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10 <title>mod_policy - Apache HTTP Server Version 2.5</title>
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21 <p class="apache">Apache HTTP Server Version 2.5</p>
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25 <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> > <a href="./">Modules</a></div>
26 <div id="page-content">
27 <div id="preamble"><h1>Apache Module mod_policy</h1>
29 <p><span>Available Languages: </span><a href="../en/mod/mod_policy.html" title="English"> en </a></p>
31 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>HTTP protocol compliance enforcement.</td></tr>
32 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
33 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>policy_module</td></tr>
34 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_policy.c</td></tr></table>
37 <p>The HTTP protocol recommends that clients should be "liberal in
38 what they accept", and servers "strict with what they send". In some
39 cases it can be difficult to detect when a server or an application
40 has been misconfigured, is serving uncacheable content or is behaving
41 suboptimally, as an HTTP client might be compensating for the server.
42 These problems can potentially lead to excessive bandwidth
43 consumption, or a server outage under load.</p>
45 <p>The <code class="module"><a href="../mod/mod_policy.html">mod_policy</a></code> module consists of a set of
46 filters that test servers for HTTP protocol compliance. These
47 tests allow the server administrator to log violations of, or
48 outright reject responses where certain defined conditions exist.</p>
50 <p>This could be used as a way to set minimum HTTP protocol compliance
51 criteria for a restful application. Alternatively, a reverse proxy or
52 cache could be configured to protect itself from misconfigured origin
53 servers or unexpectedly uncacheable content, or as a mechanism to
54 detect configuration mistakes within the server itself.</p>
57 <div id="quickview"><h3>Topics</h3>
59 <li><img alt="" src="../images/down.gif" /> <a href="#actions">Actions</a></li>
60 <li><img alt="" src="../images/down.gif" /> <a href="#tests">Policy Tests</a></li>
61 <li><img alt="" src="../images/down.gif" /> <a href="#example">Example Configuration</a></li>
62 </ul><h3 class="directives">Directives</h3>
64 <li><img alt="" src="../images/down.gif" /> <a href="#policyconditional">PolicyConditional</a></li>
65 <li><img alt="" src="../images/down.gif" /> <a href="#policyconditionalurl">PolicyConditionalURL</a></li>
66 <li><img alt="" src="../images/down.gif" /> <a href="#policyenvironment">PolicyEnvironment</a></li>
67 <li><img alt="" src="../images/down.gif" /> <a href="#policyfilter">PolicyFilter</a></li>
68 <li><img alt="" src="../images/down.gif" /> <a href="#policykeepalive">PolicyKeepalive</a></li>
69 <li><img alt="" src="../images/down.gif" /> <a href="#policykeepaliveurl">PolicyKeepaliveURL</a></li>
70 <li><img alt="" src="../images/down.gif" /> <a href="#policylength">PolicyLength</a></li>
71 <li><img alt="" src="../images/down.gif" /> <a href="#policylengthurl">PolicyLengthURL</a></li>
72 <li><img alt="" src="../images/down.gif" /> <a href="#policymaxage">PolicyMaxage</a></li>
73 <li><img alt="" src="../images/down.gif" /> <a href="#policymaxageurl">PolicyMaxageURL</a></li>
74 <li><img alt="" src="../images/down.gif" /> <a href="#policynocache">PolicyNocache</a></li>
75 <li><img alt="" src="../images/down.gif" /> <a href="#policynocacheurl">PolicyNocacheURL</a></li>
76 <li><img alt="" src="../images/down.gif" /> <a href="#policytype">PolicyType</a></li>
77 <li><img alt="" src="../images/down.gif" /> <a href="#policytypeurl">PolicyTypeURL</a></li>
78 <li><img alt="" src="../images/down.gif" /> <a href="#policyvalidation">PolicyValidation</a></li>
79 <li><img alt="" src="../images/down.gif" /> <a href="#policyvalidationurl">PolicyValidationURL</a></li>
80 <li><img alt="" src="../images/down.gif" /> <a href="#policyvary">PolicyVary</a></li>
81 <li><img alt="" src="../images/down.gif" /> <a href="#policyvaryurl">PolicyVaryURL</a></li>
82 <li><img alt="" src="../images/down.gif" /> <a href="#policyversion">PolicyVersion</a></li>
83 <li><img alt="" src="../images/down.gif" /> <a href="#policyversionurl">PolicyVersionURL</a></li>
85 <h3>Bugfix checklist:</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">HTTPD changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=mod_policy">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2">Report a bug</a></li></ul><h3>See also</h3>
