-dict.html#Context">Context</a> is allowed in
    .htaccess files.</p>

    <p>The <em>directive-type</em> can be one of the following
    groupings of directives.</p>

    <dl>
      <dt>AuthConfig</dt>

      <dd>

      Allow use of the authorization directives (<directive
      module="mod_auth_dbm">AuthDBMGroupFile</directive>,
      <directive module="mod_auth_dbm">AuthDBMUserFile</directive>,
      <directive module="mod_auth">AuthGroupFile</directive>,
      <directive module="core">AuthName</directive>, 
      <directive module="core">AuthType</directive>, <directive
      module="mod_auth">AuthUserFile</directive>, <directive
      module="core">Require</directive>, <em>etc.</em>).</dd>

      <dt>FileInfo</dt>

      <dd>
      Allow use of the directives controlling document types (<directive
      module="core">DefaultType</directive>, <directive
      module="core">ErrorDocument</directive>, <directive
      module="core">ForceType</directive>, <directive
      module="mod_negotiation">LanguagePriority</directive>,
      <directive module="core">SetHandler</directive>, <directive
      module="core">SetInputFilter</directive>, <directive
      module="core">SetOutputFilter</directive>, and 
      <module>mod_mime</module> Add* and Remove*
      directives, <em>etc.</em>).</dd>

      <dt>Indexes</dt>

      <dd>
      Allow use of the directives controlling directory indexing
      (<directive
      module="mod_autoindex">AddDescription</directive>,
      <directive module="mod_autoindex">AddIcon</directive>, <directive
      module="mod_autoindex">AddIconByEncoding</directive>,
      <directive module="mod_autoindex">AddIconByType</directive>,
      <directive module="mod_autoindex">DefaultIcon</directive>, <directive
      module="mod_dir">DirectoryIndex</directive>, <directive
      module="mod_autoindex">FancyIndexing</directive>, <directive
      module="mod_autoindex">HeaderName</directive>, <directive
      module="mod_autoindex">IndexIgnore</directive>, <directive
      module="mod_autoindex">IndexOptions</directive>, <directive
      module="mod_autoindex">ReadmeName</directive>,
      <em>etc.</em>).</dd>

      <dt>Limit</dt>

      <dd>
      Allow use of the directives controlling host access (<directive
      module="mod_access">Allow</directive>, <directive
      module="mod_access">Deny</directive> and <directive
      module="mod_access">Order</directive>).</dd>

      <dt>Options</dt>

      <dd>
      Allow use of the directives controlling specific directory
      features (<directive module="core">Options</directive> and
      <directive module="mod_include">XBitHack</directive>).</dd>
    </dl>

    <p>Example:</p>

    <example>AllowOverride AuthConfig Indexes</example>
</usage>

<seealso><directive module="core">AccessFileName</directive></seealso>
<seealso><a href="../configuring.html">Configuration Files</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>AuthName</name>
<description>Sets the authorization realm for use in HTTP
authentication</description>
<syntax>AuthName <em>auth-domain</em></syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>This directive sets the name of the authorization realm for a
    directory. This realm is given to the client so that the user
    knows which username and password to send.
    <directive>AuthName</directive> takes a single argument; if the
    realm name contains spaces, it must be enclosed in quotation
    marks.  It must be accompanied by <directive
    module="core">AuthType</directive> and <directive
    module="core">Require</directive> directives, and directives such
    as <directive module="mod_auth">AuthUserFile</directive> and
    <directive module="mod_auth">AuthGroupFile</directive> to
    work.</p>

   <p>For example:</p>

   <example>AuthName "Top Secret"</example>

    <p>The string provided for the <code>AuthRealm</code> is what will
    appear in the password dialog provided by most browsers.</p>
</usage>
<seealso><a 
    href="../howto/auth.html">Authentication, Authorization, and 
    Access Control</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>AuthType</name>
<description>Selects the type of user authentication</description>
<syntax>AuthType Basic|Digest</syntax>
<contextlist><context>directory</context><context>.htaccess</context>
<override>AuthConfig</override></contextlist>

<usage>
    <p>This directive selects the type of user authentication for a
    directory. Only <code>Basic</code> and <code>Digest</code> are
    currently implemented. 

     It must be accompanied by <directive
     module="core">AuthName</directive> and <directive
     module="core">Require</directive> directives, and directives such
     as <directive module="mod_auth">AuthUserFile</directive> and
     <directive module="mod_auth">AuthGroupFile</directive> to
     work.</p>
</usage>
<seealso><a href="../howto/auth.html">Authentication, Authorization,
and Access Control</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>ContentDigest</name>
<description>Enables the generation of Content-MD5 HTTP Response
headers</description> 
<syntax>ContentDigest on|off</syntax>
<default>ContentDigest off</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>Options</override>
<status>Experimental</status>
<compatibility>Available in Apache 1.1 and later</compatibility>

<usage>
    <p>This directive enables the generation of
    <code>Content-MD5</code> headers as defined in RFC1864
    respectively RFC2068.</p>

    <p>MD5 is an algorithm for computing a "message digest"
    (sometimes called "fingerprint") of arbitrary-length data, with
    a high degree of confidence that any alterations in the data
    will be reflected in alterations in the message digest.</p>

    <p>The <code>Content-MD5</code> header provides an end-to-end
    message integrity check (MIC) of the entity-body. A proxy or
    client may check this header for detecting accidental
    modification of the entity-body in transit. Example header:</p>
<example>
   Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
</example>

    <p>Note that this can cause performance problems on your server
    since the message digest is computed on every request (the
    values are not cached).</p>

    <p><code>Content-MD5</code> is only sent for documents served
    by the core, and not by any module. For example, SSI documents,
    output from CGI scripts, and byte range responses do not have
    this header.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>DefaultType</name>
<description>Sets the MIME content-type that will be sent if the
server cannot determine a type in any other way</description>
<syntax>DefaultType <em>MIME-type</em></syntax>
<default>DefaultType text/html</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>FileInfo</override>

<usage>
    <p>There will be times when the server is asked to provide a
    document whose type cannot be determined by its MIME types
    mappings.</p>

    <p>The server must inform the client of the content-type of the
    document, so in the event of an unknown type it uses the
    <code>DefaultType</code>. For example:</p>

<example>
      <code>DefaultType image/gif</code>
</example>
    would be appropriate for a directory which contained many gif
    images with filenames missing the .gif extension. 

    <p>Note that unlike <directive
    module="core">ForceType</directive>, this directive is only
    provides the default mime-type. All other mime-type definitions,
    including filename extensions, that might identify the media type
    will override this default.</p> 
</usage>
</directivesynopsis>

<directivesynopsis type="section">
<name>Directory</name>
<description>Enclose a group of directives that apply only to the
named file-system directory and sub-directories</description>
<syntax>&lt;Directory <em>directory-path</em>&gt;
... &lt;/Directory&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p><directive type="section">Directory</directive> and
    <code>&lt;/Directory&gt;</code> are used to enclose a group of
    directives which will apply only to the named directory and
    sub-directories of that directory. Any directive which is allowed
    in a directory context may be used.  <em>Directory-path</em> is
    either the full path to a directory, or a wild-card string. In a
    wild-card string, `?' matches any single character, and `*'
    matches any sequences of characters.  You may
    also use `[]' character ranges like in the shell. Also as of
    Apache 1.3 none of the wildcards match a `/' character, which more
    closely mimics the behavior of Unix shells. Example:</p>
<example>
   &lt;Directory /usr/local/httpd/htdocs&gt;<br />
&nbsp;&nbsp;Options Indexes FollowSymLinks<br />
   &lt;/Directory&gt;<br />
</example>

    <p>Extended regular
    expressions can also be used, with the addition of the
    <code>~</code> character. For example:</p>
<example>
   &lt;Directory ~ "^/www/.*/[0-9]{3}"&gt;
</example>
    would match directories in /www/ that consisted of three
    numbers. 

    <p>If multiple (non-regular expression) directory sections
    match the directory (or its parents) containing a document,
    then the directives are applied in the order of shortest match
    first, interspersed with the directives from the <a
    href="#accessfilename">.htaccess</a> files. For example,
    with</p>

<example>
      &lt;Directory /&gt;<br />
       &nbsp;&nbsp;AllowOverride None<br />
       &lt;/Directory&gt;<br />
      <br />
       &lt;Directory /home/*&gt;<br />
       &nbsp;&nbsp;AllowOverride FileInfo<br />
       &lt;/Directory&gt;
</example>
    <p>for access to the document <code>/home/web/dir/doc.html</code>
    the steps are:</p>

    <ul>
      <li>Apply directive <code>AllowOverride None</code>
      (disabling <code>.htaccess</code> files).</li>

      <li>Apply directive <code>AllowOverride FileInfo</code> (for
      directory <code>/home/web</code>).</li>

      <li>Apply any FileInfo directives in
      <code>/home/web/.htaccess</code></li>
    </ul>

    <p>Regular expressions are not considered until after all of the
    normal sections have been applied. Then all of the regular
    expressions are tested in the order they appeared in the
    configuration file. For example, with</p>

<example>&lt;Directory ~ abc$&gt;<br />
       ... directives here ...<br />
       &lt;/Directory&gt;<br />
</example>

