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23 <modulesynopsis metafile="mod_ssl.xml.meta">
26 <description>Strong cryptography using the Secure Sockets
27 Layer (SSL) and Transport Layer Security (TLS) protocols</description>
28 <status>Extension</status>
29 <sourcefile>mod_ssl.c</sourcefile>
30 <identifier>ssl_module</identifier>
33 <p>This module provides SSL v3 and TLS v1.x support for the Apache
34 HTTP Server. SSL v2 is no longer supported.</p>
36 <p>This module relies on <a href="http://www.openssl.org/">OpenSSL</a>
37 to provide the cryptography engine.</p>
39 <p>Further details, discussion, and examples are provided in the
40 <a href="../ssl/">SSL documentation</a>.</p>
43 <section id="envvars"><title>Environment Variables</title>
45 <p>This module can be configured to provide several items of SSL information
46 as additional environment variables to the SSI and CGI namespace. This
47 information is not provided by default for performance reasons. (See
48 <directive>SSLOptions</directive> StdEnvVars, below.) The generated variables
49 are listed in the table below. For backward compatibility the information can
50 be made available under different names, too. Look in the <a
51 href="../ssl/ssl_compat.html">Compatibility</a> chapter for details on the
52 compatibility variables.</p>
55 <columnspec><column width=".3"/><column width=".2"/><column width=".5"/>
58 <th><a name="table3">Variable Name:</a></th>
62 <tr><td><code>HTTPS</code></td> <td>flag</td> <td>HTTPS is being used.</td></tr>
63 <tr><td><code>SSL_PROTOCOL</code></td> <td>string</td> <td>The SSL protocol version (SSLv3, TLSv1, TLSv1.1, TLSv1.2)</td></tr>
64 <tr><td><code>SSL_SESSION_ID</code></td> <td>string</td> <td>The hex-encoded SSL session id</td></tr>
65 <tr><td><code>SSL_SESSION_RESUMED</code></td> <td>string</td> <td>Initial or Resumed SSL Session. Note: multiple requests may be served over the same (Initial or Resumed) SSL session if HTTP KeepAlive is in use</td></tr>
66 <tr><td><code>SSL_SECURE_RENEG</code></td> <td>string</td> <td><code>true</code> if secure renegotiation is supported, else <code>false</code></td></tr>
67 <tr><td><code>SSL_CIPHER</code></td> <td>string</td> <td>The cipher specification name</td></tr>
68 <tr><td><code>SSL_CIPHER_EXPORT</code></td> <td>string</td> <td><code>true</code> if cipher is an export cipher</td></tr>
69 <tr><td><code>SSL_CIPHER_USEKEYSIZE</code></td> <td>number</td> <td>Number of cipher bits (actually used)</td></tr>
70 <tr><td><code>SSL_CIPHER_ALGKEYSIZE</code></td> <td>number</td> <td>Number of cipher bits (possible)</td></tr>
71 <tr><td><code>SSL_COMPRESS_METHOD</code></td> <td>string</td> <td>SSL compression method negotiated</td></tr>
72 <tr><td><code>SSL_VERSION_INTERFACE</code></td> <td>string</td> <td>The mod_ssl program version</td></tr>
73 <tr><td><code>SSL_VERSION_LIBRARY</code></td> <td>string</td> <td>The OpenSSL program version</td></tr>
74 <tr><td><code>SSL_CLIENT_M_VERSION</code></td> <td>string</td> <td>The version of the client certificate</td></tr>
75 <tr><td><code>SSL_CLIENT_M_SERIAL</code></td> <td>string</td> <td>The serial of the client certificate</td></tr>
76 <tr><td><code>SSL_CLIENT_S_DN</code></td> <td>string</td> <td>Subject DN in client's certificate</td></tr>
77 <tr><td><code>SSL_CLIENT_S_DN_</code><em>x509</em></td> <td>string</td> <td>Component of client's Subject DN</td></tr>
78 <tr><td><code>SSL_CLIENT_I_DN</code></td> <td>string</td> <td>Issuer DN of client's certificate</td></tr>
79 <tr><td><code>SSL_CLIENT_I_DN_</code><em>x509</em></td> <td>string</td> <td>Component of client's Issuer DN</td></tr>
80 <tr><td><code>SSL_CLIENT_V_START</code></td> <td>string</td> <td>Validity of client's certificate (start time)</td></tr>
81 <tr><td><code>SSL_CLIENT_V_END</code></td> <td>string</td> <td>Validity of client's certificate (end time)</td></tr>
82 <tr><td><code>SSL_CLIENT_V_REMAIN</code></td> <td>string</td> <td>Number of days until client's certificate expires</td></tr>
83 <tr><td><code>SSL_CLIENT_A_SIG</code></td> <td>string</td> <td>Algorithm used for the signature of client's certificate</td></tr>
84 <tr><td><code>SSL_CLIENT_A_KEY</code></td> <td>string</td> <td>Algorithm used for the public key of client's certificate</td></tr>
85 <tr><td><code>SSL_CLIENT_CERT</code></td> <td>string</td> <td>PEM-encoded client certificate</td></tr>
86 <tr><td><code>SSL_CLIENT_CERT_CHAIN_</code><em>n</em></td> <td>string</td> <td>PEM-encoded certificates in client certificate chain</td></tr>
87 <tr><td><code>SSL_CLIENT_VERIFY</code></td> <td>string</td> <td><code>NONE</code>, <code>SUCCESS</code>, <code>GENEROUS</code> or <code>FAILED:</code><em>reason</em></td></tr>
88 <tr><td><code>SSL_SERVER_M_VERSION</code></td> <td>string</td> <td>The version of the server certificate</td></tr>
89 <tr><td><code>SSL_SERVER_M_SERIAL</code></td> <td>string</td> <td>The serial of the server certificate</td></tr>
90 <tr><td><code>SSL_SERVER_S_DN</code></td> <td>string</td> <td>Subject DN in server's certificate</td></tr>
91 <tr><td><code>SSL_SERVER_S_DN_</code><em>x509</em></td> <td>string</td> <td>Component of server's Subject DN</td></tr>
92 <tr><td><code>SSL_SERVER_I_DN</code></td> <td>string</td> <td>Issuer DN of server's certificate</td></tr>
93 <tr><td><code>SSL_SERVER_I_DN_</code><em>x509</em></td> <td>string</td> <td>Component of server's Issuer DN</td></tr>
94 <tr><td><code>SSL_SERVER_V_START</code></td> <td>string</td> <td>Validity of server's certificate (start time)</td></tr>
95 <tr><td><code>SSL_SERVER_V_END</code></td> <td>string</td> <td>Validity of server's certificate (end time)</td></tr>
96 <tr><td><code>SSL_SERVER_A_SIG</code></td> <td>string</td> <td>Algorithm used for the signature of server's certificate</td></tr>
97 <tr><td><code>SSL_SERVER_A_KEY</code></td> <td>string</td> <td>Algorithm used for the public key of server's certificate</td></tr>
98 <tr><td><code>SSL_SERVER_CERT</code></td> <td>string</td> <td>PEM-encoded server certificate</td></tr>
99 <tr><td><code>SSL_SRP_USER</code></td> <td>string</td> <td>SRP username</td></tr>
100 <tr><td><code>SSL_SRP_USERINFO</code></td> <td>string</td> <td>SRP user info</td></tr>
101 <tr><td><code>SSL_TLS_SNI</code></td> <td>string</td> <td>Contents of the SNI TLS extension (if supplied with ClientHello)</td></tr>
104 <p><em>x509</em> specifies a component of an X.509 DN; one of
105 <code>C,ST,L,O,OU,CN,T,I,G,S,D,UID,Email</code>. In Apache 2.1 and
106 later, <em>x509</em> may also include a numeric <code>_n</code>
107 suffix. If the DN in question contains multiple attributes of the
108 same name, this suffix is used as a zero-based index to select a
109 particular attribute. For example, where the server certificate
110 subject DN included two OU attributes, <code>SSL_SERVER_S_DN_OU_0</code>
112 <code>SSL_SERVER_S_DN_OU_1</code> could be used to reference each. A
113 variable name without a <code>_n</code> suffix is equivalent to that
114 name with a <code>_0</code> suffix; the first (or only) attribute.