87 <li><a href="../filter.html">Filters</a></li>
88 <li><a href="../compliance.html">HTTP Protocol Compliance</a></li>
89 </ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
90 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
92 <h2><a name="actions" id="actions">Actions</a></h2>
95 <p>If a policy is violated, one of the following actions can be
99 <dt><strong>ignore</strong></dt>
100 <dd>The policy check will be ignored for the given URL space, even
101 if the filter is present.</dd>
103 <dt><strong>log</strong></dt>
104 <dd>The policy check will be executed, and if a violation is detected
105 a warning will be logged to the server error_log, and a
106 <code>Warning</code> header added to the response for the benefit of
109 <dt><strong>enforce</strong></dt>
110 <dd>The policy check will be executed, and if a violation is detected
111 an error will be logged to the server error_log, a
112 <code>Warning</code> header added to the response, and a <code>502
113 Bad Gateway</code> will be returned to the client. Optional links to
114 explanatory documentation can be added to each error message,
115 detailing the origin of each policy.</dd>
119 <p>It is also possible to selectively disable all policies for a
120 given URL space, should the need arise, using the
121 <code class="directive"><a href="#policyfilter">PolicyFilter</a></code> directive.</p>
123 <p>Alternatively, the
124 <code class="directive"><a href="#policyenvironment">PolicyEnvironment</a></code>
125 directive can be used to specify an environment variable, which if
126 present, will cause the policies to be selectively downgraded or
129 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
130 <div class="section">
131 <h2><a name="tests" id="tests">Policy Tests</a></h2>
134 <p>The following policy filters are available:</p>
137 <dt><strong><a href="../compliance.html#policytype">POLICY_TYPE</a>
138 </strong>: Enforce valid content types</dt>
139 <dd>Content types that are syntactically invalid or blank can be detected
140 and the request rejected. Types can be restricted to a specific list
141 containing optional wildcards ? and *.</dd>
143 <dt><strong><a href="../compliance.html#policylength">POLICY_LENGTH</a>
144 </strong>: Enforce the presence of a Content-Length</dt>
145 <dd>The length of responses can be specified in one of three ways, by
146 specifying an explicit length in advance, using chunked encoding to set
147 the length, or by setting no length at all and terminating the request
148 when complete. The absence of a specific content length can affect the
149 cacheability of the response, and prevents the use of keepalive during
150 HTTP/1.0 requests. This policy enforces the presence of an explicit
151 content length on the response.</dd>
153 <dt><strong><a href="../compliance.html#policykeepalive">POLICY_KEEPALIVE
154 </a></strong>: Enforce the option to keepalive</dt>
155 <dd>Less restrictive than the POLICY_LENGTH test, this policy enforces the
156 possibility that the response can be kept alive. If the response doesn't
157 have a protocol defined zero length, and the response isn't already an
158 error, and the response has neither a Content-Length or is declared
159 HTTP/1.1 and lacks Content-Encoding: chunked, then this response will be
162 <dt><strong><a href="../compliance.html#policyvary">POLICY_VARY</a>
163 </strong>: Enforce the absence of certain headers within Vary headers</dt>
164 <dd>If the Vary header contains any of the headers specified, this policy
165 will reject the request. The typical case is the presence of the User-Agent
166 within Vary, which is likely to cause a denial of service condition to a
169 <dt><strong><a href="../compliance.html#policyvalidation">
170 POLICY_VALIDATION</a></strong>: Enforce the presence of Etag and/or
172 <dd>The ability for a cache to determine whether a cached entity can be
173 refreshed is dependent on whether a valid Etag and/or Last-Modified header
174 is present to revalidate against. The absence of both headers, or the
175 invalid syntax of a header will cause this policy to be rejected.</dd>
177 <dt><strong><a href="../compliance.html#policyconditional">
178 POLICY_CONDITIONAL</a></strong>: Enforce correct operation of conditional
180 <dd>When conditional headers are present in the request, a server should
181 respond with a <code>304 Not Modified</code> or <code>412 Precondition
182 Failed</code> response where appropriate. A server may ignore conditional
183 headers, and this affects the efficiency of the HTTP caching mechanism.