    <p>The regular expression section won't be considered until after
    all normal &lt;Directory&gt;s and <code>.htaccess</code> files
    have been applied. Then the regular expression will match on
    <code>/home/abc/public_html/abc</code> and be applied.</p>

   <p><strong>Note that the default Apache access for
    &lt;Directory /&gt; is <samp>Allow from All</samp>. This means
    that Apache will serve any file mapped from an URL. It is
    recommended that you change this with a block such
    as</strong></p>

<example>
 &lt;Directory /&gt;<br />
     &nbsp;&nbsp;Order Deny,Allow<br />
     &nbsp;&nbsp;Deny from All<br />
 &lt;/Directory&gt;
</example>

    <p><strong>and then override this for directories you
    <em>want</em> accessible. See the <a
    href="../misc/security_tips.html">Security Tips</a> page for more
    details.</strong></p> 

    <p>The directory sections typically occur in
    the access.conf file, but they may appear in any configuration
    file.  <directive type="section">Directory</directive> directives
    cannot nest, and cannot appear in a <directive module="core"
    type="section">Limit</directive> or <directive module="core"
    type="section">LimitExcept</directive> section.</p>
</usage>
<seealso><a href="../sections.html">How
    Directory, Location and Files sections work</a> for an
    explanation of how these different sections are combined when a
    request is received</seealso>
</directivesynopsis>

<directivesynopsis type="section">
<name>DirectoryMatch</name>
<description>Enclose a group of directives that apply only to 
file-system directories that match a regular expression and their
subdirectories</description>
<syntax>&lt;Directory <em>regex</em>&gt;
... &lt;/Directory&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p><directive type="section">DirectoryMatch</directive> and
    <code>&lt;/DirectoryMatch&gt;</code> are used to enclose a group
    of directives which will apply only to the named directory and
    sub-directories of that directory, the same as <directive
    module="core" type="section">Directory</directive>. However, it
    takes as an argument a regular expression. For example:</p>
<example>
   &lt;DirectoryMatch "^/www/.*/[0-9]{3}"&gt;
</example>

    <p>would match directories in <code>/www/</code> that consisted of three
    numbers.</p>
</usage>
<seealso><directive type="section" module="core">Directory</directive> for
a description of how regular expressions are mixed in with normal
<code>&lt;Directory&gt;</code>s</seealso>
<seealso><a
href="../sections.html">How Directory, Location and Files sections
work</a> for an explanation of how these different sections are
combined when a request is received</seealso>
</directivesynopsis>

<directivesynopsis>
<name>DocumentRoot</name>
<description>Sets the directory that forms the main document tree visible
from the web</description>
<syntax>DocumentRoot <em>directory-path</em></syntax>
<default>DocumentRoot /usr/local/apache/htdocs</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>This directive sets the directory from which httpd will
    serve files. Unless matched by a directive like Alias, the
    server appends the path from the requested URL to the document
    root to make the path to the document. Example:</p>
<example>
   DocumentRoot /usr/web
</example>
    <p>then an access to
    <code>http://www.my.host.com/index.html</code> refers to
    <code>/usr/web/index.html</code>.</p>

    <p>The <directive>DocumentRoot</directive> should be specified without
    a trailing slash.</p>
</usage>
<seealso><a href="../urlmapping.html">Mapping URLs to Filesystem
Location</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>ErrorDocument</name>
<description>Specifies what the server will return to the client
in case of an error</description>
<syntax>ErrorDocument <em>error-code document</em></syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>FileInfo</override>
<compatibility>Quoting syntax for text messages is different in Apache
2.0</compatibility>

<usage>
    <p>In the event of a problem or error, Apache can be configured
    to do one of four things,</p>

    <ol>
      <li>output a simple hardcoded error message</li>

      <li>output a customized message</li>

      <li>redirect to a local <em>URL-path</em> to handle the
      problem/error</li>

      <li>redirect to an external <em>URL</em> to handle the
      problem/error</li>
    </ol>

    <p>The first option is the default, while options 2-4 are
    configured using the <directive>ErrorDocument</directive>
    directive, which is followed by the HTTP response code and a URL
    or a message. Apache will sometimes offer additional information
    regarding the problem/error.</p>

    <p>URLs can begin with a slash (/) for local URLs, or be a full
    URL which the client can resolve. Alternatively, a message can
    be provided to be displayed by the browser. Examples:</p>

<example>
      ErrorDocument 500
      http://foo.example.com/cgi-bin/tester<br />
       ErrorDocument 404 /cgi-bin/bad_urls.pl<br />
       ErrorDocument 401 /subscription_info.html<br />
       ErrorDocument 403 "Sorry can't allow you access
      today"
</example>

    <p>Note that when you specify an <directive>ErrorDocument</directive>
    that points to a remote URL (ie. anything with a method such as
    "http" in front of it), Apache will send a redirect to the
    client to tell it where to find the document, even if the
    document ends up being on the same server. This has several
    implications, the most important being that the client will not
    receive the original error status code, but instead will
    receive a redirect status code. This in turn can confuse web
    robots and other clients which try to determine if a URL is
    valid using the status code. In addition, if you use a remote
    URL in an <code>ErrorDocument 401</code>, the client will not
    know to prompt the user for a password since it will not
    receive the 401 status code. Therefore, <strong>if you use an
    "ErrorDocument 401" directive then it must refer to a local
    document.</strong></p>

    <p>Prior to version 2.0, messages were indicated by prefixing
    them with a single unmatched double quote character.</p>
</usage>

<seealso><a href="../custom-error.html">documentation of
    customizable responses</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>ErrorLog</name>
<description>Sets the name of the file to which the server
will log errors</description>    
<syntax> ErrorLog <em>file-path</em>|syslog[:<em>facility</em>]</syntax>
<default>ErrorLog logs/error_log (Unix)
ErrorLog logs/error.log (Windows and OS/2)</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>ErrorLog</directive> directive sets the name of
    the file to which the server will log any errors it encounters. If
    the <em>file-path</em> does not begin with a slash (/) then it is
    assumed to be relative to the <directive
    module="core">ServerRoot</directive>. If the <em>file-path</em>
    begins with a pipe (|) then it is assumed to be a command to spawn
    to handle the error log.</p>

    <p>Using <code>syslog</code> instead of a filename enables logging
    via syslogd(8) if the system supports it. The default is to use
    syslog facility <code>local7</code>, but you can override this by
    using the <code>syslog:</code><em>facility</em> syntax where
    <em>facility</em> can be one of the names usually documented in
    syslog(1).</p>

    <p>SECURITY: See the <a
    href="../misc/security_tips.html#serverroot">security tips</a>
    document for details on why your security could be compromised
    if the directory where logfiles are stored is writable by
    anyone other than the user that starts the server.</p>
</usage>
<seealso><directive module="core">LogLevel</directive></seealso>
<seealso><a href="../logs.html">Apache Log Files</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>FileETag</name>
<description>Configures the file attributes used to create the ETag
HTTP response header</description>
<syntax>FileETag <em>component</em> ...</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>FileInfo</override>

<usage>
    <p>
    The <directive>FileETag</directive> directive configures the file
    attributes that are used to create the ETag (entity tag) response
    header field when the document is based on a file.  (The ETag
    value is used in cache management to save network bandwidth.)  In
    Apache 1.3.22 and earlier, the ETag value was <em>always</em> formed
    from the file's inode, size, and last-modified time (mtime).  The
    FileETag directive allows you to choose which of these -- if any
    -- should be used.  The recognized keywords are:
    </p>
    <dl compact="compact">
     <dt><b>INode</b></dt>
     <dd>The file's i-node number will be included in the calculation</dd>
     <dt><b>MTime</b></dt>
     <dd>The date and time the file was last modified will be included</dd>
     <dt><b>Size</b></dt>
     <dd>The number of bytes in the file will be included</dd>
     <dt><b>All</b></dt>
     <dd>All available fields will be used (equivalent to
      '<code>FileETag&nbsp;INode&nbsp;MTime&nbsp;Size</code>')</dd>
     <dt><b>None</b></dt>
     <dd>If a document is file-based, no ETag field will be included in the
      response</dd>
    </dl>
    <p>
    The INode, MTime, and Size keywords may be prefixed with either '+'
    or '-', which allow changes to be made to the default setting
    inherited from a broader scope.  Any keyword appearing without
    such a prefix immediately and completely cancels the inherited
    setting.
    </p>
    <p>
    If a directory's configuration includes
    '<code>FileETag&nbsp;INode&nbsp;MTime&nbsp;Size</code>', and a
    subdirectory's includes '<code>FileETag&nbsp;-INode</code>',
    the setting for that subdirectory (which will be inherited by
    any sub-subdirectories that don't override it) will be equivalent to
    '<code>FileETag&nbsp;MTime&nbsp;Size</code>'.
    </p>
</usage>
</directivesynopsis>

<directivesynopsis type="section">
<name>Files</name>
<description>Contains that directives that apply to matched
filenames</description>
<syntax>&lt;Files <em>filename</em>&gt; ... &lt;/Files&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>The <directive type="section">Files</directive> directive
    provides for access control by filename. It is comparable to the
    <directive module="core" type="directive">Directory</directive>
    directive and <directive module="core"
    type="directive">Location</directive> directives. It should be
    matched with a <code>&lt;/Files&gt;</code> directive. The
    directives given within this section will be applied to any object
    with a basename (last component of filename) matching the
    specified filename. <directive type="section">Files</directive>
    sections are processed in the order they appear in the
    configuration file, after the <directive module="core"
    type="section">Directory</directive> sections and
    <code>.htaccess</code> files are read, but before <directive
    type="section" module="core">Location</directive> sections. Note
    that <directive type="section">Files</directive> can be nested
    inside <directive type="section"
    module="core">Directory</directive> sections to restrict the
    portion of the filesystem they apply to.</p>