115 When the environment table is populated using
116 the <code>StdEnvVars</code> option of
117 the <directive module="mod_ssl">SSLOptions</directive> directive, the
118 first (or only) attribute of any DN is added only under a non-suffixed
119 name; i.e. no <code>_0</code> suffixed entries are added.</p>
121 <p>The format of the <em>*_DN</em> variables has changed in Apache HTTPD
122 2.3.11. See the <code>LegacyDNStringFormat</code> option for
123 <directive module="mod_ssl">SSLOptions</directive> for details.</p>
125 <p><code>SSL_CLIENT_V_REMAIN</code> is only available in version 2.1
128 <p>A number of additional environment variables can also be used
129 in <directive>SSLRequire</directive> expressions, or in custom log
132 <note><pre>HTTP_USER_AGENT PATH_INFO AUTH_TYPE
133 HTTP_REFERER QUERY_STRING SERVER_SOFTWARE
134 HTTP_COOKIE REMOTE_HOST API_VERSION
135 HTTP_FORWARDED REMOTE_IDENT TIME_YEAR
136 HTTP_HOST IS_SUBREQ TIME_MON
137 HTTP_PROXY_CONNECTION DOCUMENT_ROOT TIME_DAY
138 HTTP_ACCEPT SERVER_ADMIN TIME_HOUR
139 THE_REQUEST SERVER_NAME TIME_MIN
140 REQUEST_FILENAME SERVER_PORT TIME_SEC
141 REQUEST_METHOD SERVER_PROTOCOL TIME_WDAY
142 REQUEST_SCHEME REMOTE_ADDR TIME
143 REQUEST_URI REMOTE_USER</pre></note>
145 <p>In these contexts, two special formats can also be used:</p>
148 <dt><code>ENV:<em>variablename</em></code></dt>
149 <dd>This will expand to the standard environment
150 variable <em>variablename</em>.</dd>
152 <dt><code>HTTP:<em>headername</em></code></dt>
153 <dd>This will expand to the value of the request header with name
154 <em>headername</em>.</dd>
159 <section id="logformats"><title>Custom Log Formats</title>
161 <p>When <module>mod_ssl</module> is built into Apache or at least
162 loaded (under DSO situation) additional functions exist for the <a
163 href="mod_log_config.html#formats">Custom Log Format</a> of
164 <module>mod_log_config</module>. First there is an
165 additional ``<code>%{</code><em>varname</em><code>}x</code>''
166 eXtension format function which can be used to expand any variables
167 provided by any module, especially those provided by mod_ssl which can
168 you find in the above table.</p>
170 For backward compatibility there is additionally a special
171 ``<code>%{</code><em>name</em><code>}c</code>'' cryptography format function
172 provided. Information about this function is provided in the <a
173 href="../ssl/ssl_compat.html">Compatibility</a> chapter.</p>
174 <example><title>Example</title>
175 <highlight language="config">
176 CustomLog logs/ssl_request_log "%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"
181 <section id="notes"><title>Request Notes</title>
183 <p><module>mod_ssl</module> sets "notes" for the request which can be
184 used in logging with the <code>%{<em>name</em>}n</code> format
185 string in <module>mod_log_config</module>.</p>
187 <p>The notes supported are as follows:</p>
190 <dt><code>ssl-access-forbidden</code></dt>
191 <dd>This note is set to the value <code>1</code> if access was
192 denied due to an <directive>SSLRequire</directive>
193 or <directive>SSLRequireSSL</directive> directive.</dd>
195 <dt><code>ssl-secure-reneg</code></dt>
196 <dd>If <module>mod_ssl</module> is built against a version of
197 OpenSSL which supports the secure renegotiation extension, this note
198 is set to the value <code>1</code> if SSL is in used for the current
199 connection, and the client also supports the secure renegotiation
200 extension. If the client does not support the secure renegotiation
201 extension, the note is set to the value <code>0</code>.
202 If <module>mod_ssl</module> is not built against a version of
203 OpenSSL which supports secure renegotiation, or if SSL is not in use
204 for the current connection, the note is not set.</dd>
209 <section id="authzproviders"><title>Authorization providers for use with Require</title>
211 <p><module>mod_ssl</module> provides a few authentication providers for use
212 with <module>mod_authz_core</module>'s
213 <directive module="mod_authz_core">Require</directive> directive.</p>
215 <section id="reqssl"><title>Require ssl</title>
217 <p>The <code>ssl</code> provider denies access if a connection is not
218 encrypted with SSL. This is similar to the
219 <directive>SSLRequireSSL</directive> directive.</p>
221 <highlight language="config">
227 <section id="reqverifyclient"><title>Require ssl-verify-client</title>
229 <p>The <code>ssl</code> provider allows access if the user is
230 authenticated with a valid client certificate. This is only
231 useful if <code>SSLVerifyClient optional</code> is in effect.</p>
233 <p>The following example grants access if the user is authenticated
234 either with a client certificate or by username and password.</p>
236 <highlight language="config">
237 Require ssl-verify-client<br/>
246 <name>SSLPassPhraseDialog</name>
247 <description>Type of pass phrase dialog for encrypted private
249 <syntax>SSLPassPhraseDialog <em>type</em></syntax>
250 <default>SSLPassPhraseDialog builtin</default>
251 <contextlist><context>server config</context></contextlist>
255 When Apache starts up it has to read the various Certificate (see
256 <directive module="mod_ssl">SSLCertificateFile</directive>) and
257 Private Key (see <directive
258 module="mod_ssl">SSLCertificateKeyFile</directive>) files of the
259 SSL-enabled virtual servers. Because for security reasons the Private
260 Key files are usually encrypted, mod_ssl needs to query the
261 administrator for a Pass Phrase in order to decrypt those files. This
262 query can be done in two ways which can be configured by
265 <li><code>builtin</code>
267 This is the default where an interactive terminal dialog occurs at startup
268 time just before Apache detaches from the terminal. Here the administrator
269 has to manually enter the Pass Phrase for each encrypted Private Key file.
270 Because a lot of SSL-enabled virtual hosts can be configured, the
271 following reuse-scheme is used to minimize the dialog: When a Private Key
272 file is encrypted, all known Pass Phrases (at the beginning there are
273 none, of course) are tried. If one of those known Pass Phrases succeeds no
274 dialog pops up for this particular Private Key file. If none succeeded,
275 another Pass Phrase is queried on the terminal and remembered for the next
276 round (where it perhaps can be reused).</p>
278 This scheme allows mod_ssl to be maximally flexible (because for N encrypted
279 Private Key files you <em>can</em> use N different Pass Phrases - but then
280 you have to enter all of them, of course) while minimizing the terminal
281 dialog (i.e. when you use a single Pass Phrase for all N Private Key files
282 this Pass Phrase is queried only once).</p></li>
284 <li><code>|/path/to/program [args...]</code>
286 <p>This mode allows an external program to be used which acts as a
287 pipe to a particular input device; the program is sent the standard
288 prompt text used for the <code>builtin</code> mode on
289 <code>stdin</code>, and is expected to write password strings on
290 <code>stdout</code>. If several passwords are needed (or an
291 incorrect password is entered), additional prompt text will be
292 written subsequent to the first password being returned, and more
293 passwords must then be written back.</p></li>
295 <li><code>exec:/path/to/program</code>
297 Here an external program is configured which is called at startup for each
298 encrypted Private Key file. It is called with one argument, a string of the
299 form ``<code>servername:portnumber:index</code>'' (with <code>index</code>
300 being a zero-based sequence number), which indicates for which server,
301 TCP port and certificate number it has to print the corresponding
302 Pass Phrase to <code>stdout</code>. The intent is that this external
303 program first runs security checks to make sure that the system is not
304 compromised by an attacker, and only when these checks were passed
305 successfully it provides the Pass Phrase.</p>
307 Both these security checks, and the way the Pass Phrase is determined, can
308 be as complex as you like. Mod_ssl just defines the interface: an
309 executable program which provides the Pass Phrase on <code>stdout</code>.
310 Nothing more or less! So, if you're really paranoid about security, here
311 is your interface. Anything else has to be left as an exercise to the
312 administrator, because local security requirements are so different.</p>
314 The reuse-algorithm above is used here, too. In other words: The external
315 program is called only once per unique Pass Phrase.</p></li>
317 <example><title>Example</title>
318 <highlight language="config">
319 SSLPassPhraseDialog exec:/usr/local/apache/sbin/pp-filter
326 <name>SSLRandomSeed</name>
327 <description>Pseudo Random Number Generator (PRNG) seeding
329 <syntax>SSLRandomSeed <em>context</em> <em>source</em>
330 [<em>bytes</em>]</syntax>
331 <contextlist><context>server config</context></contextlist>
335 This configures one or more sources for seeding the Pseudo Random Number
336 Generator (PRNG) in OpenSSL at startup time (<em>context</em> is
337 <code>startup</code>) and/or just before a new SSL connection is established
338 (<em>context</em> is <code>connect</code>). This directive can only be used
339 in the global server context because the PRNG is a global facility.</p>
341 The following <em>source</em> variants are available:</p>
343 <li><code>builtin</code>
344 <p> This is the always available builtin seeding source. Its usage
345 consumes minimum CPU cycles under runtime and hence can be always used
346 without drawbacks. The source used for seeding the PRNG contains of the
347 current time, the current process id and (when applicable) a randomly
348 chosen 1KB extract of the inter-process scoreboard structure of Apache.