184 This policy rejects requests where a conditional header is present, and
185 a 304 or 412 response code was expected, but a 2xx response was seen
188 <dt><strong><a href="../compliance.html#policynocache">POLICY_NOCACHE</a>
189 </strong>: Enforce cacheable responses</dt>
190 <dd>When a response is encountered that declares itself explicitly
191 uncacheable, the request is rejected. A response is considered
192 uncacheable if it specifies any of the following:
193 <ul><li><code>Cache-Control: no-cache</code></li>
194 <li><code>Pragma: no-cache</code></li>
195 <li><code>Cache-Control: no-store</code></li>
196 <li><code>Cache-Control: private</code></li>
199 <dt><strong><a href="../compliance.html#policymaxage">POLICY_MAXAGE</a>
200 </strong>: Enforce a minimum maxage</dt>
201 <dd>When a response is encountered where the freshness lifetime is less
202 than the given value, or the freshness lifetime is heuristic, the request
203 is rejected. A response is checked in the following order:
204 <ul><li>If <code>s-maxage</code> is present but too small; or</li>
205 <li>If <code>max-age</code> is present but too small; or</li>
206 <li>If <code>Expires</code> is present and invalid; or</li>
207 <li><code>Date</code> is present and invalid; or</li>
208 <li><code>Expires</code> minus Date is too small; or</li>
209 <li>No <code>s-maxage</code>, <code>maxage</code>, or
210 <code>Expires</code>/<code>Date</code> declared at all</li>
213 <dt><strong><a href="../compliance.html#policyversion">POLICY_VERSION</a>
214 </strong>: Enforce a minimum HTTP version within a request</dt>
215 <dd>When a request is encountered with an HTTP version number less than
216 the required minimum version, the request is rejected. The following
217 version numbers are recognised:
218 <ul><li><code>HTTP/1.1</code></li>
219 <li><code>HTTP/1.0</code></li>
220 <li><code>HTTP/0.9</code></li>
225 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
226 <div class="section">
227 <h2><a name="example" id="example">Example Configuration</a></h2>
230 <p>A typical configuration protecting a server serving static content
231 might be as follows:</p>
233 <pre class="prettyprint lang-config"><Location "/">
234 SetOutputFilter POLICY_TYPE;POLICY_LENGTH;POLICY_KEEPALIVE;POLICY_VARY;POLICY_VALIDATION; \
235 POLICY_CONDITIONAL;POLICY_NOCACHE;POLICY_MAXAGE;POLICY_VERSION
237 # content type must be present and valid, but can be anything
238 PolicyType enforce */*
240 # reject if no explicitly declared content length
243 # covered by the policy length filter
244 PolicyKeepalive ignore
246 # reject if User-Agent appears within Vary headers
247 PolicyVary enforce User-Agent
249 # we want to enforce validation
250 PolicyValidation enforce
252 # non-functional conditional responses should be rejected
253 PolicyConditional enforce
255 # no-cache responses should be rejected
256 PolicyNocache enforce
258 # maxage must be at least a day
259 PolicyMaxage enforce 86400
261 # request version can be anything
262 PolicyVersion ignore HTTP/1.1
265 # suppress policy protection for server-status
266 <Location "/server-status">
268 </Location></pre>
272 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
273 <div class="directive-section"><h2><a name="PolicyConditional" id="PolicyConditional">PolicyConditional</a> <a name="policyconditional" id="policyconditional">Directive</a></h2>
274 <table class="directive">
275 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the conditional request policy.</td></tr>
276 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyConditional <var>ignore|log|enforce</var></code></td></tr>
277 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
278 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
279 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
280 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
281 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyConditional is only available in Apache 2.5.0 and
284 <p>When logged or enforced, a response that should have been conditional
285 but wasn't will be rejected.</p>
287 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># non-functional conditional responses should be rejected
288 PolicyConditional enforce</pre>
292 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
293 <div class="directive-section"><h2><a name="PolicyConditionalURL" id="PolicyConditionalURL">PolicyConditionalURL</a> <a name="policyconditionalurl" id="policyconditionalurl">Directive</a></h2>
294 <table class="directive">
295 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the conditional request policy.</td></tr>
296 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyConditionalURL <var>url</var></code></td></tr>
297 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
298 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
299 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
300 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
301 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyConditionalURL is only available in Apache 2.5.0 and
304 <p>Specify the URL of the documentation describing the conditional
305 request policy, to appear within error messages.</p>
308 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
309 <div class="directive-section"><h2><a name="PolicyEnvironment" id="PolicyEnvironment">PolicyEnvironment</a> <a name="policyenvironment" id="policyenvironment">Directive</a></h2>
310 <table class="directive">
311 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Override policies based on an environment variable.</td></tr>
312 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyEnvironment <var>variable</var> <var>log-value</var> <var>ignore-value</var></code></td></tr>
313 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
314 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
315 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
316 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
317 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyEnvironment is only available in Apache 2.5.0 and
320 <p>Downgrade policies to logging only or ignored based on the presence
