mirror of
https://github.com/apache/httpd.git
synced 2025-04-18 22:24:07 +03:00
fd179953f4
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1917054 13f79535-47bb-0310-9956-ffa450edef68
537 lines
31 KiB
XML
537 lines
31 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
|
|
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
|
|
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" />
|
|
<!--
|
|
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
|
|
This file is generated from xml source: DO NOT EDIT
|
|
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
|
|
-->
|
|
<title>Environment Variables in Apache - Apache HTTP Server Version 2.5</title>
|
|
<link href="./style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
|
|
<link href="./style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
|
|
<link href="./style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="./style/css/prettify.css" />
|
|
<script src="./style/scripts/prettify.min.js" type="text/javascript">
|
|
</script>
|
|
|
|
<link href="./images/favicon.ico" rel="shortcut icon" /></head>
|
|
<body id="manual-page"><div id="page-header">
|
|
<p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p>
|
|
<p class="apache">Apache HTTP Server Version 2.5</p>
|
|
<img alt="" src="./images/feather.png" /></div>
|
|
<div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div>
|
|
<div id="path">
|
|
<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.5</a></div><div id="page-content"><div id="preamble"><h1>Environment Variables in Apache</h1>
|
|
<div class="toplang">
|
|
<p><span>Available Languages: </span><a href="./en/env.html" title="English"> en </a> |
|
|
<a href="./fr/env.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
|
|
<a href="./ja/env.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
|
|
<a href="./ko/env.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
|
|
<a href="./tr/env.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
|
|
</div>
|
|
|
|
<p>There are two kinds of environment variables that affect
|
|
the Apache HTTP Server.</p>
|
|
|
|
<p>First, there are the environment variables controlled by
|
|
the underlying operating system. These are set before the
|
|
server starts. They can be used in expansions in configuration
|
|
files, and can optionally be passed to CGI scripts and SSI
|
|
using the PassEnv directive.</p>
|
|
|
|
<p>Second, the Apache HTTP Server provides a mechanism for storing
|
|
information in named variables that are also called <em>environment
|
|
variables</em>. This information can be used to control various
|
|
operations such as logging or access control. The variables are
|
|
also used as a mechanism to communicate with external programs
|
|
such as CGI scripts. This document discusses different ways to
|
|
manipulate and use these variables.</p>
|
|
|
|
<p>Although these variables are referred to as <em>environment
|
|
variables</em>, they are not the same as the environment
|
|
variables controlled by the underlying operating system.
|
|
Instead, these variables are stored and manipulated in an
|
|
internal Apache structure. They only become actual operating
|
|
system environment variables when they are provided to CGI
|
|
scripts and Server Side Include scripts. If you wish to
|
|
manipulate the operating system environment under which the
|
|
server itself runs, you must use the standard environment
|
|
manipulation mechanisms provided by your operating system
|
|
shell.</p>
|
|
</div>
|
|
<div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#setting">Setting Environment Variables</a></li>
|
|
<li><img alt="" src="./images/down.gif" /> <a href="#using">Using Environment Variables</a></li>
|
|
<li><img alt="" src="./images/down.gif" /> <a href="#special">Special Purpose Environment Variables</a></li>
|
|
<li><img alt="" src="./images/down.gif" /> <a href="#examples">Examples</a></li>
|
|
</ul><h3>See also</h3><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
|
|
<div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
|
|
<div class="section">
|
|
<h2><a name="setting" id="setting">Setting Environment Variables</a> <a title="Permanent link" href="#setting" class="permalink">¶</a></h2>
|
|
|
|