    <p>The <em>filename</em> argument should include a filename, or
    a wild-card string, where `?' matches any single character, and
    `*' matches any sequences of characters. Extended regular
    expressions can also be used, with the addition of the
    <code>~</code> character. For example:</p>
<example>
   &lt;Files ~ "\.(gif|jpe?g|png)$"&gt;
</example>
    <p>would match most common Internet graphics formats. In Apache 1.3
    and later, <directive module="core"
    type="section">FilesMatch</directive> is preferred, however.</p>

    <p>Note that unlike <directive type="section"
    module="core">Directory</directive> and <directive type="section"
    module="core">Location</directive> sections, <directive
    type="section">Files</directive> sections can be used inside
    .htaccess files. This allows users to control access to their own
    files, at a file-by-file level.</p>

</usage>
<seealso><a href="../sections.html">How
    Directory, Location and Files sections work</a> for an
    explanation of how these different sections are combined when a
    request is received</seealso>
</directivesynopsis>

<directivesynopsis type="section">
<name>FilesMatch</name>
<description>Contains that directives that apply to regular-expression matched
filenames</description>
<syntax>&lt;FilesMatch <em>regex</em>&gt; ... &lt;/FilesMatch&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>The <directive type="section">FilesMatch</directive> directive
    provides for access control by filename, just as the <directive
    module="core" type="section">Files</directive> directive
    does. However, it accepts a regular expression. For example:</p>
<example>
   &lt;FilesMatch "\.(gif|jpe?g|png)$"&gt;
</example>

    <p>would match most common Internet graphics formats.</p>
</usage>

<seealso><a href="../sections.html">How
    Directory, Location and Files sections work</a> for an
    explanation of how these different sections are combined when a
    request is received</seealso>
</directivesynopsis>

<directivesynopsis>
<name>ForceType</name>
<description>Forces all matching files to be served with the specified
MIME content-type</description>
<syntax>ForceType <em>mime-type</em></syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<compatibility>Moved to the core in Apache 2.0</compatibility>

<usage>
    <p>When placed into an <code>.htaccess</code> file or a
    <directive type="section" module="core">Directory</directive>, or
    <directive type="section" module="core">Location</directive> or 
    <directive type="section" module="core">Files</directive>
    section, this directive forces all matching files to be served
    with the content type identification given by
    <em>mime-type</em>. For example, if you had a directory full of
    GIF files, but did not want to label them all with ".gif", you
    might want to use:</p>
<example>
    ForceType image/gif
</example>

    <p>Note that unlike <directive module="core">DefaultType</directive>,
    this directive overrides all mime-type associations, including
    filename extensions, that might identify the media type.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>HostnameLookups</name>
<description>Enables DNS lookups on client IP addresses</description>
<syntax>HostnameLookups on|off|double</syntax>
<default>HostnameLookups off</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context></contextlist>

<usage>
    <p>This directive enables DNS lookups so that host names can be
    logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
    The value <code>double</code> refers to doing double-reverse
    DNS. That is, after a reverse lookup is performed, a forward
    lookup is then performed on that result. At least one of the ip
    addresses in the forward lookup must match the original
    address. (In "tcpwrappers" terminology this is called
    <code>PARANOID</code>.)</p>

    <p>Regardless of the setting, when <module>mod_access</module> is
    used for controlling access by hostname, a double reverse lookup
    will be performed.  This is necessary for security. Note that the
    result of this double-reverse isn't generally available unless you
    set <code>HostnameLookups double</code>. For example, if only
    <code>HostnameLookups on</code> and a request is made to an object
    that is protected by hostname restrictions, regardless of whether
    the double-reverse fails or not, CGIs will still be passed the
    single-reverse result in <code>REMOTE_HOST</code>.</p>

    <p>The default is off in order to save the network
    traffic for those sites that don't truly need the reverse
    lookups done. It is also better for the end users because they
    don't have to suffer the extra latency that a lookup entails.
    Heavily loaded sites should leave this directive
    <code>off</code>, since DNS lookups can take considerable
    amounts of time. The utility <a
    href="../programs/logresolve.html">logresolve</a>, provided in
    the <em>/support</em> directory, can be used to look up host
    names from logged IP addresses offline.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>IdentityCheck</name>
<description>Enables logging of the RFC1413 identity of the remote 
user</description>
<syntax>IdentityCheck on|off</syntax>
<default>IdentityCheck off</default>

<usage>
    <p>This directive enables RFC1413-compliant logging of the
    remote user name for each connection, where the client machine
    runs identd or something similar. This information is logged in
    the access log.</p>

    <p>The information should not be trusted in any way except for
    rudimentary usage tracking.</p>

    <p>Note that this can cause serious latency problems accessing
    your server since every request requires one of these lookups
    to be performed. When firewalls are involved each lookup might
    possibly fail and add 30 seconds of latency to each hit. So in
    general this is not very useful on public servers accessible
    from the Internet.</p>
</usage>
</directivesynopsis>

<directivesynopsis type="section">
<name>IfDefine</name>
<description>Encloses directives that will be processed only
if a test is true at startup</description>
<syntax>&lt;IfDefine [!]<em>parameter-name</em>&gt; <em>...</em>
    &lt;/IfDefine&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>The <code>&lt;IfDefine
    <em>test</em>&gt;...&lt;/IfDefine&gt;</code> section is used to
    mark directives that are conditional. The directives within an
    <directive type="section">IfDefine</directive> section are only
    processed if the <em>test</em> is true. If <em>test</em> is false,
    everything between the start and end markers is ignored.</p>

    <p>The <em>test</em> in the <directive
    type="section">IfDefine</directive> section directive can be one
    of two forms:</p>

    <ul>
      <li><em>parameter-name</em></li>

      <li><code>!</code><em>parameter-name</em></li>
    </ul>

    <p>In the former case, the directives between the start and end
    markers are only processed if the parameter named
    <em>parameter-name</em> is defined. The second format reverses
    the test, and only processes the directives if
    <em>parameter-name</em> is <strong>not</strong> defined.</p>

    <p>The <em>parameter-name</em> argument is a define as given on
    the <code>httpd</code> command line via
    <code>-D</code><em>parameter-</em>, at the time the server was
    started.</p>

    <p><directive type="section">IfDefine</directive> sections are
    nest-able, which can be used to implement simple
    multiple-parameter tests. Example:</p>
<example><pre>
  $ httpd -DReverseProxy ...

  # httpd.conf
  &lt;IfDefine ReverseProxy&gt;
  LoadModule rewrite_module modules/mod_rewrite.so
  LoadModule proxy_module   modules/libproxy.so
  &lt;/IfDefine&gt;
</pre></example>

</usage>
</directivesynopsis>

<directivesynopsis type="section">
<name>IfModule</name>
<description>Encloses directives that are processed conditional on the
presence of absence of a specific module</description>
<syntax>&lt;IfModule [!]<em>module-name</em>&gt; <em>...</em>
    &lt;/IfModule&gt;</syntax>     
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>The <code>&lt;IfModule
    <em>test</em>&gt;...&lt;/IfModule&gt;</code> section is used to
    mark directives that are conditional. The directives within an
    <directive type="section">IfModule</directive> section are only
    processed if the <em>test</em> is true. If <em>test</em> is false,
    everything between the start and end markers is ignored.</p>

    <p>The <em>test</em> in the <directive
    type="section">IfModule</directive> section directive can be one
    of two forms:</p>

    <ul>
      <li><em>module name</em></li>

      <li>!<em>module name</em></li>
    </ul>

    <p>In the former case, the directives between the start and end
    markers are only processed if the module named <em>module
    name</em> is included in Apache -- either compiled in or
    dynamically loaded using <directive module="mod_so"
    >LoadModule</directive>. The second format
    reverses the test, and only processes the directives if <em>module
    name</em> is <strong>not</strong> included.</p>

    <p>The <em>module name</em> argument is the file name of the
    module, at the time it was compiled.
    For example, <code>mod_rewrite.c</code>.</p>

    <p><directive type="section">IfModule</directive> sections are
    nest-able, which can be used to implement simple multiple-module
    tests.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>Include</name>
<description>Includes other configuration files from within
the server configuration files</description>
<syntax>Include <em>file-path</em>|<em>directory-path</em></syntax>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>This directive allows inclusion of other configuration files
    from within the server configuration files.</p>

    <p>If <directive>Include</directive> points to a directory, rather than a
    file, Apache will read all files in that directory, and any
    subdirectory, and parse those as configuration files.</p>

    <p>The file path specified may be a fully qualified path (i.e.
    starting with a slash), or may be relative to the 
    <directive module="core">ServerRoot</directive> directory.</p>

    <p>Examples:</p>

<example>
     Include /usr/local/apache/conf/ssl.conf<br />
     Include /usr/local/apache/conf/vhosts/
</example>

     <p>Or, providing paths relative to your <code>ServerRoot</code>
     directory:</p>