349 The drawback is that this is not really a strong source and at startup
350 time (where the scoreboard is still not available) this source just
351 produces a few bytes of entropy. So you should always, at least for the
352 startup, use an additional seeding source.</p></li>
353 <li><code>file:/path/to/source</code>
355 This variant uses an external file <code>/path/to/source</code> as the
356 source for seeding the PRNG. When <em>bytes</em> is specified, only the
357 first <em>bytes</em> number of bytes of the file form the entropy (and
358 <em>bytes</em> is given to <code>/path/to/source</code> as the first
359 argument). When <em>bytes</em> is not specified the whole file forms the
360 entropy (and <code>0</code> is given to <code>/path/to/source</code> as
361 the first argument). Use this especially at startup time, for instance
362 with an available <code>/dev/random</code> and/or
363 <code>/dev/urandom</code> devices (which usually exist on modern Unix
364 derivatives like FreeBSD and Linux).</p>
366 <em>But be careful</em>: Usually <code>/dev/random</code> provides only as
367 much entropy data as it actually has, i.e. when you request 512 bytes of
368 entropy, but the device currently has only 100 bytes available two things
369 can happen: On some platforms you receive only the 100 bytes while on
370 other platforms the read blocks until enough bytes are available (which
371 can take a long time). Here using an existing <code>/dev/urandom</code> is
372 better, because it never blocks and actually gives the amount of requested
373 data. The drawback is just that the quality of the received data may not
374 be the best.</p></li>
376 <li><code>exec:/path/to/program</code>
378 This variant uses an external executable
379 <code>/path/to/program</code> as the source for seeding the
380 PRNG. When <em>bytes</em> is specified, only the first
381 <em>bytes</em> number of bytes of its <code>stdout</code> contents
382 form the entropy. When <em>bytes</em> is not specified, the
383 entirety of the data produced on <code>stdout</code> form the
384 entropy. Use this only at startup time when you need a very strong
385 seeding with the help of an external program (for instance as in
386 the example above with the <code>truerand</code> utility you can
387 find in the mod_ssl distribution which is based on the AT&T
388 <em>truerand</em> library). Using this in the connection context
389 slows down the server too dramatically, of course. So usually you
390 should avoid using external programs in that context.</p></li>
391 <li><code>egd:/path/to/egd-socket</code> (Unix only)
393 This variant uses the Unix domain socket of the
394 external Entropy Gathering Daemon (EGD) (see <a
395 href="http://www.lothar.com/tech/crypto/">http://www.lothar.com/tech
396 /crypto/</a>) to seed the PRNG. Use this if no random device exists
397 on your platform.</p></li>
399 <example><title>Example</title>
400 <highlight language="config">
401 SSLRandomSeed startup builtin
402 SSLRandomSeed startup file:/dev/random
403 SSLRandomSeed startup file:/dev/urandom 1024
404 SSLRandomSeed startup exec:/usr/local/bin/truerand 16
405 SSLRandomSeed connect builtin
406 SSLRandomSeed connect file:/dev/random
407 SSLRandomSeed connect file:/dev/urandom 1024
414 <name>SSLSessionCache</name>
415 <description>Type of the global/inter-process SSL Session
417 <syntax>SSLSessionCache <em>type</em></syntax>
418 <default>SSLSessionCache none</default>
419 <contextlist><context>server config</context></contextlist>
423 This configures the storage type of the global/inter-process SSL Session
424 Cache. This cache is an optional facility which speeds up parallel request
425 processing. For requests to the same server process (via HTTP keep-alive),
426 OpenSSL already caches the SSL session information locally. But because modern
427 clients request inlined images and other data via parallel requests (usually
428 up to four parallel requests are common) those requests are served by
429 <em>different</em> pre-forked server processes. Here an inter-process cache
430 helps to avoid unnecessary session handshakes.</p>
432 The following five storage <em>type</em>s are currently supported:</p>
434 <li><code>none</code>
436 <p>This disables the global/inter-process Session Cache. This
437 will incur a noticeable speed penalty and may cause problems if
438 using certain browsers, particularly if client certificates are
439 enabled. This setting is not recommended.</p></li>
441 <li><code>nonenotnull</code>
443 <p>This disables any global/inter-process Session Cache. However
444 it does force OpenSSL to send a non-null session ID to
445 accommodate buggy clients that require one.</p></li>
447 <li><code>dbm:/path/to/datafile</code>
449 <p>This makes use of a DBM hashfile on the local disk to
450 synchronize the local OpenSSL memory caches of the server
451 processes. This session cache may suffer reliability issues under
452 high load. To use this, ensure that
453 <module>mod_socache_dbm</module> is loaded.</p></li>
455 <li><code>shmcb:/path/to/datafile</code>[<code>(</code><em>size</em><code>)</code>]
457 <p>This makes use of a high-performance cyclic buffer
458 (approx. <em>size</em> bytes in size) inside a shared memory
459 segment in RAM (established via <code>/path/to/datafile</code>) to
460 synchronize the local OpenSSL memory caches of the server
461 processes. This is the recommended session cache. To use this,
462 ensure that <module>mod_socache_shmcb</module> is loaded.</p></li>
464 <li><code>dc:UNIX:/path/to/socket</code>
466 <p>This makes use of the <a
467 href="http://www.distcache.org/">distcache</a> distributed session
468 caching libraries. The argument should specify the location of
469 the server or proxy to be used using the distcache address syntax;
470 for example, <code>UNIX:/path/to/socket</code> specifies a UNIX
471 domain socket (typically a local dc_client proxy);
472 <code>IP:server.example.com:9001</code> specifies an IP
473 address. To use this, ensure that
474 <module>mod_socache_dc</module> is loaded.</p></li>
478 <example><title>Examples</title>
479 <highlight language="config">
480 SSLSessionCache dbm:/usr/local/apache/logs/ssl_gcache_data
481 SSLSessionCache shmcb:/usr/local/apache/logs/ssl_gcache_data(512000)
485 <p>The <code>ssl-cache</code> mutex is used to serialize access to
486 the session cache to prevent corruption. This mutex can be configured
487 using the <directive module="core">Mutex</directive> directive.</p>
492 <name>SSLSessionCacheTimeout</name>
493 <description>Number of seconds before an SSL session expires
494 in the Session Cache</description>
495 <syntax>SSLSessionCacheTimeout <em>seconds</em></syntax>
496 <default>SSLSessionCacheTimeout 300</default>
497 <contextlist><context>server config</context>
498 <context>virtual host</context></contextlist>
502 This directive sets the timeout in seconds for the information stored in the
503 global/inter-process SSL Session Cache, the OpenSSL internal memory cache and
504 for sessions resumed by TLS session resumption (RFC 5077).
505 It can be set as low as 15 for testing, but should be set to higher
506 values like 300 in real life.</p>
507 <example><title>Example</title>
508 <highlight language="config">
509 SSLSessionCacheTimeout 600
516 <name>SSLEngine</name>
517 <description>SSL Engine Operation Switch</description>
518 <syntax>SSLEngine on|off|optional</syntax>
519 <default>SSLEngine off</default>
520 <contextlist><context>server config</context>
521 <context>virtual host</context></contextlist>
525 This directive toggles the usage of the SSL/TLS Protocol Engine. This
526 is should be used inside a <directive module="core"
527 type="section">VirtualHost</directive> section to enable SSL/TLS for a
528 that virtual host. By default the SSL/TLS Protocol Engine is
529 disabled for both the main server and all configured virtual hosts.</p>
530 <example><title>Example</title>
531 <highlight language="config">
532 <VirtualHost _default_:443>
538 <p>In Apache 2.1 and later, <directive>SSLEngine</directive> can be set to
539 <code>optional</code>. This enables support for
540 <a href="http://www.ietf.org/rfc/rfc2817.txt">RFC 2817</a>, Upgrading to TLS
541 Within HTTP/1.1. At this time no web browsers support RFC 2817.</p>
547 <description>SSL FIPS mode Switch</description>
548 <syntax>SSLFIPS on|off</syntax>
549 <default>SSLFIPS off</default>
550 <contextlist><context>server config</context></contextlist>
554 This directive toggles the usage of the SSL library FIPS_mode flag.
555 It must be set in the global server context and cannot be configured
556 with conflicting settings (SSLFIPS on followed by SSLFIPS off or
557 similar). The mode applies to all SSL library operations.
560 If httpd was compiled against an SSL library which did not support
561 the FIPS_mode flag, <code>SSLFIPS on</code> will fail. Refer to the
562 FIPS 140-2 Security Policy document of the SSL provider library for
563 specific requirements to use mod_ssl in a FIPS 140-2 approved mode
564 of operation; note that mod_ssl itself is not validated, but may be
565 described as using FIPS 140-2 validated cryptographic module, when
566 all components are assembled and operated under the guidelines imposed
567 by the applicable Security Policy.
573 <name>SSLProtocol</name>
574 <description>Configure usable SSL/TLS protocol versions</description>
575 <syntax>SSLProtocol [+|-]<em>protocol</em> ...</syntax>
576 <default>SSLProtocol all</default>
577 <contextlist><context>server config</context>
578 <context>virtual host</context></contextlist>
582 This directive can be used to control which versions of the SSL/TLS protocol
583 will be accepted in new connections.</p>
585 The available (case-insensitive) <em>protocol</em>s are:</p>
587 <li><code>SSLv3</code>
589 This is the Secure Sockets Layer (SSL) protocol, version 3.0, from
590 the Netscape Corporation.
591 It is the successor to SSLv2 and the predecessor to TLSv1.</p></li>
593 <li><code>TLSv1</code>
595 This is the Transport Layer Security (TLS) protocol, version 1.0.
596 It is the successor to SSLv3 and is defined in
597 <a href="http://www.ietf.org/rfc/rfc2246.txt">RFC 2246</a>.