<table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="./mod/mod_cache.html">mod_cache</a></code></li><li><code class="module"><a href="./mod/mod_env.html">mod_env</a></code></li><li><code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code></li><li><code class="module"><a href="./mod/mod_setenvif.html">mod_setenvif</a></code></li><li><code class="module"><a href="./mod/mod_unique_id.html">mod_unique_id</a></code></li></ul></td><td><ul><li><code class="directive"><a href="./mod/mod_setenvif.html#browsermatch">BrowserMatch</a></code></li><li><code class="directive"><a href="./mod/mod_setenvif.html#browsermatchnocase">BrowserMatchNoCase</a></code></li><li><code class="directive"><a href="./mod/mod_env.html#passenv">PassEnv</a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewriterule">RewriteRule</a></code></li><li><code class="directive"><a href="./mod/mod_env.html#setenv">SetEnv</a></code></li><li><code class="directive"><a href="./mod/mod_setenvif.html#setenvif">SetEnvIf</a></code></li><li><code class="directive"><a href="./mod/mod_setenvif.html#setenvifnocase">SetEnvIfNoCase</a></code></li><li><code class="directive"><a href="./mod/mod_env.html#unsetenv">UnsetEnv</a></code></li></ul></td></tr></table>
|
|
|
|
<h3><a name="basic-manipulation" id="basic-manipulation">Basic Environment Manipulation</a></h3>
|
|
|
|
|
|
<p>The most basic way to set an environment variable in Apache
|
|
is using the unconditional <code class="directive"><a href="./mod/mod_env.html#setenv">SetEnv</a></code> directive. Variables may also be passed from
|
|
the environment of the shell which started the server using the
|
|
<code class="directive"><a href="./mod/mod_env.html#passenv">PassEnv</a></code> directive.</p>
|
|
|
|
|
|
<h3><a name="conditional" id="conditional">Conditional Per-Request Settings</a></h3>
|
|
|
|
|
|
<p>For additional flexibility, the directives provided by
|
|
<code class="module"><a href="./mod/mod_setenvif.html">mod_setenvif</a></code> allow environment variables to be set
|
|
on a per-request basis, conditional on characteristics of particular
|
|
requests. For example, a variable could be set only when a
|
|
specific browser (User-Agent) is making a request, or only when
|
|
a specific Referer [sic] header is found. Even more flexibility
|
|
is available through the <code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code>'s <code class="directive"><a href="./mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> which uses the
|
|
<code>[E=...]</code> option to set environment variables.</p>
|
|
|
|
|
|
<h3><a name="unique-identifiers" id="unique-identifiers">Unique Identifiers</a></h3>
|
|
|
|
|
|
<p>Finally, <code class="module"><a href="./mod/mod_unique_id.html">mod_unique_id</a></code> sets the environment
|
|
variable <code>UNIQUE_ID</code> for each request to a value which is
|
|
guaranteed to be unique across "all" requests under very
|
|
specific conditions.</p>
|
|
|
|
|
|
<h3><a name="standard-cgi" id="standard-cgi">Standard CGI Variables</a></h3>
|
|
|
|
|
|
<p>In addition to all environment variables set within the
|
|
Apache configuration and passed from the shell, CGI scripts and
|
|
SSI pages are provided with a set of environment variables
|
|
containing meta-information about the request as required by
|
|
the <a href="http://www.ietf.org/rfc/rfc3875">CGI
|
|
specification</a>.</p>
|
|
|
|
|
|
<h3><a name="caveats" id="caveats">Some Caveats</a></h3>
|
|
|
|
|
|
<ul>
|
|
<li>It is not possible to override or change the standard CGI
|
|
variables using the environment manipulation directives.</li>
|
|
|
|
<li>When <code class="program"><a href="./programs/suexec.html">suexec</a></code> is used to launch
|
|
CGI scripts, the environment will be cleaned down to a set of
|
|
<em>safe</em> variables before CGI scripts are launched. The
|
|
list of <em>safe</em> variables is defined at compile-time in
|
|
<code>suexec.c</code>.</li>
|
|
|
|
<li>For portability reasons, the names of environment
|
|
variables may contain only letters, numbers, and the
|
|
underscore character. In addition, the first character may
|
|
not be a number. Characters which do not match this
|
|
restriction will be replaced by an underscore when passed to
|
|
CGI scripts and SSI pages.</li>
|
|
|
|
<li>A special case are HTTP headers which are passed to CGI
|
|
scripts and the like via environment variables (see below).