<example>
     Include conf/ssl.conf<br />
     Include conf/vhosts/
</example>

     <p>Make sure that an included directory does not contain any stray
     files, such as editor temporary files, for example, as Apache will
     attempt to read them in and use the contents as configuration
     directives, which may cause the server to fail on start up.
     Running <code>apachectl configtest</code> will give you a list of
     the files that are being processed during the configuration
     check:</p>

<example><pre>
 root@host# apachectl configtest
  Processing config directory: /usr/local/apache/conf/vhosts
  Processing config file: /usr/local/apache/conf/vhosts/vhost1
  Processing config file: /usr/local/apache/conf/vhosts/vhost2
 Syntax OK
</pre></example>

     <p>This will help in verifying that you are getting only the files
     that you intended as part of your configuration.</p>
</usage>

<seealso><a href="../programs/apachectl.html">apachectl</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>KeepAlive</name>
<description>Turns on or off HTTP persistent connections.</description>
<syntax>KeepAlive on|off</syntax>
<default>KeepAlive On</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>The Keep-Alive extension to HTTP/1.0 and the persistent
    connection feature of HTTP/1.1 provide long-lived HTTP sessions
    which allow multiple requests to be sent over the same TCP
    connection. In some cases this has been shown to result in an
    almost 50% speedup in latency times for HTML documents with
    many images. To enable Keep-Alive connections in Apache 1.2 and
    later, set <code>KeepAlive On</code>.</p>

    <p>For HTTP/1.0 clients, Keep-Alive connections will only be
    used if they are specifically requested by a client. In
    addition, a Keep-Alive connection with an HTTP/1.0 client can
    only be used when the length of the content is known in
    advance. This implies that dynamic content such as CGI output,
    SSI pages, and server-generated directory listings will
    generally not use Keep-Alive connections to HTTP/1.0 clients.
    For HTTP/1.1 clients, persistent connections are the default
    unless otherwise specified. If the client requests it, chunked
    encoding will be used in order to send content of unknown
    length over persistent connections.</p>
</usage>

<seealso><directive module="core">MaxKeepAliveRequests</directive></seealso>
</directivesynopsis>

<directivesynopsis>
<name>KeepAliveTimeout</name>
<description>Sets the amount of time the server will wait for subsequent
requests on a persistent connection</description>
<syntax>KeepAliveTimeout <em>seconds</em></syntax>
<default>KeepAliveTimeout 15</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>The number of seconds Apache will wait for a subsequent
    request before closing the connection. Once a request has been
    received, the timeout value specified by the
    <directive module="core">Timeout</directive> directive applies.</p>

    <p>Setting <directive>KeepAliveTimeout</directive> to a high value
    may cause performance problems in heavily loaded servers. The
    higher the timeout, the more server processes will be kept
    occupied waiting on connections with idle clients.</p>
</usage>
</directivesynopsis>

<directivesynopsis type="section">
<name>Limit</name>
<description>Restrict access controls to only certain HTTP
methods</description>    
<syntax>&lt;Limit <em>method</em> [<em>method</em>] ... &gt; ...
    &lt;/Limit&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>Access controls are normally effective for
    <strong>all</strong> access methods, and this is the usual
    desired behavior. <strong>In the general case, access control
    directives should not be placed within a
    <directive type="section">limit</directive> section.</strong></p>

    <p>The purpose of the <directive type="section">Limit</directive>
    directive is to restrict the effect of the access controls to the
    nominated HTTP methods. For all other methods, the access
    restrictions that are enclosed in the <code>&lt;Limit&gt;</code>
    bracket <strong>will have no effect</strong>. The following
    example applies the access control only to the methods POST, PUT,
    and DELETE, leaving all other methods unprotected:</p>

<example>
      <code>&lt;Limit POST PUT DELETE&gt;<br />
       &nbsp;&nbsp;Require valid-user<br />
       &lt;/Limit&gt;</code>
</example>
    <p>The method names listed can be one or more of: GET, POST, PUT,
    DELETE, CONNECT, OPTIONS, TRACE, PATCH, PROPFIND, PROPPATCH,
    MKCOL, COPY, MOVE, LOCK, and UNLOCK. <strong>The method name is
    case-sensitive.</strong> If GET is used it will also restrict
    HEAD requests.</p>
</usage>
</directivesynopsis>

<directivesynopsis type="section">
<name>LimitExcept</name>
<description>Restrict access controls to all HTTP methods
except the named ones</description>    
<syntax>&lt;LimitExcept <em>method</em> [<em>method</em>] ... &gt; ...
    &lt;/LimitExcept&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p><directive type="section">LimitExcept</directive> and
    <code>&lt;/LimitExcept&gt;</code> are used to enclose a group of
    access control directives which will then apply to any HTTP access
    method <strong>not</strong> listed in the arguments; i.e., it is
    the opposite of a <directive type="section"
    module="core">Limit</directive> section and can be used to control
    both standard and nonstandard/unrecognized methods. See the
    documentation for <directive module="core"
    type="section">Limit</directive> for more details.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LimitRequestBody</name>
<description>Restricts the total size of the HTTP request body sent
from the client</description>
<syntax>LimitRequestBody <em>bytes</em></syntax>
<default>LimitRequestBody 0</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>This directive specifies the number of <em>bytes</em> from 0
    (meaning unlimited) to 2147483647 (2GB) that are allowed in a
    request body. The default value is defined by the compile-time
    constant <code>DEFAULT_LIMIT_REQUEST_BODY</code> (0 as
    distributed).</p>

    <p>The <directive>LimitRequestBody</directive> directive allows
    the user to set a limit on the allowed size of an HTTP request
    message body within the context in which the directive is given
    (server, per-directory, per-file or per-location). If the client
    request exceeds that limit, the server will return an error
    response instead of servicing the request. The size of a normal
    request message body will vary greatly depending on the nature of
    the resource and the methods allowed on that resource. CGI scripts
    typically use the message body for passing form information to the
    server. Implementations of the PUT method will require a value at
    least as large as any representation that the server wishes to
    accept for that resource.</p>

    <p>This directive gives the server administrator greater
    control over abnormal client request behavior, which may be
    useful for avoiding some forms of denial-of-service
    attacks.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LimitRequestFields</name>
<description>Limits the number of HTTP request header fields that 
will be accepted from the client</description>
<syntax>LimitRequestFields <em>number</em></syntax>
<default>LimitRequestFields 100</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p><em>Number</em> is an integer from 0 (meaning unlimited) to
    32767. The default value is defined by the compile-time
    constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
    distributed).</p>

    <p>The <directive>LimitRequestFields</directive> directive allows
    the server administrator to modify the limit on the number of
    request header fields allowed in an HTTP request. A server needs
    this value to be larger than the number of fields that a normal
    client request might include. The number of request header fields
    used by a client rarely exceeds 20, but this may vary among
    different client implementations, often depending upon the extent
    to which a user has configured their browser to support detailed
    content negotiation. Optional HTTP extensions are often expressed
    using request header fields.</p>

    <p>This directive gives the server administrator greater
    control over abnormal client request behavior, which may be
    useful for avoiding some forms of denial-of-service attacks.
    The value should be increased if normal clients see an error
    response from the server that indicates too many fields were
    sent in the request.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LimitRequestFieldSize</name>
<description>Limits the size of the HTTP request header allowed from the
client</description>
<syntax>LimitRequestFieldsize <em>bytes</em></syntax>
<default>LimitRequestFieldsize 8190</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>This directive specifies the number of <em>bytes</em> from 0
    to the value of the compile-time constant
    <code>DEFAULT_LIMIT_REQUEST_FIELDSIZE</code> (8190 as
    distributed) that will be allowed in an HTTP request
    header.</p>

    <p>The <directive>LimitRequestFieldsize</directive> directive
    allows the server administrator to reduce the limit on the allowed
    size of an HTTP request header field below the normal input buffer
    size compiled with the server. A server needs this value to be
    large enough to hold any one header field from a normal client
    request. The size of a normal request header field will vary
    greatly among different client implementations, often depending
    upon the extent to which a user has configured their browser to
    support detailed content negotiation.</p>

    <p>This directive gives the server administrator greater
    control over abnormal client request behavior, which may be
    useful for avoiding some forms of denial-of-service attacks.
    Under normal conditions, the value should not be changed from
    the default.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LimitRequestLine</name>
<description>Limit the size of the HTTP request line that will be accepted
from the client</description>
<syntax>LimitRequestLine <em>bytes</em></syntax>
<default>LimitRequestLine 8190</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>This directive sets the number of <em>bytes</em> from 0 to
    the value of the compile-time constant
    <code>DEFAULT_LIMIT_REQUEST_LINE</code> (8190 as distributed)
    that will be allowed on the HTTP request-line.</p>

    <p>The <directive>LimitRequestLine</directive> directive allows
    the server administrator to reduce the limit on the allowed size
    of a client's HTTP request-line below the normal input buffer size
    compiled with the server. Since the request-line consists of the
    HTTP method, URI, and protocol version, the
    <directive>LimitRequestLine</directive> directive places a
    restriction on the length of a request-URI allowed for a request
    on the server. A server needs this value to be large enough to
    hold any of its resource names, including any information that
    might be passed in the query part of a GET request.</p>