598 It is supported by nearly every client.</p></li>
600 <li><code>TLSv1.1</code> (when using OpenSSL 1.0.1 and later)
602 A revision of the TLS 1.0 protocol, as defined in
603 <a href="http://www.ietf.org/rfc/rfc4346.txt">RFC 4346</a>.</p></li>
605 <li><code>TLSv1.2</code> (when using OpenSSL 1.0.1 and later)
607 A revision of the TLS 1.1 protocol, as defined in
608 <a href="http://www.ietf.org/rfc/rfc5246.txt">RFC 5246</a>.</p></li>
612 This is a shortcut for ``<code>+SSLv3 +TLSv1</code>'' or
613 - when using OpenSSL 1.0.1 and later -
614 ``<code>+SSLv3 +TLSv1 +TLSv1.1 +TLSv1.2</code>, respectively.</p></li>
616 <example><title>Example</title>
617 <highlight language="config">
625 <name>SSLCipherSuite</name>
626 <description>Cipher Suite available for negotiation in SSL
627 handshake</description>
628 <syntax>SSLCipherSuite <em>cipher-spec</em></syntax>
629 <default>SSLCipherSuite DEFAULT (depends on OpenSSL version)</default>
630 <contextlist><context>server config</context>
631 <context>virtual host</context>
632 <context>directory</context>
633 <context>.htaccess</context></contextlist>
634 <override>AuthConfig</override>
638 This complex directive uses a colon-separated <em>cipher-spec</em> string
639 consisting of OpenSSL cipher specifications to configure the Cipher Suite the
640 client is permitted to negotiate in the SSL handshake phase. Notice that this
641 directive can be used both in per-server and per-directory context. In
642 per-server context it applies to the standard SSL handshake when a connection
643 is established. In per-directory context it forces a SSL renegotiation with the
644 reconfigured Cipher Suite after the HTTP request was read but before the HTTP
645 response is sent.</p>
647 An SSL cipher specification in <em>cipher-spec</em> is composed of 4 major
648 attributes plus a few extra minor ones:</p>
650 <li><em>Key Exchange Algorithm</em>:<br />
651 RSA, Diffie-Hellman, Elliptic Curve Diffie-Hellman, Secure Remote Password
653 <li><em>Authentication Algorithm</em>:<br />
654 RSA, Diffie-Hellman, DSS, ECDSA, or none.
656 <li><em>Cipher/Encryption Algorithm</em>:<br />
657 AES, DES, Triple-DES, RC4, RC2, IDEA, etc.
659 <li><em>MAC Digest Algorithm</em>:<br />
660 MD5, SHA or SHA1, SHA256, SHA384.
663 <p>An SSL cipher can also be an export cipher. SSLv2 ciphers are no longer
664 supported. To specify which ciphers to use, one can either specify all the
665 Ciphers, one at a time, or use aliases to specify the preference and order
666 for the ciphers (see <a href="#table1">Table
667 1</a>). The actually available ciphers and aliases depends on the used
668 openssl version. Newer openssl versions may include additional ciphers.</p>
671 <columnspec><column width=".5"/><column width=".5"/></columnspec>
672 <tr><th><a name="table1">Tag</a></th> <th>Description</th></tr>
673 <tr><td colspan="2"><em>Key Exchange Algorithm:</em></td></tr>
674 <tr><td><code>kRSA</code></td> <td>RSA key exchange</td></tr>
675 <tr><td><code>kDHr</code></td> <td>Diffie-Hellman key exchange with RSA key</td></tr>
676 <tr><td><code>kDHd</code></td> <td>Diffie-Hellman key exchange with DSA key</td></tr>
677 <tr><td><code>kEDH</code></td> <td>Ephemeral (temp.key) Diffie-Hellman key exchange (no cert)</td> </tr>
678 <tr><td><code>kSRP</code></td> <td>Secure Remote Password (SRP) key exchange</td></tr>
679 <tr><td colspan="2"><em>Authentication Algorithm:</em></td></tr>
680 <tr><td><code>aNULL</code></td> <td>No authentication</td></tr>
681 <tr><td><code>aRSA</code></td> <td>RSA authentication</td></tr>
682 <tr><td><code>aDSS</code></td> <td>DSS authentication</td> </tr>
683 <tr><td><code>aDH</code></td> <td>Diffie-Hellman authentication</td></tr>
684 <tr><td colspan="2"><em>Cipher Encoding Algorithm:</em></td></tr>
685 <tr><td><code>eNULL</code></td> <td>No encryption</td> </tr>
686 <tr><td><code>NULL</code></td> <td>alias for eNULL</td> </tr>
687 <tr><td><code>AES</code></td> <td>AES encryption</td> </tr>
688 <tr><td><code>DES</code></td> <td>DES encryption</td> </tr>
689 <tr><td><code>3DES</code></td> <td>Triple-DES encryption</td> </tr>
690 <tr><td><code>RC4</code></td> <td>RC4 encryption</td> </tr>
691 <tr><td><code>RC2</code></td> <td>RC2 encryption</td> </tr>
692 <tr><td><code>IDEA</code></td> <td>IDEA encryption</td> </tr>
693 <tr><td colspan="2"><em>MAC Digest Algorithm</em>:</td></tr>
694 <tr><td><code>MD5</code></td> <td>MD5 hash function</td></tr>
695 <tr><td><code>SHA1</code></td> <td>SHA1 hash function</td></tr>
696 <tr><td><code>SHA</code></td> <td>alias for SHA1</td> </tr>
697 <tr><td><code>SHA256</code></td> <td>SHA256 hash function</td> </tr>
698 <tr><td><code>SHA384</code></td> <td>SHA384 hash function</td> </tr>
699 <tr><td colspan="2"><em>Aliases:</em></td></tr>
700 <tr><td><code>SSLv3</code></td> <td>all SSL version 3.0 ciphers</td> </tr>
701 <tr><td><code>TLSv1</code></td> <td>all TLS version 1.0 ciphers</td> </tr>
702 <tr><td><code>EXP</code></td> <td>all export ciphers</td> </tr>
703 <tr><td><code>EXPORT40</code></td> <td>all 40-bit export ciphers only</td> </tr>
704 <tr><td><code>EXPORT56</code></td> <td>all 56-bit export ciphers only</td> </tr>
705 <tr><td><code>LOW</code></td> <td>all low strength ciphers (no export, single DES)</td></tr>
706 <tr><td><code>MEDIUM</code></td> <td>all ciphers with 128 bit encryption</td> </tr>
707 <tr><td><code>HIGH</code></td> <td>all ciphers using Triple-DES</td> </tr>
708 <tr><td><code>RSA</code></td> <td>all ciphers using RSA key exchange</td> </tr>
709 <tr><td><code>DH</code></td> <td>all ciphers using Diffie-Hellman key exchange</td> </tr>
710 <tr><td><code>EDH</code></td> <td>all ciphers using Ephemeral Diffie-Hellman key exchange</td> </tr>
711 <tr><td><code>ECDH</code></td> <td>Elliptic Curve Diffie-Hellman key exchange</td> </tr>
712 <tr><td><code>ADH</code></td> <td>all ciphers using Anonymous Diffie-Hellman key exchange</td> </tr>
713 <tr><td><code>AECDH</code></td> <td>all ciphers using Anonymous Elliptic Curve Diffie-Hellman key exchange</td> </tr>
714 <tr><td><code>SRP</code></td> <td>all ciphers using Secure Remote Password (SRP) key exchange</td> </tr>
715 <tr><td><code>DSS</code></td> <td>all ciphers using DSS authentication</td> </tr>
716 <tr><td><code>ECDSA</code></td> <td>all ciphers using ECDSA authentication</td> </tr>
717 <tr><td><code>aNULL</code></td> <td>all ciphers using no authentication</td> </tr>
720 Now where this becomes interesting is that these can be put together
721 to specify the order and ciphers you wish to use. To speed this up
722 there are also aliases (<code>SSLv3, TLSv1, EXP, LOW, MEDIUM,
723 HIGH</code>) for certain groups of ciphers. These tags can be joined
724 together with prefixes to form the <em>cipher-spec</em>. Available
727 <li>none: add cipher to list</li>
728 <li><code>+</code>: move matching ciphers to the current location in list</li>
729 <li><code>-</code>: remove cipher from list (can be added later again)</li>
730 <li><code>!</code>: kill cipher from list completely (can <strong>not</strong> be added later again)</li>
734 <title><code>aNULL</code>, <code>eNULL</code> and <code>EXP</code>
735 ciphers are always disabled</title>
736 <p>Beginning with version 2.5.0-dev as of 2013-09-25, null and export-grade
737 ciphers are always disabled, as mod_ssl unconditionally prepends any supplied
738 cipher suite string with <code>!aNULL:!eNULL:!EXP:</code> at initialization.</p>
741 <p>A simpler way to look at all of this is to use the ``<code>openssl ciphers
742 -v</code>'' command which provides a nice way to successively create the
743 correct <em>cipher-spec</em> string. The default <em>cipher-spec</em> string
744 depends on the version of the OpenSSL libraries used. Let's suppose it is
745 ``<code>RC4-SHA:AES128-SHA:HIGH:MEDIUM:!aNULL:!MD5</code>'' which
746 means the following: Put <code>RC4-SHA</code> and <code>AES128-SHA</code> at
747 the beginning. We do this, because these ciphers offer a good compromise
748 between speed and security. Next, include high and medium security ciphers.