|
|
They are converted to uppercase and only dashes are replaced with
|
|
underscores; if the header contains any other (invalid) character,
|
|
the whole header is silently dropped. See <a href="#fixheader">
|
|
below</a> for a workaround.</li>
|
|
|
|
<li>The <code class="directive"><a href="./mod/mod_env.html#setenv">SetEnv</a></code> directive runs
|
|
late during request processing meaning that directives such as
|
|
<code class="directive"><a href="./mod/mod_setenvif.html#setenvif">SetEnvIf</a></code> and <code class="directive"><a href="./mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> will not see the
|
|
variables set with it.</li>
|
|
|
|
<li>When the server looks up a path via an internal
|
|
<a class="glossarylink" href="./glossary.html#subrequest" title="see glossary">subrequest</a> such as looking
|
|
for a <code class="directive"><a href="./mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
|
|
or generating a directory listing with <code class="module"><a href="./mod/mod_autoindex.html">mod_autoindex</a></code>,
|
|
per-request environment variables are <em>not</em> inherited in the
|
|
subrequest. Additionally,
|
|
<code class="directive"><a href="./mod/mod_setenvif.html#setenvif">SetEnvIf</a></code> directives
|
|
are not separately evaluated in the subrequest due to the API phases
|
|
<code class="module"><a href="./mod/mod_setenvif.html">mod_setenvif</a></code> takes action in.</li>
|
|
</ul>
|
|
|
|
</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
|
|
<div class="section">
|
|
<h2><a name="using" id="using">Using Environment Variables</a> <a title="Permanent link" href="#using" class="permalink">¶</a></h2>
|
|
|
|
|
|
<table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="./mod/mod_authz_host.html">mod_authz_host</a></code></li><li><code class="module"><a href="./mod/mod_cgi.html">mod_cgi</a></code></li><li><code class="module"><a href="./mod/mod_ext_filter.html">mod_ext_filter</a></code></li><li><code class="module"><a href="./mod/mod_headers.html">mod_headers</a></code></li><li><code class="module"><a href="./mod/mod_include.html">mod_include</a></code></li><li><code class="module"><a href="./mod/mod_log_config.html">mod_log_config</a></code></li><li><code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code></li></ul></td><td><ul><li><code class="directive"><a href="./mod/mod_authz_core.html#require">Require</a></code></li><li><code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code></li><li><code class="directive"><a href="./mod/mod_access_compat.html#allow">Allow</a></code></li><li><code class="directive"><a href="./mod/mod_access_compat.html#deny">Deny</a></code></li><li><code class="directive"><a href="./mod/mod_ext_filter.html#extfilterdefine">ExtFilterDefine</a></code></li><li><code class="directive"><a href="./mod/mod_headers.html#header">Header</a></code></li><li><code class="directive"><a href="./mod/mod_log_config.html#logformat">LogFormat</a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewritecond">RewriteCond</a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewriterule">RewriteRule</a></code></li></ul></td></tr></table>
|
|
|
|
<h3><a name="cgi-scripts" id="cgi-scripts">CGI Scripts</a></h3>
|
|
|
|
|
|
<p>One of the primary uses of environment variables is to
|
|
communicate information to CGI scripts. As discussed above, the
|
|
environment passed to CGI scripts includes standard
|
|
meta-information about the request in addition to any variables
|
|
set within the Apache configuration. For more details, see the
|
|
<a href="howto/cgi.html">CGI tutorial</a>.</p>
|
|
|
|
|
|
<h3><a name="ssi-pages" id="ssi-pages">SSI Pages</a></h3>
|
|
|
|
|
|
<p>Server-parsed (SSI) documents processed by
|
|
<code class="module"><a href="./mod/mod_include.html">mod_include</a></code>'s
|
|
<code>INCLUDES</code> filter can print environment variables
|
|
using the <code>echo</code> element, and can use environment
|
|
variables in flow control elements to makes parts of a page
|
|
conditional on characteristics of a request. Apache also
|
|
provides SSI pages with the standard CGI environment variables
|
|
as discussed above. For more details, see the <a href="howto/ssi.html">SSI tutorial</a>.</p>
|
|
|
|
|
|
<h3><a name="access-control" id="access-control">Access Control</a></h3>
|
|
|
|
|
|
<p>Access to the server can be controlled based on
|
|
environment variables using the <code>Require env</code>
|
|
and <code>Require not env</code> directives. In combination with
|
|
<code class="directive"><a href="./mod/mod_setenvif.html#setenvif">SetEnvIf</a></code>, this
|
|
allows for flexible control of access to the server based on
|
|
characteristics of the client. For example, you can use these
|
|
directives to deny access to a particular browser (User-Agent).