    <p>This directive gives the server administrator greater
    control over abnormal client request behavior, which may be
    useful for avoiding some forms of denial-of-service attacks.
    Under normal conditions, the value should not be changed from
    the default.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LimitXMLRequestBody</name>
<description>Limits the size of an XML-based request body</description>
<syntax>LimitXMLRequestBody <em>number</em></syntax>
<default>LimitXMLRequestBody 1000000</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>Limit (in bytes) on maximum size of an XML-based request
    body. A value of <code>0</code> will disable any checking.</p>
</usage>
</directivesynopsis>

<directivesynopsis type="section">
<name>Location</name>
<description>Applies the enclosed directives only to matching
URLs</description>
<syntax>&lt;Location
    <em>URL-path</em>|<em>URL</em>&gt; ... &lt;/Location&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive type="section">Location</directive> directive
    provides for access control by URL. It is similar to the
    <directive type="section" module="core">Directory</directive>
    directive, and starts a subsection which is terminated with a
    <code>&lt;/Location&gt;</code> directive. <directive
    type="section">Location</directive> sections are processed in the
    order they appear in the configuration file, after the <directive
    type="section" module="core">Directory</directive> sections and
    <code>.htaccess</code> files are read, and after the <directive
    type="section" module="core">Files</directive> sections.</p>

    <p>Note that URLs do not have to line up with the filesystem at
    all, it should be emphasized that &lt;Location&gt; operates
    completely outside the filesystem.</p>

    <p>For all origin (non-proxy) requests, the URL to be matched
    is of the form <code>/path/</code>, and you should not include
    any <code>http://servername</code> prefix. For proxy requests,
    the URL to be matched is of the form
    <code>scheme://servername/path</code>, and you must include the
    prefix.</p>

    <p>The URL may use wildcards In a wild-card string, `?' matches
    any single character, and `*' matches any sequences of
    characters.</p>

    <p>Extended regular
    expressions can also be used, with the addition of the
    <code>~</code> character. For example:</p>
<example>
   &lt;Location ~ "/(extra|special)/data"&gt;
</example>

    <p>would match URLs that contained the substring "/extra/data" or
    "/special/data". In Apache 1.3 and above, a new directive
    <directive type="section" module="core">LocationMatch</directive>
    exists which behaves identical to the regex version of
    <directive type="section">Location</directive>.</p>

    <p>The <directive type="section">Location</directive>
    functionality is especially useful when combined with the
    <directive module="core">SetHandler</directive>
    directive. For example, to enable status requests, but allow them
    only from browsers at foo.com, you might use:</p>
<example>
    &lt;Location /status&gt;<br />
    SetHandler server-status<br />
    Order Deny,Allow<br />
    Deny from all<br />
    Allow from .foo.com<br />
    &lt;/Location&gt;
</example>

<note><title>Note about / (slash)</title> <p>The slash character has
special meaning depending on where in a URL it appears. People may be
used to its behavior in the filesystem where multiple adjacent slashes
are frequently collapsed to a single slash (<em>i.e.</em>,
<code>/home///foo</code> is the same as <code>/home/foo</code>). In
URL-space this is not necessarily true. The <directive type="section"
module="core">LocationMatch</directive> directive and the regex
version of <directive type="section">Location</directive> require you
to explicitly specify multiple slashes if that is your intention.  For
example, <code>&lt;LocationMatch ^/abc&gt;</code> would match the
request URL <code>/abc</code> but not the request URL
<code>//abc</code>. The (non-regex) <directive
type="section">Location</directive> directive behaves similarly when
used for proxy requests. But when (non-regex) <directive
type="section">Location</directive> is used for non-proxy requests it
will implicitly match multiple slashes with a single slash. For
example, if you specify <code>&lt;Location /abc/def&gt;</code> and the
request is to <code>/abc//def</code> then it will match.</p>
</note>
</usage>
<seealso><a href="../sections.html">How
    Directory, Location and Files sections work</a> for an
    explanation of how these different sections are combined when a
    request is received</seealso>
</directivesynopsis>

<directivesynopsis type="section">
<name>LocationMatch</name>
<description>Applies the enclosed directives only to regular-expression 
matching URLs</description>
<syntax>&lt;LocationMatch
    <em>regex</em>&gt; ... &lt;/Location&gt;</syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive type="section">LocationMatch</directive> directive
    provides for access control by URL, in an identical manner to
    <directive module="core"
    type="section">Location</directive>. However, it takes a regular
    expression as an argument instead of a simple string.  For
    example:</p>
<example>
   &lt;LocationMatch "/(extra|special)/data"&gt;
</example>

    <p>would match URLs that contained the substring "/extra/data"
    or "/special/data".</p>
</usage>

<seealso><a href="../sections.html">How
    Directory, Location and Files sections work</a> for an
    explanation of how these different sections are combined when a
    request is received</seealso>
</directivesynopsis>

<directivesynopsis>
<name>LogLevel</name>
<description>Controls the verbosity of the ErrorLog</description>
<syntax>LogLevel <em>level</em></syntax>
<default>LogLevel warn</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p><directive>LogLevel</directive> adjusts the verbosity of the
    messages recorded in the error logs (see <directive
    module="core">ErrorLog</directive> directive). The following
    <em>level</em>s are available, in order of decreasing
    significance:</p>

    <table>
      <tr>
        <th align="LEFT"><strong>Level</strong> </th>

        <th align="LEFT"><strong>Description</strong> </th>
      </tr>

      <tr>
        <th>
        </th>

        <th align="LEFT"><strong>Example</strong> </th>
      </tr>

      <tr>
        <td><code>emerg</code> </td>

        <td>Emergencies - system is unusable.</td>
      </tr>

      <tr>
        <td>
        </td>

        <td>"Child cannot open lock file. Exiting"</td>
      </tr>

      <tr>
        <td><code>alert</code> </td>

        <td>Action must be taken immediately.</td>
      </tr>

      <tr>
        <td>
        </td>

        <td>"getpwuid: couldn't determine user name from uid"</td>
      </tr>

      <tr>
        <td><code>crit</code> </td>

        <td>Critical Conditions.</td>
      </tr>

      <tr>
        <td>
        </td>

        <td>"socket: Failed to get a socket, exiting child"</td>
      </tr>

      <tr>
        <td><code>error</code> </td>

        <td>Error conditions.</td>
      </tr>

      <tr>
        <td>
        </td>

        <td>"Premature end of script headers"</td>
      </tr>

      <tr>
        <td><code>warn</code> </td>

        <td>Warning conditions.</td>
      </tr>

      <tr>
        <td>
        </td>

        <td>"child process 1234 did not exit, sending another
        SIGHUP"</td>
      </tr>

      <tr>
        <td><code>notice</code> </td>

        <td>Normal but significant condition.</td>
      </tr>

      <tr>
        <td>
        </td>

        <td>"httpd: caught SIGBUS, attempting to dump core in
        ..."</td>
      </tr>

      <tr>
        <td><code>info</code> </td>

        <td>Informational.</td>
      </tr>

      <tr>
        <td>
        </td>

        <td>"Server seems busy, (you may need to increase
        StartServers, or Min/MaxSpareServers)..."</td>
      </tr>

      <tr>
        <td><code>debug</code> </td>

        <td>Debug-level messages</td>
      </tr>

      <tr>
        <td>
        </td>

        <td>"Opening config file ..."</td>
      </tr>
    </table>

    <p>When a particular level is specified, messages from all
    other levels of higher significance will be reported as well.
    <em>E.g.</em>, when <code>LogLevel info</code> is specified,
    then messages with log levels of <code>notice</code> and
    <code>warn</code> will also be posted.</p>

    <p>Using a level of at least <code>crit</code> is
    recommended.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>MaxKeepAliveRequests</name>
<description>Sets the number of requests allowed on a persistent 
connection</description>
<syntax>MaxKeepAliveRequests <em>number</em></syntax>
<default>MaxKeepAliveRequests 100</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>The <directive>MaxKeepAliveRequests</directive> directive
    limits the number of requests allowed per connection when
    <directive module="core" >KeepAlive</directive> is on. If it is
    set to "<code>0</code>", unlimited requests will be allowed. We
    recommend that this setting be kept to a high value for maximum
    server performance.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>NameVirtualHost</name>
<description>Configures an IP address for name-virtual
hosting</description>
<syntax>NameVirtualHost <em>addr</em>[:<em>port</em>]</syntax>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>The <directive>NameVirtualHost</directive> directive is a
    required directive if you want to configure <a
    href="../vhosts/">name-based virtual hosts</a>.</p>

    <p>Although <em>addr</em> can be hostname it is recommended
    that you always use an IP address, <em>e.g.</em></p>

<example>NameVirtualHost 111.22.33.44</example>

    <p>With the <directive>NameVirtualHost</directive> directive you
    specify the IP address on which the server will receive requests
    for the name-based virtual hosts. This will usually be the address
    to which your name-based virtual host names resolve. In cases
    where a firewall or other proxy receives the requests and forwards
    them on a different IP address to the server, you must specify the
    IP address of the physical interface on the machine which will be
    servicing the requests. If you have multiple name-based hosts on
    multiple addresses, repeat the directive for each address.</p>

    <p>Note: the "main server" and any _default_ servers will
    <strong>never</strong> be served for a request to a
    <directive>NameVirtualHost</directive> IP Address (unless for some
    reason you specify <directive>NameVirtualHost</directive> but then
    don't define any VirtualHosts for that address).</p>