749 Finally, remove all ciphers which do not authenticate, i.e. for SSL the
750 Anonymous Diffie-Hellman ciphers, as well as all ciphers which use
751 <code>MD5</code> as hash algorithm, because it has been proven insufficient.</p>
754 $ openssl ciphers -v 'RC4-SHA:AES128-SHA:HIGH:MEDIUM:!aNULL:!MD5'
755 RC4-SHA SSLv3 Kx=RSA Au=RSA Enc=RC4(128) Mac=SHA1
756 AES128-SHA SSLv3 Kx=RSA Au=RSA Enc=AES(128) Mac=SHA1
757 DHE-RSA-AES256-SHA SSLv3 Kx=DH Au=RSA Enc=AES(256) Mac=SHA1
759 SEED-SHA SSLv3 Kx=RSA Au=RSA Enc=SEED(128) Mac=SHA1
760 PSK-RC4-SHA SSLv3 Kx=PSK Au=PSK Enc=RC4(128) Mac=SHA1
761 KRB5-RC4-SHA SSLv3 Kx=KRB5 Au=KRB5 Enc=RC4(128) Mac=SHA1
764 <p>The complete list of particular RSA & DH ciphers for SSL is given in <a
765 href="#table2">Table 2</a>.</p>
766 <example><title>Example</title>
767 <highlight language="config">
768 SSLCipherSuite RSA:!EXP:!NULL:+HIGH:+MEDIUM:-LOW
772 <columnspec><column width=".3"/><column width=".1"/><column width=".13"/>
773 <column width=".1"/><column width=".13"/><column width=".1"/>
774 <column width=".13"/></columnspec>
775 <tr><th><a name="table2">Cipher-Tag</a></th> <th>Protocol</th> <th>Key Ex.</th> <th>Auth.</th> <th>Enc.</th> <th>MAC</th> <th>Type</th> </tr>
776 <tr><td colspan="7"><em>RSA Ciphers:</em></td></tr>
777 <tr><td><code>DES-CBC3-SHA</code></td> <td>SSLv3</td> <td>RSA</td> <td>RSA</td> <td>3DES(168)</td> <td>SHA1</td> <td></td> </tr>
778 <tr><td><code>IDEA-CBC-SHA</code></td> <td>SSLv3</td> <td>RSA</td> <td>RSA</td> <td>IDEA(128)</td> <td>SHA1</td> <td></td> </tr>
779 <tr><td><code>RC4-SHA</code></td> <td>SSLv3</td> <td>RSA</td> <td>RSA</td> <td>RC4(128)</td> <td>SHA1</td> <td></td> </tr>
780 <tr><td><code>RC4-MD5</code></td> <td>SSLv3</td> <td>RSA</td> <td>RSA</td> <td>RC4(128)</td> <td>MD5</td> <td></td> </tr>
781 <tr><td><code>DES-CBC-SHA</code></td> <td>SSLv3</td> <td>RSA</td> <td>RSA</td> <td>DES(56)</td> <td>SHA1</td> <td></td> </tr>
782 <tr><td><code>EXP-DES-CBC-SHA</code></td> <td>SSLv3</td> <td>RSA(512)</td> <td>RSA</td> <td>DES(40)</td> <td>SHA1</td> <td> export</td> </tr>
783 <tr><td><code>EXP-RC2-CBC-MD5</code></td> <td>SSLv3</td> <td>RSA(512)</td> <td>RSA</td> <td>RC2(40)</td> <td>MD5</td> <td> export</td> </tr>
784 <tr><td><code>EXP-RC4-MD5</code></td> <td>SSLv3</td> <td>RSA(512)</td> <td>RSA</td> <td>RC4(40)</td> <td>MD5</td> <td> export</td> </tr>
785 <tr><td><code>NULL-SHA</code></td> <td>SSLv3</td> <td>RSA</td> <td>RSA</td> <td>None</td> <td>SHA1</td> <td></td> </tr>
786 <tr><td><code>NULL-MD5</code></td> <td>SSLv3</td> <td>RSA</td> <td>RSA</td> <td>None</td> <td>MD5</td> <td></td> </tr>
787 <tr><td colspan="7"><em>Diffie-Hellman Ciphers:</em></td></tr>
788 <tr><td><code>ADH-DES-CBC3-SHA</code></td> <td>SSLv3</td> <td>DH</td> <td>None</td> <td>3DES(168)</td> <td>SHA1</td> <td></td> </tr>
789 <tr><td><code>ADH-DES-CBC-SHA</code></td> <td>SSLv3</td> <td>DH</td> <td>None</td> <td>DES(56)</td> <td>SHA1</td> <td></td> </tr>
790 <tr><td><code>ADH-RC4-MD5</code></td> <td>SSLv3</td> <td>DH</td> <td>None</td> <td>RC4(128)</td> <td>MD5</td> <td></td> </tr>
791 <tr><td><code>EDH-RSA-DES-CBC3-SHA</code></td> <td>SSLv3</td> <td>DH</td> <td>RSA</td> <td>3DES(168)</td> <td>SHA1</td> <td></td> </tr>
792 <tr><td><code>EDH-DSS-DES-CBC3-SHA</code></td> <td>SSLv3</td> <td>DH</td> <td>DSS</td> <td>3DES(168)</td> <td>SHA1</td> <td></td> </tr>
793 <tr><td><code>EDH-RSA-DES-CBC-SHA</code></td> <td>SSLv3</td> <td>DH</td> <td>RSA</td> <td>DES(56)</td> <td>SHA1</td> <td></td> </tr>
794 <tr><td><code>EDH-DSS-DES-CBC-SHA</code></td> <td>SSLv3</td> <td>DH</td> <td>DSS</td> <td>DES(56)</td> <td>SHA1</td> <td></td> </tr>
795 <tr><td><code>EXP-EDH-RSA-DES-CBC-SHA</code></td> <td>SSLv3</td> <td>DH(512)</td> <td>RSA</td> <td>DES(40)</td> <td>SHA1</td> <td> export</td> </tr>
796 <tr><td><code>EXP-EDH-DSS-DES-CBC-SHA</code></td> <td>SSLv3</td> <td>DH(512)</td> <td>DSS</td> <td>DES(40)</td> <td>SHA1</td> <td> export</td> </tr>
797 <tr><td><code>EXP-ADH-DES-CBC-SHA</code></td> <td>SSLv3</td> <td>DH(512)</td> <td>None</td> <td>DES(40)</td> <td>SHA1</td> <td> export</td> </tr>
798 <tr><td><code>EXP-ADH-RC4-MD5</code></td> <td>SSLv3</td> <td>DH(512)</td> <td>None</td> <td>RC4(40)</td> <td>MD5</td> <td> export</td> </tr>
804 <name>SSLCertificateFile</name>
805 <description>Server PEM-encoded X.509 certificate data file</description>
806 <syntax>SSLCertificateFile <em>file-path</em></syntax>
807 <contextlist><context>server config</context>
808 <context>virtual host</context></contextlist>
812 This directive points to a file with certificate data in PEM format.
813 At a minimum, the file must include an end-entity (leaf) certificate.
814 Beginning with version 2.5.0-dev as of 2013-12-28, it may also
815 include intermediate CA certificates, sorted from leaf to root,
816 and obsoletes <directive module="mod_ssl">SSLCertificateChainFile</directive>.
820 Additional optional elements are DH parameters and/or an EC curve name
821 for ephemeral keys, as generated by <code>openssl dhparam</code> and
822 <code>openssl ecparam</code>, respectively (supported in version 2.5.0-dev
823 as of 2013-09-29), and finally, the end-entity certificate's private key.
824 If the private key is encrypted, the pass phrase dialog is forced
828 This directive can be used multiple times (referencing different filenames)
829 to support multiple algorithms for server authentication - typically
830 RSA, DSA, and ECC. The number of supported algorithms depends on the
831 OpenSSL version being used for mod_ssl: with version 1.0.0 or later,
832 <code>openssl list-public-key-algorithms</code> will output a list
833 of supported algorithms.</p>
836 When running with OpenSSL 1.0.2 or later, this directive allows
837 to configure the intermediate CA chain on a per-certificate basis,
838 which removes a limitation of the (now obsolete)
839 <directive module="mod_ssl">SSLCertificateChainFile</directive> directive.
840 DH and ECDH parameters, however, are only read from the first
841 <directive>SSLCertificateFile</directive> directive, as they
842 are applied independently of the authentication algorithm type.</p>
845 <title>DH parameter interoperability with primes > 1024 bit</title>
847 Beginning with version 2.4.7, mod_ssl makes use of
848 standardized DH parameters with prime lengths of 2048, 3072 and 4096 bits
849 and with additional prime lengths of 6144 and 8192 bits beginning with
851 (from <a href="http://www.ietf.org/rfc/rfc3526.txt">RFC 3526</a>), and hands
852 them out to clients based on the length of the certificate's RSA/DSA key.