|
|
</p>
|
|
|
|
|
|
<h3><a name="logging" id="logging">Conditional Logging</a></h3>
|
|
|
|
|
|
<p>Environment variables can be logged in the access log using
|
|
the <code class="directive"><a href="./mod/mod_log_config.html#logformat">LogFormat</a></code>
|
|
option <code>%e</code>. In addition, the decision on whether
|
|
or not to log requests can be made based on the status of
|
|
environment variables using the conditional form of the
|
|
<code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code>
|
|
directive. In combination with <code class="directive"><a href="./mod/mod_setenvif.html#setenvif">SetEnvIf</a></code> this allows for flexible control of which
|
|
requests are logged. For example, you can choose not to log
|
|
requests for filenames ending in <code>gif</code>, or you can
|
|
choose to only log requests from clients which are outside your
|
|
subnet.</p>
|
|
|
|
|
|
<h3><a name="response-headers" id="response-headers">Conditional Response Headers</a></h3>
|
|
|
|
|
|
<p>The <code class="directive"><a href="./mod/mod_headers.html#header">Header</a></code>
|
|
directive can use the presence or
|
|
absence of an environment variable to determine whether or not
|
|
a certain HTTP header will be placed in the response to the
|
|
client. This allows, for example, a certain response header to
|
|
be sent only if a corresponding header is received in the
|
|
request from the client.</p>
|
|
|
|
|
|
|
|
<h3><a name="external-filter" id="external-filter">External Filter Activation</a></h3>
|
|
|
|
|
|
<p>External filters configured by <code class="module"><a href="./mod/mod_ext_filter.html">mod_ext_filter</a></code>
|
|
using the <code class="directive"><a href="./mod/mod_ext_filter.html#extfilterdefine">ExtFilterDefine</a></code> directive can
|
|
by activated conditional on an environment variable using the
|
|
<code>disableenv=</code> and <code>enableenv=</code> options.</p>
|
|
|
|
|
|
<h3><a name="url-rewriting" id="url-rewriting">URL Rewriting</a></h3>
|
|
|
|
|
|
<p>The <code>%{ENV:<em>variable</em>}</code> form of
|
|
<em>TestString</em> in the <code class="directive"><a href="./mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> allows <code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code>'s rewrite
|
|
engine to make decisions conditional on environment variables.
|
|
Note that the variables accessible in <code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code>
|
|
without the <code>ENV:</code> prefix are not actually environment
|
|
variables. Rather, they are variables special to
|
|
<code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code> which cannot be accessed from other
|
|
modules.</p>
|
|
|
|
</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
|
|
<div class="section">
|
|
<h2><a name="special" id="special">Special Purpose Environment Variables</a> <a title="Permanent link" href="#special" class="permalink">¶</a></h2>
|
|
|
|
|
|
<p>Interoperability problems have led to the introduction of
|
|
mechanisms to modify the way Apache behaves when talking to
|
|
particular clients. To make these mechanisms as flexible as
|
|
possible, they are invoked by defining environment variables,
|
|
typically with <code class="directive"><a href="./mod/mod_setenvif.html#browsermatch">BrowserMatch</a></code>, though <code class="directive"><a href="./mod/mod_env.html#setenv">SetEnv</a></code> and <code class="directive"><a href="./mod/mod_env.html#passenv">PassEnv</a></code> could also be used, for example.</p>
|
|
|
|
<h3><a name="downgrade" id="downgrade">downgrade-1.0</a></h3>
|
|
|
|
|
|
<p>This forces the request to be treated as a HTTP/1.0 request
|
|
even if it was in a later dialect.</p>
|
|
|
|
|
|
<h3><a name="force-gzip" id="force-gzip">force-gzip</a></h3>
|
|
|
|
<p>If you have the <code>DEFLATE</code> filter activated, this
|
|
environment variable will ignore the accept-encoding setting of
|
|
your browser and will send compressed output unconditionally.</p>
|
|
|
|
<h3><a name="force-no-vary" id="force-no-vary">force-no-vary</a></h3>
|
|
|
|
|
|