    <p>Optionally you can specify a port number on which the
    name-based virtual hosts should be used, <em>e.g.</em></p>

<example>NameVirtualHost 111.22.33.44:8080</example>

     <p>IPv6 addresses must be enclosed in square brackets, as shown
     in the following example:</p>
 
<example>NameVirtualHost [fe80::a00:20ff:fea7:ccea]:8080</example>

</usage>
</directivesynopsis>

<directivesynopsis>
<name>Options</name>
<description>Configures what features are available in a particular
directory</description>
<syntax>Options
    [+|-]<em>option</em> [[+|-]<em>option</em>] ...</syntax>
<default>Options All</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>Options</override>

<usage>
    <p>The <directive>Options</directive> directive controls which
    server features are available in a particular directory.</p>

    <p><em>option</em> can be set to <code>None</code>, in which
    case none of the extra features are enabled, or one or more of
    the following:</p>

    <dl>
      <dt>All</dt>

      <dd>All options except for MultiViews. This is the default
      setting.</dd>

      <dt>ExecCGI</dt>

      <dd>
      Execution of CGI scripts is permitted.</dd>

      <dt>FollowSymLinks</dt>

      <dd>

      The server will follow symbolic links in this directory.<br />
      <strong>Note</strong>: even though the server follows the
      symlink it does <em>not</em> change the pathname used to match
      against <directive type="section"
      module="core">Directory</directive> sections.<br />
      <strong>Note</strong>: this option gets ignored if set inside a
      <directive type="section" module="core">Location</directive>
      section.</dd>

      <dt>Includes</dt>

      <dd>
      Server-side includes are permitted.</dd>

      <dt>IncludesNOEXEC</dt>

      <dd>

      Server-side includes are permitted, but the #exec command and
      #exec CGI are disabled. It is still possible to #include
      virtual CGI scripts from ScriptAliase'd directories.</dd>

      <dt>Indexes</dt>

      <dd>
      If a URL which maps to a directory is requested, and the
      there is no DirectoryIndex (<em>e.g.</em>, index.html) in
      that directory, then the server will return a formatted
      listing of the directory.</dd>

      <dt>MultiViews</dt>

      <dd>
      <a href="../content-negotiation.html">Content negotiated</a>
      MultiViews are allowed.</dd>

      <dt>SymLinksIfOwnerMatch</dt>

      <dd>

      The server will only follow symbolic links for which the target
      file or directory is owned by the same user id as the link.<br
      /> <strong>Note</strong>: this option gets ignored if set inside
      a <directive module="core" type="section">Location</directive>
      section.</dd>
    </dl>
    <p>Normally, if multiple <directive>Options</directive> could apply to a
    directory, then the most specific one is taken complete; the
    options are not merged. However if <em>all</em> the options on
    the <directive>Options</directive> directive are preceded by a + or -
    symbol, the options are merged. Any options preceded by a + are
    added to the options currently in force, and any options
    preceded by a - are removed from the options currently in
    force. </p>

    <p>For example, without any + and - symbols:</p>


<example>&lt;Directory /web/docs&gt;<br />
       Options Indexes FollowSymLinks<br />
       &lt;/Directory&gt;<br />
       &lt;Directory /web/docs/spec&gt;<br />
       Options Includes<br />
       &lt;/Directory&gt;
</example>
    <p>then only <code>Includes</code> will be set for the
    /web/docs/spec directory. However if the second
    <directive>Options</directive> directive uses the + and - symbols:</p> 

<example>
      &lt;Directory /web/docs&gt;<br />
       Options Indexes FollowSymLinks<br />
       &lt;/Directory&gt;<br />
       &lt;Directory /web/docs/spec&gt;<br />
       Options +Includes -Indexes<br />
       &lt;/Directory&gt;
</example>
    <p>then the options <code>FollowSymLinks</code> and
    <code>Includes</code> are set for the /web/docs/spec directory.</p>
    

    <p><strong>Note:</strong> Using <code>-IncludesNOEXEC</code> or
    <code>-Includes</code> disables server-side includes completely
    regardless of the previous setting.</p>

    <p>The default in the absence of any other settings is
    <code>All</code>.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>Require</name>
<description>Selects which authenticated users can access
a resource</description>    
<syntax>Require <em>entity-name</em> [<em>entity-name</em>] ...</syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>This directive selects which authenticated users can access
    a directory. The allowed syntaxes are:</p>

    <ul>
      <li>
        Require user <em>userid</em> [<em>userid</em>] ... 

        <p>Only the named users can access the directory.</p>
      </li>

      <li>
        Require group <em>group-name</em> [<em>group-name</em>] ...
        

        <p>Only users in the named groups can access the
        directory.</p>
      </li>

      <li>
        Require valid-user 

        <p>All valid users can access the directory.</p>
      </li>
    </ul>

    <p><directive>Require</directive> must be accompanied by
    <directive module="core">AuthName</directive> and <directive
    module="core">AuthType</directive> directives, and directives such
    as <directive module="mod_auth">AuthUserFile</directive>
    and <directive module="mod_auth">AuthGroupFile</directive> (to
    define users and groups) in order to work correctly. Example:</p>

<example>
       AuthType Basic<br />
       AuthName "Restricted Directory"<br />
       AuthUserFile /web/users<br />
       AuthGroupFile /web/groups<br />
       Require group admin<br />
</example>

    <p>Access controls which are applied in this way are effective for
    <strong>all</strong> methods. <strong>This is what is normally
    desired.</strong> If you wish to apply access controls only to
    specific methods, while leaving other methods unprotected, then
    place the <directive>Require</directive> statement into a
    <directive module="core" type="section">Limit</directive>
    section.</p>
</usage>
<seealso><directive module="core">Satisfy</directive></seealso>
<seealso><module>mod_access</module></seealso>
</directivesynopsis>

<directivesynopsis>
<name>RLimitCPU</name>
<description>Limits the CPU consumption of processes launched
by Apache children</description>
<syntax>RLimitCPU <em>number</em>|max [<em>number</em>|max]</syntax>
<default>Unset; uses operating system defaults</default>
<contextlist>><context>server config</context><context>virtual host</context>
</contextlist>
<compatibility>Moved in version 2.0 to
    the <a href="../mpm.html">MPMs</a></compatibility>

<usage>
    <p>Takes 1 or 2 parameters. The first parameter sets the soft
    resource limit for all processes and the second parameter sets
    the maximum resource limit. Either parameter can be a number,
    or <em>max</em> to indicate to the server that the limit should
    be set to the maximum allowed by the operating system
    configuration. Raising the maximum resource limit requires that
    the server is running as root, or in the initial startup
    phase.</p>

    <p>This applies to processes forked off from Apache children
    servicing requests, not the Apache children themselves. This
    includes CGI scripts and SSI exec commands, but not any
    processes forked off from the Apache parent such as piped
    logs.</p>

    <p>CPU resource limits are expressed in seconds per
    process.</p>
</usage>
<seealso><directive module="core">RLimitMEM</directive></seealso>
<seealso><directive module="core">RLimitNPROC</directive></seealso>
</directivesynopsis>

<directivesynopsis>
<name>RLimitMEM</name>
<description>Limits the memory consumption of processes launched
by Apache children</description>
<syntax>RLimitMEM <em>number</em>|max [<em>number</em>|max]</syntax>
<default>Unset; uses operating system defaults</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>
<compatibility>Moved in version 2.0 to the <a
href="../mpm.html">MPMs</a>.</compatibility>

<usage>
    <p>Takes 1 or 2 parameters. The first parameter sets the soft
    resource limit for all processes and the second parameter sets
    the maximum resource limit. Either parameter can be a number,
    or <em>max</em> to indicate to the server that the limit should
    be set to the maximum allowed by the operating system
    configuration. Raising the maximum resource limit requires that
    the server is running as root, or in the initial startup
    phase.</p>

    <p>This applies to processes forked off from Apache children
    servicing requests, not the Apache children themselves. This
    includes CGI scripts and SSI exec commands, but not any
    processes forked off from the Apache parent such as piped
    logs.</p>

    <p>Memory resource limits are expressed in bytes per
    process.</p>
</usage>
<seealso><directive module="core">RLimitCPU</directive></seealso>
<seealso><directive module="core">RLimitNPROC</directive></seealso>
</directivesynopsis>

<directivesynopsis>
<name>RLimitNPROC</name>
<description>Limits the number of processes that can be launched by 
processes launched by Apache children</description>
<syntax>RLimitNPROC <em>number</em>|max [<em>number</em>|max]</syntax>
<default>Unset; uses operating system defaults</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>
<compatibility>Moved in version 2.0 to the <a
href="../mpm.html">MPMs</a>.</compatibility>

<usage>
    <p>Takes 1 or 2 parameters. The first parameter sets the soft
    resource limit for all processes and the second parameter sets
    the maximum resource limit. Either parameter can be a number,
    or <code>max</code> to indicate to the server that the limit
    should be set to the maximum allowed by the operating system
    configuration. Raising the maximum resource limit requires that
    the server is running as root, or in the initial startup
    phase.</p>

    <p>This applies to processes forked off from Apache children
    servicing requests, not the Apache children themselves. This
    includes CGI scripts and SSI exec commands, but not any
    processes forked off from the Apache parent such as piped
    logs.</p>

