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diff --git a/docs/manual/env.html.en b/docs/manual/env.html.en new file mode 100644 index 0000000..7876cdd --- /dev/null +++ b/docs/manual/env.html.en @@ -0,0 +1,529 @@ +<?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 2.4</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/directives.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 2.4</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 2.4</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"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><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></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></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></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> + + + </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></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="http://www.serverwatch.com/tutorials/article.php/1132731">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. 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