<p>This causes any <code>Vary</code> fields to be removed from
|
|
the response header before it is sent back to the client. Some
|
|
clients don't interpret this field correctly; setting this
|
|
variable can work around this problem. Setting this variable
|
|
also implies <strong>force-response-1.0</strong>.</p>
|
|
|
|
|
|
<h3><a name="force-response" id="force-response">force-response-1.0</a></h3>
|
|
|
|
|
|
<p>This forces an HTTP/1.0 response to clients making an HTTP/1.0
|
|
request. It was originally
|
|
implemented as a result of a problem with AOL's proxies. Some
|
|
HTTP/1.0 clients may not behave correctly when given an HTTP/1.1
|
|
response, and this can be used to interoperate with them.</p>
|
|
|
|
|
|
|
|
<h3><a name="gzip-only-text-html" id="gzip-only-text-html">gzip-only-text/html</a></h3>
|
|
|
|
|
|
<p>When set to a value of "1", this variable disables the
|
|
<code>DEFLATE</code> output filter provided by
|
|
<code class="module"><a href="./mod/mod_deflate.html">mod_deflate</a></code> for content-types other than
|
|
<code>text/html</code>. If you'd rather
|
|
use statically compressed files, <code class="module"><a href="./mod/mod_negotiation.html">mod_negotiation</a></code>
|
|
evaluates the variable as well (not only for gzip, but for all
|
|
encodings that differ from "identity").</p>
|
|
|
|
|
|
<h3><a name="no-gzip" id="no-gzip">no-gzip</a></h3>
|
|
|
|
<p>When set, the <code>DEFLATE</code> filter of
|
|
<code class="module"><a href="./mod/mod_deflate.html">mod_deflate</a></code> will be turned off and
|
|
<code class="module"><a href="./mod/mod_negotiation.html">mod_negotiation</a></code> will refuse to deliver encoded
|
|
resources.</p>
|
|
|
|
|
|
|
|
<h3><a name="no-cache" id="no-cache">no-cache</a></h3>
|
|
<p><em>Available in versions 2.2.12 and later</em></p>
|
|
|
|
<p>When set, <code class="module"><a href="./mod/mod_cache.html">mod_cache</a></code> will not save an otherwise
|
|
cacheable response. This environment variable does not influence
|
|
whether a response already in the cache will be served for the current
|
|
request.</p>
|
|
|
|
|
|
|
|
<h3><a name="nokeepalive" id="nokeepalive">nokeepalive</a></h3>
|
|
|
|
|
|
<p>This disables <code class="directive"><a href="./mod/core.html#keepalive">KeepAlive</a></code>
|
|
when set.</p>
|
|
|
|
|
|
|
|
<h3><a name="prefer-language" id="prefer-language">prefer-language</a></h3>
|
|
|
|
<p>This influences <code class="module"><a href="./mod/mod_negotiation.html">mod_negotiation</a></code>'s behaviour. If
|
|
it contains a language tag (such as <code>en</code>, <code>ja</code>
|
|
or <code>x-klingon</code>), <code class="module"><a href="./mod/mod_negotiation.html">mod_negotiation</a></code> tries
|
|
to deliver a variant with that language. If there's no such variant,
|
|
the normal <a href="content-negotiation.html">negotiation</a> process
|
|
applies.</p>
|
|
|
|
|
|
|
|
<h3><a name="redirect-carefully" id="redirect-carefully">redirect-carefully</a></h3>
|
|
|
|
|
|
<p>This forces the server to be more careful when sending a redirect
|
|
to the client. This is typically used when a client has a known
|
|
problem handling redirects. This was originally implemented as a
|
|
result of a problem with Microsoft's WebFolders software which has
|
|
a problem handling redirects on directory resources via DAV
|
|
methods.</p>
|
|
|
|
|
|
|
|
<h3><a name="suppress-error-charset" id="suppress-error-charset">suppress-error-charset</a></h3>
|
|
|
|
|
|
<p><em>Available in versions after 2.0.54</em></p>
|
|
|
|
<p>When Apache issues a redirect in response to a client request,
|
|
the response includes some actual text to be displayed in case
|
|
the client can't (or doesn't) automatically follow the redirection.
|
|
Apache ordinarily labels this text according to the character set
|
|
which it uses, which is ISO-8859-1.</p>
|
|
|
|
<p> However, if the redirection is to a page that uses a different
|
|
character set, some broken browser versions will try to use the
|
|
character set from the redirection text rather than the actual page.