    <p>Process limits control the number of processes per user.</p>

    <p>Note: If CGI processes are <strong>not</strong> running
    under userids other than the web server userid, this directive
    will limit the number of processes that the server itself can
    create. Evidence of this situation will be indicated by
    <strong><em>cannot fork</em></strong> messages in the
    error_log.</p>
</usage>
<seealso><directive module="core">RLimitMEM</directive></seealso>
<seealso><directive module="core">RLimitCPU</directive></seealso>
</directivesynopsis>

<directivesynopsis>
<name>Satisfy</name>
<description>Configures how host-level access control and user authentication
interact</description>
<syntax>Satisfy any|all</syntax>
<default>Satisfy all</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>Access policy if both <directive
    module="core">Allow</directive> and <directive
    module="core">Require</directive> used. The parameter can be
    either <em>'all'</em> or <em>'any'</em>. This directive is only
    useful if access to a particular area is being restricted by both
    username/password <em>and</em> client host address. In this case
    the default behavior ("all") is to require that the client passes
    the address access restriction <em>and</em> enters a valid
    username and password. With the "any" option the client will be
    granted access if they either pass the host restriction or enter a
    valid username and password. This can be used to password restrict
    an area, but to let clients from particular addresses in without
    prompting for a password.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>ScriptInterpreterSource</name>
<description>Controls how the interpreter for CGI scripts is
located</description>
<syntax>ScriptInterpreterSource registry|script</syntax>
<default>ScriptInterpreterSource script</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<compatibility>Win32 only</compatibility>

<usage>
    <p>This directive is used to control how Apache finds the
    interpreter used to run CGI scripts. The default technique is to
    use the interpreter pointed to by the #! line in the
    script. Setting <code>ScriptInterpreterSource registry</code> will
    cause the Windows Registry to be searched using the script file
    extension (e.g., .pl) as a search key.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>ServerAdmin</name>
<description>Sets the email address that the server includes in error
messages sent to the client</description>
<syntax>ServerAdmin <em>email-address</em></syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>ServerAdmin</directive> sets the e-mail address
    that the server includes in any error messages it returns to the
    client.</p>

    <p>It may be worth setting up a dedicated address for this,
    <em>e.g.</em></p>
<example>ServerAdmin www-admin@foo.bar.com</example>
    <p>as users do not always mention that they are talking about the
    server!</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>ServerAlias</name>
<description>Sets alternate names for a host used when matching requests
to name-virtual hosts</description>
<syntax>ServerAlias <em>hostname</em> [<em>hostname</em>] ...</syntax>
<contextlist><context>virtual host</context></contextlist>

<usage>
    <p>The <directive>ServerAlias</directive> directive sets the
    alternate names for a host, for use with <a
    href="../vhosts/name-based.html">name-based virtual hosts</a>.</p>

<example>
    &lt;VirtualHost *&gt;<br />
    ServerName server.domain.com<br />
    ServerAlias server server2.domain.com server2<br />
    ...<br />
    &lt;/VirtualHost&gt;
</example>
</usage>
<seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>ServerName</name>
<description>Sets the hostname and port that the server uses to identify
itself</description>
<syntax>ServerName <em>fully-qualified-domain-name[:port]</em></syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>
<compatibility>In version 2.0, this
     directive supersedes the functionality of the <directive>Port</directive>
     directive from version 1.3.</compatibility>

<usage>
    <p>The <directive>ServerName</directive> directive sets the hostname and
    port that the server uses to identify itself.  This is used when
    creating redirection URLs.  For example, if the name of the
    machine hosting the webserver is <code>simple.example.com</code>,
    but the machine also has the DNS alias <code>www.example.com</code>
    and you wish the webserver to be so identified, the following
    directive should be used:</p>

<example>ServerName www.example.com:80</example>

    <p>If no <directive>ServerName</directive> is specified, then the
    server attempts to deduce the hostname by performing a reverse
    lookup on the IP address.  If no port is specified in the
    servername, then the server will use the port from the incoming
    request.  For optimal reliability and predictability, you should
    specify an explicit hostname and port using the
    <directive>ServerName</directive> directive.</p>

    <p>If you are using <a
    href="../vhosts/name-based.html">name-based virtual hosts</a>,
    the <directive>ServerName</directive> inside a
    <directive type="section" module="core">VirtualHost</directive>
    section specifies what hostname must appear in the request's
    <code>Host:</code> header to match this virtual host.</p>

    <p>See the description of the
    <directive module="core">UseCanonicalName</directive> directive for
    settings which determine whether self-referential URL's (e.g., by the
    <module>mod_dir</module> module) will refer to the
    specified port, or to the port number given in the client's request.
    </p>
</usage>

<seealso><a href="../dns-caveats.html">DNS Issues</a></seealso>
<seealso><a href="../vhosts/">Apache virtual host
    documentation</a></seealso>
<seealso><directive module="core">UseCanonicalName</directive></seealso>
<seealso><directive module="core">NameVirtualHost</directive></seealso>
<seealso><directive module="core">ServerAlias</directive></seealso>
</directivesynopsis>

<directivesynopsis>
<name>ServerPath</name>
<description>Sets the legacy URL pathname for a name-virtual host that
is accessed by an incompatible browser</description>
<syntax>ServerPath <em>directory-path</em></syntax>
<contextlist><context>virtual host</context></contextlist>

<usage>
    <p>The <directive>ServerPath</directive> directive sets the legacy
    URL pathname for a host, for use with <a
    href="../vhosts/">name-based virtual hosts</a>.</p>
</usage>
<seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
</directivesynopsis>

<directivesynopsis>
<name>ServerRoot</name>
<description>Sets the base directory for the server installation</description>
<syntax>ServerRoot <em>directory-path</em></syntax>
<default>ServerRoot /usr/local/apache</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>The <directive>ServerRoot</directive> directive sets the
    directory in which the server lives. Typically it will contain the
    subdirectories <code>conf/</code> and <code>logs/</code>. Relative
    paths for other configuration files are taken as relative to this
    directory.</p>
</usage>
<seealso><a href="../invoking.html">the <code>-d</code>
    option to <code>httpd</code></a></seealso>
<seealso><a href="../misc/security_tips.html#serverroot">the
    security tips</a> for information on how to properly set
    permissions on the ServerRoot</seealso>
</directivesynopsis>

<directivesynopsis>
<name>ServerSignature</name>
<description>Configures the footer on server-generated documents</description>
<syntax>ServerSignature On|Off|EMail</syntax>
<default>ServerSignature Off</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>The <directive>ServerSignature</directive> directive allows the
    configuration of a trailing footer line under server-generated
    documents (error messages, mod_proxy ftp directory listings,
    mod_info output, ...). The reason why you would want to enable
    such a footer line is that in a chain of proxies, the user often
    has no possibility to tell which of the chained servers actually
    produced a returned error message.<br /> The <samp>Off</samp>
    setting, which is the default, suppresses the error line (and is
    therefore compatible with the behavior of Apache-1.2 and
    below). The <samp>On</samp> setting simply adds a line with the
    server version number and <directive
    module="core">ServerName</directive> of the serving virtual host,
    and the <samp>EMail</samp> setting additionally creates a
    "mailto:" reference to the <directive
    module="core">ServerAdmin</directive> of the referenced
    document.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>ServerTokens</name>
<description>Configures the Server HTTP response header</description>
<syntax>ServerTokens Minimal|ProductOnly|OS|Full</syntax>
<default>ServerTokens Full</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>This directive controls whether <samp>Server</samp> response
    header field which is sent back to clients includes a
    description of the generic OS-type of the server as well as
    information about compiled-in modules.</p>

    <dl>
      <dt><code>ServerTokens Prod[uctOnly]</code></dt>

      <dd>Server sends (<em>e.g.</em>): <samp>Server:
      Apache</samp></dd>

      <dt><code>ServerTokens Min[imal]</code></dt>

      <dd>Server sends (<em>e.g.</em>): <samp>Server:
      Apache/1.3.0</samp></dd>

      <dt><code>ServerTokens OS</code></dt>

      <dd>Server sends (<em>e.g.</em>): <samp>Server: Apache/1.3.0
      (Unix)</samp></dd>

      <dt><code>ServerTokens Full</code> (or not specified)</dt>

      <dd>Server sends (<em>e.g.</em>): <samp>Server: Apache/1.3.0
      (Unix) PHP/3.0 MyMod/1.2</samp></dd>
    </dl>

    <p>This setting applies to the entire server, and cannot be
    enabled or disabled on a virtualhost-by-virtualhost basis.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>SetHandler</name>
<description>Forces all matching files to be processed by a
handler</description>
<syntax>SetHandler <em>handler-name</em></syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<compatibility>Moved into the core in Apache 2.0</compatibility>

<usage>
    <p>When placed into an <code>.htaccess</code> file or a
    <directive type="section" module="core">Directory</directive> or 
    <directive type="section" module="core">Location</directive>
    section, this directive forces all matching files to be parsed
    through the <a href="../handler.html">handler</a> given by
    <em>handler-name</em>. For example, if you had a directory you
    wanted to be parsed entirely as imagemap rule files, regardless
    of extension, you might put the following into an
    <code>.htaccess</code> file in that directory:</p>
<example>
    SetHandler imap-file
</example>