321 of an environment variable. If the given variable is present and equal
322 to the log-value, enforced policies will be logged instead. If the given
323 variable is present and equal to the ignore-value, all policies will
326 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># downgrade if POLICY_CONTROL was present
327 PolicyEnvironment POLICY_CONTROL log ignore</pre>
331 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
332 <div class="directive-section"><h2><a name="PolicyFilter" id="PolicyFilter">PolicyFilter</a> <a name="policyfilter" id="policyfilter">Directive</a></h2>
333 <table class="directive">
334 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable or disable policies for the given URL space.</td></tr>
335 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyFilter <var>on|off</var></code></td></tr>
336 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>on</code></td></tr>
337 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
338 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
339 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
340 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyFilter is only available in Apache 2.5.0 and
343 <p>Master switch to enable or disable policies for a given URL space.</p>
345 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># enabled by default
350 # suppress policy protection for server-status
351 <Location "/server-status">
353 </Location></pre>
357 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
358 <div class="directive-section"><h2><a name="PolicyKeepalive" id="PolicyKeepalive">PolicyKeepalive</a> <a name="policykeepalive" id="policykeepalive">Directive</a></h2>
359 <table class="directive">
360 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the keepalive policy.</td></tr>
361 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyKeepalive <var>ignore|log|enforce</var></code></td></tr>
362 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
363 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
364 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
365 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
366 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyKeepalive is only available in Apache 2.5.0 and
369 <p>When logged or enforced, a response that lacks both an explicit
370 <code>Content-Length</code> header and a <code>Transfer-Encoding</code>
371 of <code>chunked</code> will be rejected.</p>
373 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># missing Content-Length or Transfer-Encoding should be rejected
374 PolicyKeepalive enforce</pre>
378 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
379 <div class="directive-section"><h2><a name="PolicyKeepaliveURL" id="PolicyKeepaliveURL">PolicyKeepaliveURL</a> <a name="policykeepaliveurl" id="policykeepaliveurl">Directive</a></h2>
380 <table class="directive">
381 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the keepalive policy.</td></tr>
382 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyKeepaliveURL <var>url</var></code></td></tr>
383 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
384 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
385 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
386 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
387 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyKeepaliveURL is only available in Apache 2.5.0 and
390 <p>Specify the URL of the documentation describing the keepalive
391 policy, to appear within error messages.</p>
394 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
395 <div class="directive-section"><h2><a name="PolicyLength" id="PolicyLength">PolicyLength</a> <a name="policylength" id="policylength">Directive</a></h2>
396 <table class="directive">
397 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the content length policy.</td></tr>
398 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyLength <var>ignore|log|enforce</var></code></td></tr>
399 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
400 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
401 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
402 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
403 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyLength is only available in Apache 2.5.0 and
406 <p>When logged or enforced, a response that lacks an explicit
407 <code>Content-Length</code> header will be rejected.</p>
409 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># missing Content-Length header should be rejected
410 PolicyLength enforce</pre>
414 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
415 <div class="directive-section"><h2><a name="PolicyLengthURL" id="PolicyLengthURL">PolicyLengthURL</a> <a name="policylengthurl" id="policylengthurl">Directive</a></h2>
416 <table class="directive">
417 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the content length policy.</td></tr>
418 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyLengthURL <var>url</var></code></td></tr>
419 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
420 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
421 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
422 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
423 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyLengthURL is only available in Apache 2.5.0 and
426 <p>Specify the URL of the documentation describing the content length
427 policy, to appear within error messages.</p>
430 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
431 <div class="directive-section"><h2><a name="PolicyMaxage" id="PolicyMaxage">PolicyMaxage</a> <a name="policymaxage" id="policymaxage">Directive</a></h2>
432 <table class="directive">
433 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the caching minimum max-age policy.</td></tr>
434 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyMaxage <var>ignore|log|enforce</var> <var>age</var></code></td></tr>
435 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
436 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
437 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
438 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