853 With Java-based clients in particular (Java 7 or earlier), this may lead
854 to handshake failures - see this
855 <a href="../ssl/ssl_faq.html#javadh">FAQ answer</a> for working around
860 <example><title>Example</title>
861 <highlight language="config">
862 SSLCertificateFile /usr/local/apache2/conf/ssl.crt/server.crt
869 <name>SSLCertificateKeyFile</name>
870 <description>Server PEM-encoded private key file</description>
871 <syntax>SSLCertificateKeyFile <em>file-path</em></syntax>
872 <contextlist><context>server config</context>
873 <context>virtual host</context></contextlist>
877 This directive points to the PEM-encoded private key file for the
878 server (the private key may also be combined with the certificate in the
879 <directive module="mod_ssl">SSLCertificateFile</directive>, but this practice
880 is discouraged). If the contained private key is encrypted, the pass phrase
881 dialog is forced at startup time.</p>
884 The directive can be used multiple times (referencing different filenames)
885 to support multiple algorithms for server authentication. For each
886 <directive module="mod_ssl">SSLCertificateKeyFile</directive>
887 directive, there must be a matching <directive>SSLCertificateFile</directive>
890 <example><title>Example</title>
891 <highlight language="config">
892 SSLCertificateKeyFile /usr/local/apache2/conf/ssl.key/server.key
899 <name>SSLCertificateChainFile</name>
900 <description>File of PEM-encoded Server CA Certificates</description>
901 <syntax>SSLCertificateChainFile <em>file-path</em></syntax>
902 <contextlist><context>server config</context>
903 <context>virtual host</context></contextlist>
906 <note><title>SSLCertificateChainFile is deprecated</title>
907 <p><code>SSLCertificateChainFile</code> became obsolete with version
908 2.5.0-dev as of 2013-12-28, when
909 <directive module="mod_ssl">SSLCertificateFile</directive>
910 was extended to also load intermediate CA certificates from the server
911 certificate file.</p>
915 This directive sets the optional <em>all-in-one</em> file where you can
916 assemble the certificates of Certification Authorities (CA) which form the
917 certificate chain of the server certificate. This starts with the issuing CA
918 certificate of the server certificate and can range up to the root CA
919 certificate. Such a file is simply the concatenation of the various
920 PEM-encoded CA Certificate files, usually in certificate chain order.</p>
922 This should be used alternatively and/or additionally to <directive
923 module="mod_ssl">SSLCACertificatePath</directive> for explicitly
924 constructing the server certificate chain which is sent to the browser
925 in addition to the server certificate. It is especially useful to
926 avoid conflicts with CA certificates when using client
927 authentication. Because although placing a CA certificate of the
928 server certificate chain into <directive
929 module="mod_ssl">SSLCACertificatePath</directive> has the same effect
930 for the certificate chain construction, it has the side-effect that
931 client certificates issued by this same CA certificate are also
932 accepted on client authentication.</p>
934 But be careful: Providing the certificate chain works only if you are using a
935 <em>single</em> RSA <em>or</em> DSA based server certificate. If you are
936 using a coupled RSA+DSA certificate pair, this will work only if actually both
937 certificates use the <em>same</em> certificate chain. Else the browsers will be
938 confused in this situation.</p>
939 <example><title>Example</title>
940 <highlight language="config">
941 SSLCertificateChainFile /usr/local/apache2/conf/ssl.crt/ca.crt
948 <name>SSLCACertificatePath</name>
949 <description>Directory of PEM-encoded CA Certificates for
950 Client Auth</description>
951 <syntax>SSLCACertificatePath <em>directory-path</em></syntax>
952 <contextlist><context>server config</context>
953 <context>virtual host</context></contextlist>
957 This directive sets the directory where you keep the Certificates of
958 Certification Authorities (CAs) whose clients you deal with. These are used to
959 verify the client certificate on Client Authentication.</p>
961 The files in this directory have to be PEM-encoded and are accessed through
962 hash filenames. So usually you can't just place the Certificate files
963 there: you also have to create symbolic links named
964 <em>hash-value</em><code>.N</code>. And you should always make sure this directory
965 contains the appropriate symbolic links.</p>
966 <example><title>Example</title>
967 <highlight language="config">
968 SSLCACertificatePath /usr/local/apache2/conf/ssl.crt/
975 <name>SSLCACertificateFile</name>
976 <description>File of concatenated PEM-encoded CA Certificates
977 for Client Auth</description>
978 <syntax>SSLCACertificateFile <em>file-path</em></syntax>
979 <contextlist><context>server config</context>
980 <context>virtual host</context></contextlist>
984 This directive sets the <em>all-in-one</em> file where you can assemble the
985 Certificates of Certification Authorities (CA) whose <em>clients</em> you deal
986 with. These are used for Client Authentication. Such a file is simply the
987 concatenation of the various PEM-encoded Certificate files, in order of
988 preference. This can be used alternatively and/or additionally to
989 <directive module="mod_ssl">SSLCACertificatePath</directive>.</p>
990 <example><title>Example</title>
991 <highlight language="config">
992 SSLCACertificateFile /usr/local/apache2/conf/ssl.crt/ca-bundle-client.crt
999 <name>SSLCADNRequestFile</name>
1000 <description>File of concatenated PEM-encoded CA Certificates
1001 for defining acceptable CA names</description>
1002 <syntax>SSLCADNRequestFile <em>file-path</em></syntax>
1003 <contextlist><context>server config</context>
1004 <context>virtual host</context></contextlist>
1007 <p>When a client certificate is requested by mod_ssl, a list of
1008 <em>acceptable Certificate Authority names</em> is sent to the client
1009 in the SSL handshake. These CA names can be used by the client to
1010 select an appropriate client certificate out of those it has
1013 <p>If neither of the directives <directive
1014 module="mod_ssl">SSLCADNRequestPath</directive> or <directive
1015 module="mod_ssl">SSLCADNRequestFile</directive> are given, then the
1016 set of acceptable CA names sent to the client is the names of all the
1017 CA certificates given by the <directive
1018 module="mod_ssl">SSLCACertificateFile</directive> and <directive
1019 module="mod_ssl">SSLCACertificatePath</directive> directives; in other
1020 words, the names of the CAs which will actually be used to verify the
1021 client certificate.</p>
1023 <p>In some circumstances, it is useful to be able to send a set of
1024 acceptable CA names which differs from the actual CAs used to verify
1025 the client certificate - for example, if the client certificates are
1026 signed by intermediate CAs. In such cases, <directive
1027 module="mod_ssl">SSLCADNRequestPath</directive> and/or <directive
1028 module="mod_ssl">SSLCADNRequestFile</directive> can be used; the
1029 acceptable CA names are then taken from the complete set of
1030 certificates in the directory and/or file specified by this pair of
1033 <p><directive module="mod_ssl">SSLCADNRequestFile</directive> must
1034 specify an <em>all-in-one</em> file containing a concatenation of
1035 PEM-encoded CA certificates.</p>
1037 <example><title>Example</title>
1038 <highlight language="config">
1039 SSLCADNRequestFile /usr/local/apache2/conf/ca-names.crt
1043 </directivesynopsis>
1046 <name>SSLCADNRequestPath</name>
1047 <description>Directory of PEM-encoded CA Certificates for
1048 defining acceptable CA names</description>
1049 <syntax>SSLCADNRequestPath <em>directory-path</em></syntax>
1050 <contextlist><context>server config</context>
1051 <context>virtual host</context></contextlist>
1055 <p>This optional directive can be used to specify the set of
1056 <em>acceptable CA names</em> which will be sent to the client when a
1057 client certificate is requested. See the <directive
1058 module="mod_ssl">SSLCADNRequestFile</directive> directive for more
1061 <p>The files in this directory have to be PEM-encoded and are accessed
1062 through hash filenames. So usually you can't just place the
1063 Certificate files there: you also have to create symbolic links named
1064 <em>hash-value</em><code>.N</code>. And you should always make sure
1065 this directory contains the appropriate symbolic links.</p>
1066 <example><title>Example</title>
1067 <highlight language="config">
1068 SSLCADNRequestPath /usr/local/apache2/conf/ca-names.crt/
1072 </directivesynopsis>
1075 <name>SSLCARevocationPath</name>
1076 <description>Directory of PEM-encoded CA CRLs for
1077 Client Auth</description>
1078 <syntax>SSLCARevocationPath <em>directory-path</em></syntax>
1079 <contextlist><context>server config</context>
1080 <context>virtual host</context></contextlist>
1084 This directive sets the directory where you keep the Certificate Revocation
1085 Lists (CRL) of Certification Authorities (CAs) whose clients you deal with.
1086 These are used to revoke the client certificate on Client Authentication.</p>
1088 The files in this directory have to be PEM-encoded and are accessed through
1089 hash filenames. So usually you have not only to place the CRL files there.