    <p>Another example: if you wanted to have the server display a
    status report whenever a URL of
    <code>http://servername/status</code> was called, you might put
    the following into httpd.conf:</p>
<example>
    &lt;Location /status&gt;<br />
    SetHandler server-status<br />
    &lt;/Location&gt;
</example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>SetInputFilter</name>
<description>Sets the filters that will process client requests and POST
input</description>
<syntax>SetInputFilter <em>filter</em>[<em>;filter</em>...]</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>The <directive>SetInputFilter</directive> directive sets the
    filter or filters which will process client requests and POST
    input when they are received by the server. This is in addition to
    any filters defined elsewhere, including the
    <directive module="mod_mime">AddInputFilter</directive>
    directive.</p>

    <p>If more than one filter is specified, they must be separated
    by semicolons in the order in which they should process the
    content.</p>
</usage>
<seealso><a href="../filter.html">Filters</a> documentation</seealso>
</directivesynopsis>

<directivesynopsis>
<name>SetOutputFilter</name>
<description>Sets the filters that will process responses from the
server</description>
<syntax>SetOutputFilter <em>filter</em> [<em>filter</em>] ...</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>

<usage>
    <p>The <directive>SetOutputFilter</directive> directive sets the filters
    which will process responses from the server before they are
    sent to the client. This is in addition to any filters defined
    elsewhere, including the
    <directive module="mod_mime">AddOutputFilter</directive>
    directive.</p>

    <p>For example, the following configuration will process all files
    in the <code>/www/data/</code> directory for server-side
    includes.</p>
<example>
&lt;Directory /www/data/&gt;<br />
&nbsp;&nbsp;SetOutputFilter INCLUDES<br />
&lt;/Directory&gt;
</example>

    <p>If more than one filter is specified, they must be separated
    by semicolons in the order in which they should process the
    content.</p>
</usage>
<seealso><a href="../filter.html">Filters</a> documentation</seealso>
</directivesynopsis>

<directivesynopsis>
<name>TimeOut</name>
<description>Defines the amount of time the server will wait for
certain events before failing a request</description>
<syntax>TimeOut <em>number</em></syntax>
<default>TimeOut 300</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>The <directive>TimeOut</directive> directive currently defines
    the amount of time Apache will wait for three things:</p>

    <ol>
      <li>The total amount of time it takes to receive a GET
      request.</li>

      <li>The amount of time between receipt of TCP packets on a
      POST or PUT request.</li>

      <li>The amount of time between ACKs on transmissions of TCP
      packets in responses.</li>
    </ol>
    
    <p>We plan on making these separately configurable at some point
    down the road. The timer used to default to 1200 before 1.2,
    but has been lowered to 300 which is still far more than
    necessary in most situations. It is not set any lower by
    default because there may still be odd places in the code where
    the timer is not reset when a packet is sent. </p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>UseCanonicalName</name>
<description>Configures how the server determines its own name and
port</description>
<syntax>UseCanonicalName on|off|dns</syntax>
<default>UseCanonicalName on</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context></contextlist>
<override>Options</override>

<usage>
    <p>In many situations Apache has to construct a
    <em>self-referential</em> URL. That is, a URL which refers back to
    the same server. With <code>UseCanonicalName on</code> Apache will
    use the hostname and port specified in the <directive
    module="core">ServerName</directive> directive to construct a canonical
    name for the server. This name is used in all self-referential
    URLs, and for the values of <code>SERVER_NAME</code> and
    <code>SERVER_PORT</code> in CGIs.</p>

    <p>With <code>UseCanonicalName off</code> Apache will form
    self-referential URLs using the hostname and port supplied by
    the client if any are supplied (otherwise it will use the
    canonical name). These values are the same that are used to
    implement <a href="../vhosts/name-based.html">name based
    virtual hosts</a>, and are available with the same clients. The
    CGI variables <code>SERVER_NAME</code> and
    <code>SERVER_PORT</code> will be constructed from the client
    supplied values as well.</p>

    <p>An example where this may be useful is on an intranet server
    where you have users connecting to the machine using short
    names such as <code>www</code>. You'll notice that if the users
    type a shortname, and a URL which is a directory, such as
    <code>http://www/splat</code>, <em>without the trailing
    slash</em> then Apache will redirect them to
    <code>http://www.domain.com/splat/</code>. If you have
    authentication enabled, this will cause the user to have to
    reauthenticate twice (once for <code>www</code> and once again
    for <code>www.domain.com</code>). But if
    <directive>UseCanonicalName</directive> is set off, then Apache will
    redirect to <code>http://www/splat/</code>.</p>

    <p>There is a third option, <code>UseCanonicalName DNS</code>,
    which is intended for use with mass IP-based virtual hosting to
    support ancient clients that do not provide a
    <code>Host:</code> header. With this option Apache does a
    reverse DNS lookup on the server IP address that the client
    connected to in order to work out self-referential URLs.</p>

    <p><strong>Warning:</strong> if CGIs make assumptions about the
    values of <code>SERVER_NAME</code> they may be broken by this
    option. The client is essentially free to give whatever value
    they want as a hostname. But if the CGI is only using
    <code>SERVER_NAME</code> to construct self-referential URLs
    then it should be just fine.</p>
</usage>
<seealso><directive module="core">ServerName</directive></seealso>
<seealso><directive module="mpm_common">Listen</directive></seealso>
</directivesynopsis>

<directivesynopsis type="section">
<name>VirtualHost</name>
<description>Contains directives that apply only to a specific
hostname or IP address</description>    
<syntax>&lt;VirtualHost
    <em>addr</em>[:<em>port</em>] [<em>addr</em>[:<em>port</em>]]
    ...&gt; ... &lt;/VirtualHost&gt;</syntax>
<contextlist><context>server config</context></contextlist>

<usage>
    <p><directive type="section">VirtualHost</directive> and
    <code>&lt;/VirtualHost&gt;</code> are used to enclose a group of
    directives which will apply only to a particular virtual host. Any
    directive which is allowed in a virtual host context may be
    used. When the server receives a request for a document on a
    particular virtual host, it uses the configuration directives
    enclosed in the <directive type="section">VirtualHost</directive>
    section. <em>Addr</em> can be</p>

    <ul>
      <li>The IP address of the virtual host</li>

      <li>A fully qualified domain name for the IP address of the
      virtual host.</li>
    </ul>
    Example: 

<example>&lt;VirtualHost 10.1.2.3&gt;<br />
       ServerAdmin webmaster@host.foo.com<br />
       DocumentRoot /www/docs/host.foo.com<br />
       ServerName host.foo.com<br />
       ErrorLog logs/host.foo.com-error_log<br />
       TransferLog logs/host.foo.com-access_log<br />
       &lt;/VirtualHost&gt;
</example>

 
     <p>IPv6 addresses must be specified in square brackets because
     the optional port number could not be determined otherwise.  An
     IPv6 example is shown below:</p>

<example>     
&lt;VirtualHost [fe80::a00:20ff:fea7:ccea]&gt;<br />
        ServerAdmin webmaster@host.foo.com<br />
        DocumentRoot /www/docs/host.foo.com<br />
        ServerName host.foo.com<br />
       ErrorLog logs/host.foo.com-error_log<br />
        TransferLog logs/host.foo.com-access_log<br />
        &lt;/VirtualHost&gt;
</example>  

    <p>Each Virtual Host must correspond to a different IP address,
    different port number or a different host name for the server,
    in the former case the server machine must be configured to
    accept IP packets for multiple addresses. (If the machine does
    not have multiple network interfaces, then this can be
    accomplished with the <code>ifconfig alias</code> command (if
    your OS supports it), or with kernel patches like <a
    href="../misc/vif-info.html">VIF</a> (for SunOS(TM) 4.1.x)).</p>

    <p>The special name <code>_default_</code> can be specified in
    which case this virtual host will match any IP address that is
    not explicitly listed in another virtual host. In the absence
    of any _default_ virtual host the "main" server config,
    consisting of all those definitions outside any VirtualHost
    section, is used when no match occurs.</p>

    <p>You can specify a <code>:port</code> to change the port that is
    matched. If unspecified then it defaults to the same port as the
    most recent <directive module="mpm_common">Listen</directive>
    statement of the main server. You may also specify <code>:*</code>
    to match all ports on that address. (This is recommended when used
    with <code>_default_</code>.)</p>

    <p><strong>SECURITY</strong>: See the <a
    href="../misc/security_tips.html">security tips</a> document
    for details on why your security could be compromised if the
    directory where logfiles are stored is writable by anyone other
    than the user that starts the server.</p>

    <p><strong>NOTE</strong>: The use of <directive
    type="section">VirtualHost</directive> does <strong>not</strong>
    affect what addresses Apache listens on.  You may need to ensure
    that Apache is listening on the correct addresses using <directive
    module="mpm_common">Listen</directive>.</p>
</usage>
<seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
<seealso><a href="../dns-caveats.html">Warnings about DNS and
    Apache</a></seealso>
<seealso><a href="../bind.html">Setting
    which addresses and ports Apache uses</a></seealso>
<seealso><a href="../sections.html">How
    Directory, Location and Files sections work</a> for an
    explanation of how these different sections are combined when a
    request is received</seealso>
</directivesynopsis>

</modulesynopsis>