|
|
This can result in Greek, for instance, being incorrectly rendered.</p>
|
|
|
|
<p>Setting this environment variable causes Apache to omit the character
|
|
set for the redirection text, and these broken browsers will then correctly
|
|
use that of the destination page.</p>
|
|
|
|
<div class="warning">
|
|
<h3>Security note</h3>
|
|
|
|
<p>Sending error pages without a specified character set may
|
|
allow a cross-site-scripting attack for existing browsers (MSIE)
|
|
which do not follow the HTTP/1.1 specification and attempt to
|
|
"guess" the character set from the content. Such browsers can
|
|
be easily fooled into using the UTF-7 character set, and UTF-7
|
|
content from input data (such as the request-URI) will not be
|
|
escaped by the usual escaping mechanisms designed to prevent
|
|
cross-site-scripting attacks.</p>
|
|
</div>
|
|
|
|
|
|
|
|
<h3><a name="proxy" id="proxy">force-proxy-request-1.0, proxy-nokeepalive, proxy-sendchunked,
|
|
proxy-sendcl, proxy-chain-auth, proxy-interim-response, proxy-initial-not-pooled</a></h3>
|
|
|
|
<p>These directives alter the protocol behavior of
|
|
<code class="module"><a href="./mod/mod_proxy.html">mod_proxy</a></code>. See the <code class="module"><a href="./mod/mod_proxy.html">mod_proxy</a></code> and <code class="module"><a href="./mod/mod_proxy_http.html">mod_proxy_http</a></code>
|
|
documentation for more details.</p>
|
|
|
|
|
|
<h3><a name="cgilike" id="cgilike">ap_trust_cgilike_cl</a></h3>
|
|
<p><em>Available in 2.4.59 and later</em></p>
|
|
<p> This variable allows a script running in CGI-like module to supply it's
|
|
own Content-Length HTTP response header. It should
|
|
only be set on configuration sections that contain trusted scripts.
|
|
</p>
|
|
|
|
|
|
</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
|
|
<div class="section">
|
|
<h2><a name="examples" id="examples">Examples</a> <a title="Permanent link" href="#examples" class="permalink">¶</a></h2>
|
|
|
|
|
|
<h3><a name="fixheader" id="fixheader">Passing broken headers to CGI scripts</a></h3>
|
|
|
|
|
|
<p>Starting with version 2.4, Apache is more strict about how HTTP
|
|
headers are converted to environment variables in <code class="module"><a href="./mod/mod_cgi.html">mod_cgi
|
|
</a></code> and other modules: Previously any invalid characters
|
|
in header names were simply translated to underscores. This allowed
|
|
for some potential cross-site-scripting attacks via header injection
|
|
(see <a href="http://events.ccc.de/congress/2007/Fahrplan/events/2212.en.html">
|
|
Unusual Web Bugs</a>, slide 19/20).</p>
|
|
|
|
<p>If you have to support a client which sends broken headers and
|
|
which can't be fixed, a simple workaround involving <code class="module"><a href="./mod/mod_setenvif.html">mod_setenvif
|
|
</a></code> and <code class="module"><a href="./mod/mod_headers.html">mod_headers</a></code> allows you to still accept
|
|
these headers:</p>
|
|
|
|
<pre class="prettyprint lang-config">#
|
|
# The following works around a client sending a broken Accept_Encoding
|
|
# header.
|
|
#
|
|
SetEnvIfNoCase ^Accept.Encoding$ ^(.*)$ fix_accept_encoding=$1
|
|
RequestHeader set Accept-Encoding %{fix_accept_encoding}e env=fix_accept_encoding</pre>
|
|
|
|
|
|
|
|
|
|
<h3><a name="misbehaving" id="misbehaving">Changing protocol behavior with misbehaving clients</a></h3>