1090 Additionally you have to create symbolic links named
1091 <em>hash-value</em><code>.rN</code>. And you should always make sure this directory
1092 contains the appropriate symbolic links.</p>
1093 <example><title>Example</title>
1094 <highlight language="config">
1095 SSLCARevocationPath /usr/local/apache2/conf/ssl.crl/
1099 </directivesynopsis>
1102 <name>SSLCARevocationFile</name>
1103 <description>File of concatenated PEM-encoded CA CRLs for
1104 Client Auth</description>
1105 <syntax>SSLCARevocationFile <em>file-path</em></syntax>
1106 <contextlist><context>server config</context>
1107 <context>virtual host</context></contextlist>
1111 This directive sets the <em>all-in-one</em> file where you can
1112 assemble the Certificate Revocation Lists (CRL) of Certification
1113 Authorities (CA) whose <em>clients</em> you deal with. These are used
1114 for Client Authentication. Such a file is simply the concatenation of
1115 the various PEM-encoded CRL files, in order of preference. This can be
1116 used alternatively and/or additionally to <directive
1117 module="mod_ssl">SSLCARevocationPath</directive>.</p>
1118 <example><title>Example</title>
1119 <highlight language="config">
1120 SSLCARevocationFile /usr/local/apache2/conf/ssl.crl/ca-bundle-client.crl
1124 </directivesynopsis>
1127 <name>SSLCARevocationCheck</name>
1128 <description>Enable CRL-based revocation checking</description>
1129 <syntax>SSLCARevocationCheck chain|leaf|none</syntax>
1130 <default>SSLCARevocationCheck none</default>
1131 <contextlist><context>server config</context>
1132 <context>virtual host</context></contextlist>
1136 Enables certificate revocation list (CRL) checking. At least one of
1137 <directive module="mod_ssl">SSLCARevocationFile</directive>
1138 or <directive module="mod_ssl">SSLCARevocationPath</directive> must be
1139 configured. When set to <code>chain</code> (recommended setting),
1140 CRL checks are applied to all certificates in the chain, while setting it to
1141 <code>leaf</code> limits the checks to the end-entity cert.
1144 <title>When set to <code>chain</code> or <code>leaf</code>,
1145 CRLs <em>must</em> be available for successful validation</title>
1147 Prior to version 2.3.15, CRL checking in mod_ssl also succeeded when
1148 no CRL(s) were found in any of the locations configured with
1149 <directive module="mod_ssl">SSLCARevocationFile</directive>
1150 or <directive module="mod_ssl">SSLCARevocationPath</directive>.
1151 With the introduction of this directive, the behavior has been changed:
1152 when checking is enabled, CRLs <em>must</em> be present for the validation
1153 to succeed - otherwise it will fail with an
1154 <code>"unable to get certificate CRL"</code> error.
1157 <example><title>Example</title>
1158 <highlight language="config">
1159 SSLCARevocationCheck chain
1163 </directivesynopsis>
1166 <name>SSLVerifyClient</name>
1167 <description>Type of Client Certificate verification</description>
1168 <syntax>SSLVerifyClient <em>level</em></syntax>
1169 <default>SSLVerifyClient none</default>
1170 <contextlist><context>server config</context>
1171 <context>virtual host</context>
1172 <context>directory</context>
1173 <context>.htaccess</context></contextlist>
1174 <override>AuthConfig</override>
1178 This directive sets the Certificate verification level for the Client
1179 Authentication. Notice that this directive can be used both in per-server and
1180 per-directory context. In per-server context it applies to the client
1181 authentication process used in the standard SSL handshake when a connection is
1182 established. In per-directory context it forces a SSL renegotiation with the
1183 reconfigured client verification level after the HTTP request was read but
1184 before the HTTP response is sent.</p>
1186 The following levels are available for <em>level</em>:</p>
1188 <li><strong>none</strong>:
1189 no client Certificate is required at all</li>
1190 <li><strong>optional</strong>:
1191 the client <em>may</em> present a valid Certificate</li>
1192 <li><strong>require</strong>:
1193 the client <em>has to</em> present a valid Certificate</li>
1194 <li><strong>optional_no_ca</strong>:
1195 the client may present a valid Certificate<br />
1196 but it need not to be (successfully) verifiable.</li>
1198 <p>In practice only levels <strong>none</strong> and
1199 <strong>require</strong> are really interesting, because level
1200 <strong>optional</strong> doesn't work with all browsers and level
1201 <strong>optional_no_ca</strong> is actually against the idea of
1202 authentication (but can be used to establish SSL test pages, etc.)</p>
1203 <example><title>Example</title>
1204 <highlight language="config">
1205 SSLVerifyClient require
1209 </directivesynopsis>
1212 <name>SSLVerifyDepth</name>
1213 <description>Maximum depth of CA Certificates in Client
1214 Certificate verification</description>
1215 <syntax>SSLVerifyDepth <em>number</em></syntax>
1216 <default>SSLVerifyDepth 1</default>
1217 <contextlist><context>server config</context>
1218 <context>virtual host</context>
1219 <context>directory</context>
1220 <context>.htaccess</context></contextlist>
1221 <override>AuthConfig</override>
1225 This directive sets how deeply mod_ssl should verify before deciding that the
1226 clients don't have a valid certificate. Notice that this directive can be
1227 used both in per-server and per-directory context. In per-server context it
1228 applies to the client authentication process used in the standard SSL
1229 handshake when a connection is established. In per-directory context it forces
1230 a SSL renegotiation with the reconfigured client verification depth after the
1231 HTTP request was read but before the HTTP response is sent.</p>
1233 The depth actually is the maximum number of intermediate certificate issuers,
1234 i.e. the number of CA certificates which are max allowed to be followed while
1235 verifying the client certificate. A depth of 0 means that self-signed client
1236 certificates are accepted only, the default depth of 1 means the client
1237 certificate can be self-signed or has to be signed by a CA which is directly
1238 known to the server (i.e. the CA's certificate is under
1239 <directive module="mod_ssl">SSLCACertificatePath</directive>), etc.</p>
1240 <example><title>Example</title>
1241 <highlight language="config">
1246 </directivesynopsis>
1249 <name>SSLSRPVerifierFile</name>
1250 <description>Path to SRP verifier file</description>
1251 <syntax>SSLSRPVerifierFile <em>file-path</em></syntax>
1252 <contextlist><context>server config</context>
1253 <context>virtual host</context></contextlist>
1254 <compatibility>Available in httpd 2.4.4 and later, if using OpenSSL 1.0.1 or
1255 later</compatibility>
1260 This directive enables TLS-SRP and sets the path to the OpenSSL SRP (Secure
1261 Remote Password) verifier file containing TLS-SRP usernames, verifiers, salts,
1262 and group parameters.</p>
1263 <example><title>Example</title>
1264 SSLSRPVerifierFile "/path/to/file.srpv"
1267 The verifier file can be created with the <code>openssl</code> command line
1269 <example><title>Creating the SRP verifier file</title>
1270 openssl srp -srpvfile passwd.srpv -userinfo "some info" -add username
1272 <p> The value given with the optional <code>-userinfo</code> parameter is
1273 avalable in the <code>SSL_SRP_USERINFO</code> request environment variable.</p>
1276 </directivesynopsis>
1279 <name>SSLSRPUnknownUserSeed</name>
1280 <description>SRP unknown user seed</description>
1281 <syntax>SSLSRPUnknownUserSeed <em>secret-string</em></syntax>
1282 <contextlist><context>server config</context>
1283 <context>virtual host</context></contextlist>
1284 <compatibility>Available in httpd 2.4.4 and later, if using OpenSSL 1.0.1 or
1285 later</compatibility>
1289 This directive sets the seed used to fake SRP user parameters for unknown
1290 users, to avoid leaking whether a given user exists. Specify a secret
1291 string. If this directive is not used, then Apache will return the
1292 UNKNOWN_PSK_IDENTITY alert to clients who specify an unknown username.
1294 <example><title>Example</title>
1295 SSLSRPUnknownUserSeed "secret"
1298 </directivesynopsis>
1301 <name>SSLOptions</name>
1302 <description>Configure various SSL engine run-time options</description>
1303 <syntax>SSLOptions [+|-]<em>option</em> ...</syntax>
1304 <contextlist><context>server config</context>
1305 <context>virtual host</context>
1306 <context>directory</context>
1307 <context>.htaccess</context></contextlist>
1308 <override>Options</override>
1312 This directive can be used to control various run-time options on a
1313 per-directory basis. Normally, if multiple <code>SSLOptions</code>
1314 could apply to a directory, then the most specific one is taken
1315 completely; the options are not merged. However if <em>all</em> the
1316 options on the <code>SSLOptions</code> directive are preceded by a
1317 plus (<code>+</code>) or minus (<code>-</code>) symbol, the options
1318 are merged. Any options preceded by a <code>+</code> are added to the
1319 options currently in force, and any options preceded by a
1320 <code>-</code> are removed from the options currently in force.</p>
1322 The available <em>option</em>s are:</p>
1324 <li><code>StdEnvVars</code>
1326 When this option is enabled, the standard set of SSL related CGI/SSI
1327 environment variables are created. This per default is disabled for
1328 performance reasons, because the information extraction step is a
1329 rather expensive operation. So one usually enables this option for
1330 CGI and SSI requests only.</p>
1332 <li><code>ExportCertData</code>
1334 When this option is enabled, additional CGI/SSI environment variables are
1335 created: <code>SSL_SERVER_CERT</code>, <code>SSL_CLIENT_CERT</code> and
1336 <code>SSL_CLIENT_CERT_CHAIN_</code><em>n</em> (with <em>n</em> = 0,1,2,..).