439 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyMaxage is only available in Apache 2.5.0 and
442 <p>When logged or enforced, a response that lacks an explicit freshness
443 lifetime defined with <code>max-age</code>, <code>s-maxage</code> or an
444 <code>Expires</code> header, or where the explicit freshness lifetime is
445 smaller than the given value, will be rejected.</p>
447 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># reject responses with a freshness lifetime shorter than a day
448 PolicyMaxage enforce 86400</pre>
453 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
454 <div class="directive-section"><h2><a name="PolicyMaxageURL" id="PolicyMaxageURL">PolicyMaxageURL</a> <a name="policymaxageurl" id="policymaxageurl">Directive</a></h2>
455 <table class="directive">
456 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the caching minimum freshness lifetime policy.</td></tr>
457 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyMaxageURL <var>url</var></code></td></tr>
458 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
459 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
460 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
461 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
462 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyMaxageURL is only available in Apache 2.5.0 and
465 <p>Specify the URL of the documentation describing the caching minimum
466 freshness lifetime policy, to appear within error messages.</p>
469 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
470 <div class="directive-section"><h2><a name="PolicyNocache" id="PolicyNocache">PolicyNocache</a> <a name="policynocache" id="policynocache">Directive</a></h2>
471 <table class="directive">
472 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the caching no-cache policy.</td></tr>
473 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyNocache <var>ignore|log|enforce</var></code></td></tr>
474 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
475 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
476 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
477 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
478 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyNocache is only available in Apache 2.5.0 and
481 <p>When logged or enforced, a response that defines itself uncacheable
482 using the <code>Cache-Control</code> or <code>Pragma</code> headers will
485 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># Cache-Control: no-cache will be rejected
486 PolicyNocache enforce</pre>
491 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
492 <div class="directive-section"><h2><a name="PolicyNocacheURL" id="PolicyNocacheURL">PolicyNocacheURL</a> <a name="policynocacheurl" id="policynocacheurl">Directive</a></h2>
493 <table class="directive">
494 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the caching no-cache policy.</td></tr>
495 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyNocacheURL <var>url</var></code></td></tr>
496 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
497 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
498 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
499 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
500 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyNocacheURL is only available in Apache 2.5.0 and
503 <p>Specify the URL of the documentation describing the caching no-cache
504 policy, to appear within error messages.</p>
507 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
508 <div class="directive-section"><h2><a name="PolicyType" id="PolicyType">PolicyType</a> <a name="policytype" id="policytype">Directive</a></h2>
509 <table class="directive">
510 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the content type policy.</td></tr>
511 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyType <var>ignore|log|enforce</var> <var>type</var> [ <var>type</var> [ ... ]]</code></td></tr>
512 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
513 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
514 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
515 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
516 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyType is only available in Apache 2.5.0 and
519 <p>When logged or enforced, a response that lacks a <code>Content-Type</code>
520 header, where the <code>Content-Type</code> header is malformed, or where the
521 header does not match the given pattern or patterns will be rejected.</p>
523 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># enforce json or XML
524 PolicyType enforce application/json text/xml</pre>
527 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># malformed content type should be rejected
528 PolicyType enforce */*</pre>
533 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
534 <div class="directive-section"><h2><a name="PolicyTypeURL" id="PolicyTypeURL">PolicyTypeURL</a> <a name="policytypeurl" id="policytypeurl">Directive</a></h2>
535 <table class="directive">
536 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the content type policy.</td></tr>
537 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyTypeURL <var>url</var></code></td></tr>
538 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
539 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
540 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
541 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
542 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyTypeURL is only available in Apache 2.5.0 and
545 <p>Specify the URL of the documentation describing the content type
546 policy, to appear within error messages.</p>
549 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
550 <div class="directive-section"><h2><a name="PolicyValidation" id="PolicyValidation">PolicyValidation</a> <a name="policyvalidation" id="policyvalidation">Directive</a></h2>
551 <table class="directive">
552 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the validation policy.</td></tr>