|
|
|
|
|
|
<p>Earlier versions recommended that the following lines be included in
|
|
httpd.conf to deal with known client problems. Since the affected clients
|
|
are no longer seen in the wild, this configuration is likely no-longer
|
|
necessary.</p>
|
|
<pre class="prettyprint lang-config">#
|
|
# The following directives modify normal HTTP response behavior.
|
|
# The first directive disables keepalive for Netscape 2.x and browsers that
|
|
# spoof it. There are known problems with these browser implementations.
|
|
# The second directive is for Microsoft Internet Explorer 4.0b2
|
|
# which has a broken HTTP/1.1 implementation and does not properly
|
|
# support keepalive when it is used on 301 or 302 (redirect) responses.
|
|
#
|
|
BrowserMatch "Mozilla/2" nokeepalive
|
|
BrowserMatch "MSIE 4\.0b2;" nokeepalive downgrade-1.0 force-response-1.0
|
|
|
|
#
|
|
# The following directive disables HTTP/1.1 responses to browsers which
|
|
# are in violation of the HTTP/1.0 spec by not being able to understand a
|
|
# basic 1.1 response.
|
|
#
|
|
BrowserMatch "RealPlayer 4\.0" force-response-1.0
|
|
BrowserMatch "Java/1\.0" force-response-1.0
|
|
BrowserMatch "JDK/1\.0" force-response-1.0</pre>
|
|
|
|
|
|
|
|
<h3><a name="no-img-log" id="no-img-log">Do not log requests for images in the access log</a></h3>
|
|
|
|
|
|
<p>This example keeps requests for images from appearing in the
|
|
access log. It can be easily modified to prevent logging of
|
|
particular directories, or to prevent logging of requests
|
|
coming from particular hosts.</p>
|
|
|
|
<pre class="prettyprint lang-config">SetEnvIf Request_URI \.gif image-request
|
|
SetEnvIf Request_URI \.jpg image-request
|
|
SetEnvIf Request_URI \.png image-request
|
|
CustomLog "logs/access_log" common env=!image-request</pre>
|
|
|
|
|
|
|
|
<h3><a name="image-theft" id="image-theft">Prevent "Image Theft"</a></h3>
|
|
|
|
|
|
<p>This example shows how to keep people not on your server
|
|
from using images on your server as inline-images on their
|
|
pages. This is not a recommended configuration, but it can work
|
|
in limited circumstances. We assume that all your images are in
|
|
a directory called <code>/web/images</code>.</p>
|
|
|
|
<pre class="prettyprint lang-config">SetEnvIf Referer "^http://www\.example\.com/" local_referal
|
|
# Allow browsers that do not send Referer info
|
|
SetEnvIf Referer "^$" local_referal
|
|
<Directory "/web/images">
|
|
Require env local_referal
|
|
</Directory></pre>
|
|
|
|
|
|
<p>For more information about this technique, see the
|
|
"<a href="https://www.serverwatch.com/guides/keeping-your-images-from-adorning-other-sites/">Keeping Your Images from Adorning Other Sites</a>"
|
|
tutorial on ServerWatch.</p>
|
|
|
|
</div></div>
|
|
<div class="bottomlang">
|
|
<p><span>Available Languages: </span><a href="./en/env.html" title="English"> en </a> |
|
|
<a href="./fr/env.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
|
|
<a href="./ja/env.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
|
|
<a href="./ko/env.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
|
|
<a href="./tr/env.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
|
|
</div><div class="top"><a href="#page-header"><img src="./images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
|
|
<script type="text/javascript"><!--//--><![CDATA[//><!--
|
|
var comments_shortname = 'httpd';
|
|
var comments_identifier = 'http://httpd.apache.org/docs/trunk/env.html';
|
|
(function(w, d) {
|
|
if (w.location.hostname.toLowerCase() == "httpd.apache.org") {
|
|
d.write('<div id="comments_thread"><\/div>');
|
|
var s = d.createElement('script');
|
|
s.type = 'text/javascript';
|
|
s.async = true;
|
|
s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier;
|
|
(d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s);
|
|
}
|
|
else {
|
|
d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>');
|
|
}
|
|
})(window, document);
|
|
//--><!]]></script></div><div id="footer">
|
|
<p class="apache">Copyright 2024 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
|
|
<p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p></div><script type="text/javascript"><!--//--><![CDATA[//><!--
|
|
if (typeof(prettyPrint) !== 'undefined') {
|
|
prettyPrint();
|
|
}
|
|
//--><!]]></script>
|
|
</body></html> |