553 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyValidation <var>ignore|log|enforce</var></code></td></tr>
554 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
555 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
556 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
557 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
558 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyValidation is only available in Apache 2.5.0 and
561 <p>When logged or enforced, a response that lacks either a valid
562 <code>ETag</code> header or a <code>Last-Modified</code> header, or where
563 either header is syntactically incorrect, will be rejected.</p>
565 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># no ETag or Last-Modified will be rejected
566 PolicyValidation enforce</pre>
571 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
572 <div class="directive-section"><h2><a name="PolicyValidationURL" id="PolicyValidationURL">PolicyValidationURL</a> <a name="policyvalidationurl" id="policyvalidationurl">Directive</a></h2>
573 <table class="directive">
574 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the content type policy.</td></tr>
575 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyValidationURL <var>url</var></code></td></tr>
576 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
577 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
578 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
579 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
580 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyValidationURL is only available in Apache 2.5.0 and
583 <p>Specify the URL of the documentation describing the validation policy, to
584 appear within error messages.</p>
587 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
588 <div class="directive-section"><h2><a name="PolicyVary" id="PolicyVary">PolicyVary</a> <a name="policyvary" id="policyvary">Directive</a></h2>
589 <table class="directive">
590 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the Vary policy.</td></tr>
591 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyVary <var>ignore|log|enforce</var> <var>header</var> [ <var>header</var> [ ... ]]</code></td></tr>
592 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
593 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
594 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
595 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
596 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyVary is only available in Apache 2.5.0 and
599 <p>When logged or enforced, a response that contains a <code>Vary</code>
600 header which in turn contains one of the headers listed, will be
603 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># reject reponses with "User-Agent" listed in the Vary header
604 PolicyVary enforce User-Agent</pre>
609 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
610 <div class="directive-section"><h2><a name="PolicyVaryURL" id="PolicyVaryURL">PolicyVaryURL</a> <a name="policyvaryurl" id="policyvaryurl">Directive</a></h2>
611 <table class="directive">
612 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the content type policy.</td></tr>
613 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyVaryURL <var>url</var></code></td></tr>
614 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
615 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
616 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
617 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
618 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyVaryURL is only available in Apache 2.5.0 and
621 <p>Specify the URL of the documentation describing the vary policy, to
622 appear within error messages.</p>
625 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
626 <div class="directive-section"><h2><a name="PolicyVersion" id="PolicyVersion">PolicyVersion</a> <a name="policyversion" id="policyversion">Directive</a></h2>
627 <table class="directive">
628 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable the version policy.</td></tr>
629 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyVersion <var>ignore|log|enforce</var> <var>HTTP/0.9|HTTP/1.0|HTTP/1.1</var></code></td></tr>
630 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ignore</code></td></tr>
631 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
632 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
633 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
634 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyVersion is only available in Apache 2.5.0 and
637 <p>When logged or enforced, a request with a version lower than specified
638 will be rejected.</p>
640 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config"># reject requests with an HTTP version older than HTTP/1.1
641 PolicyVersion enforce HTTP/1.1</pre>
646 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
647 <div class="directive-section"><h2><a name="PolicyVersionURL" id="PolicyVersionURL">PolicyVersionURL</a> <a name="policyversionurl" id="policyversionurl">Directive</a></h2>
648 <table class="directive">
649 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URL describing the minimum request HTTP version policy.</td></tr>
650 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PolicyVersionURL <var>url</var></code></td></tr>
651 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
652 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
653 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
654 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_policy</td></tr>
655 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>PolicyVersionURL is only available in Apache 2.5.0 and
658 <p>Specify the URL of the documentation describing the minimum request
659 HTTP version policy, to appear within error messages.</p>
663 <div class="bottomlang">
664 <p><span>Available Languages: </span><a href="../en/mod/mod_policy.html" title="English"> en </a></p>
665 </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 again 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 Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
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