1337 These contain the PEM-encoded X.509 Certificates of server and client for
1338 the current HTTPS connection and can be used by CGI scripts for deeper
1339 Certificate checking. Additionally all other certificates of the client
1340 certificate chain are provided, too. This bloats up the environment a
1341 little bit which is why you have to use this option to enable it on
1344 <li><code>FakeBasicAuth</code>
1346 When this option is enabled, the Subject Distinguished Name (DN) of the
1347 Client X509 Certificate is translated into a HTTP Basic Authorization
1348 username. This means that the standard Apache authentication methods can
1349 be used for access control. The user name is just the Subject of the
1350 Client's X509 Certificate (can be determined by running OpenSSL's
1351 <code>openssl x509</code> command: <code>openssl x509 -noout -subject -in
1352 </code><em>certificate</em><code>.crt</code>). The optional <directive
1353 module="mod_ssl">SSLUserName</directive> directive can be used to
1354 specify which part of the certificate Subject is embedded in the username.
1355 Note that no password is obtained from the user. Every entry in the user
1356 file needs this password: ``<code>xxj31ZMTZzkVA</code>'', which is the
1357 DES-encrypted version of the word `<code>password</code>''. Those who
1358 live under MD5-based encryption (for instance under FreeBSD or BSD/OS,
1359 etc.) should use the following MD5 hash of the same word:
1360 ``<code>$1$OXLyS...$Owx8s2/m9/gfkcRVXzgoE/</code>''.</p>
1362 <p>Note that the <directive module="mod_auth_basic">AuthBasicFake</directive>
1363 directive within <module>mod_auth_basic</module> can be used as a more
1364 general mechanism for faking basic authentication, giving control over the
1365 structure of both the username and password.</p>
1367 <li><code>StrictRequire</code>
1369 This <em>forces</em> forbidden access when <code>SSLRequireSSL</code> or
1370 <code>SSLRequire</code> successfully decided that access should be
1371 forbidden. Usually the default is that in the case where a ``<code>Satisfy
1372 any</code>'' directive is used, and other access restrictions are passed,
1373 denial of access due to <code>SSLRequireSSL</code> or
1374 <code>SSLRequire</code> is overridden (because that's how the Apache
1375 <code>Satisfy</code> mechanism should work.) But for strict access restriction
1376 you can use <code>SSLRequireSSL</code> and/or <code>SSLRequire</code> in
1377 combination with an ``<code>SSLOptions +StrictRequire</code>''. Then an
1378 additional ``<code>Satisfy Any</code>'' has no chance once mod_ssl has
1379 decided to deny access.</p>
1381 <li><code>OptRenegotiate</code>
1383 This enables optimized SSL connection renegotiation handling when SSL
1384 directives are used in per-directory context. By default a strict
1385 scheme is enabled where <em>every</em> per-directory reconfiguration of
1386 SSL parameters causes a <em>full</em> SSL renegotiation handshake. When this
1387 option is used mod_ssl tries to avoid unnecessary handshakes by doing more
1388 granular (but still safe) parameter checks. Nevertheless these granular
1389 checks sometimes may not be what the user expects, so enable this on a
1390 per-directory basis only, please.</p>
1392 <li><code>LegacyDNStringFormat</code>
1394 This option influences how values of the
1395 <code>SSL_{CLIENT,SERVER}_{I,S}_DN</code> variables are formatted. Since
1396 version 2.3.11, Apache HTTPD uses a RFC 2253 compatible format by
1397 default. This uses commas as delimiters between the attributes, allows the
1398 use of non-ASCII characters (which are converted to UTF8), escapes
1399 various special characters with backslashes, and sorts the attributes
1400 with the "C" attribute last.</p>
1402 <p>If <code>LegacyDNStringFormat</code> is set, the old format will be
1403 used which sorts the "C" attribute first, uses slashes as separators, and
1404 does not handle non-ASCII and special characters in any consistent way.
1408 <example><title>Example</title>
1409 <highlight language="config">
1410 SSLOptions +FakeBasicAuth -StrictRequire
1411 <Files ~ "\.(cgi|shtml)$">
1412 SSLOptions +StdEnvVars -ExportCertData
1417 </directivesynopsis>
1420 <name>SSLRequireSSL</name>
1421 <description>Deny access when SSL is not used for the
1422 HTTP request</description>
1423 <syntax>SSLRequireSSL</syntax>
1424 <contextlist><context>directory</context>
1425 <context>.htaccess</context></contextlist>
1426 <override>AuthConfig</override>
1429 <p><!-- XXX: I think the syntax is wrong -->
1430 This directive forbids access unless HTTP over SSL (i.e. HTTPS) is enabled for
1431 the current connection. This is very handy inside the SSL-enabled virtual
1432 host or directories for defending against configuration errors that expose
1433 stuff that should be protected. When this directive is present all requests
1434 are denied which are not using SSL.</p>
1435 <example><title>Example</title>
1436 <highlight language="config">
1441 </directivesynopsis>
1444 <name>SSLRequire</name>
1445 <description>Allow access only when an arbitrarily complex
1446 boolean expression is true</description>
1447 <syntax>SSLRequire <em>expression</em></syntax>
1448 <contextlist><context>directory</context>
1449 <context>.htaccess</context></contextlist>
1450 <override>AuthConfig</override>
1454 <note><title>SSLRequire is deprecated</title>
1455 <p><code>SSLRequire</code> is deprecated and should in general be replaced
1456 by <a href="mod_authz_core.html#reqexpr">Require expr</a>. The so called
1457 <a href="../expr.html">ap_expr</a> syntax of <code>Require expr</code> is
1458 a superset of the syntax of <code>SSLRequire</code>, with the following
1461 <p>In <code>SSLRequire</code>, the comparison operators <code><</code>,
1462 <code><=</code>, ... are completely equivalent to the operators
1463 <code>lt</code>, <code>le</code>, ... and work in a somewhat peculiar way that
1464 first compares the length of two strings and then the lexical order.
1465 On the other hand, <a href="../expr.html">ap_expr</a> has two sets of
1466 comparison operators: The operators <code><</code>,
1467 <code><=</code>, ... do lexical string comparison, while the operators
1468 <code>-lt</code>, <code>-le</code>, ... do integer comparison.
1469 For the latter, there are also aliases without the leading dashes:
1470 <code>lt</code>, <code>le</code>, ...
1476 This directive specifies a general access requirement which has to be
1477 fulfilled in order to allow access. It is a very powerful directive because the
1478 requirement specification is an arbitrarily complex boolean expression
1479 containing any number of access checks.</p>
1481 The <em>expression</em> must match the following syntax (given as a BNF
1482 grammar notation):</p>
1485 expr ::= "<strong>true</strong>" | "<strong>false</strong>"
1486 | "<strong>!</strong>" expr
1487 | expr "<strong>&&</strong>" expr
1488 | expr "<strong>||</strong>" expr
1489 | "<strong>(</strong>" expr "<strong>)</strong>"
1492 comp ::= word "<strong>==</strong>" word | word "<strong>eq</strong>" word
1493 | word "<strong>!=</strong>" word | word "<strong>ne</strong>" word
1494 | word "<strong><</strong>" word | word "<strong>lt</strong>" word
1495 | word "<strong><=</strong>" word | word "<strong>le</strong>" word
1496 | word "<strong>></strong>" word | word "<strong>gt</strong>" word
1497 | word "<strong>>=</strong>" word | word "<strong>ge</strong>" word
1498 | word "<strong>in</strong>" "<strong>{</strong>" wordlist "<strong>}</strong>"
1499 | word "<strong>in</strong>" "<strong>PeerExtList(</strong>" word "<strong>)</strong>"
1500 | word "<strong>=~</strong>" regex
1501 | word "<strong>!~</strong>" regex
1504 | wordlist "<strong>,</strong>" word
1513 variable ::= "<strong>%{</strong>" varname "<strong>}</strong>"
1514 function ::= funcname "<strong>(</strong>" funcargs "<strong>)</strong>"
1517 <p>For <code>varname</code> any of the variables described in <a
1518 href="#envvars">Environment Variables</a> can be used. For
1519 <code>funcname</code> the available functions are listed in
1520 the <a href="../expr.html#functions">ap_expr documentation</a>.</p>
1522 <p>The <em>expression</em> is parsed into an internal machine
1523 representation when the configuration is loaded, and then evaluated
1524 during request processing. In .htaccess context, the <em>expression</em> is
1525 both parsed and executed each time the .htaccess file is encountered during
1526 request processing.</p>
1528 <example><title>Example</title>
1529 <highlight language="config">
1530 SSLRequire ( %{SSL_CIPHER} !~ m/^(EXP|NULL)-/ \
1531 and %{SSL_CLIENT_S_DN_O} eq "Snake Oil, Ltd." \
1532 and %{SSL_CLIENT_S_DN_OU} in {"Staff", "CA", "Dev"} \
1533 and %{TIME_WDAY} -ge 1 and %{TIME_WDAY} -le 5 \
1534 and %{TIME_HOUR} -ge 8 and %{TIME_HOUR} -le 20 ) \
1535 or %{REMOTE_ADDR} =~ m/^192\.76\.162\.[0-9]+$/
1539 <p>The <code>PeerExtList(<em>object-ID</em>)</code> function expects
1540 to find zero or more instances of the X.509 certificate extension
1541 identified by the given <em>object ID</em> (OID) in the client certificate.
1542 The expression evaluates to true if the left-hand side string matches
1543 exactly against the value of an extension identified with this OID.
1544 (If multiple extensions with the same OID are present, at least one
1545 extension must match).</p>
1547 <example><title>Example</title>
1548 <highlight language="config">
1549 SSLRequire "foobar" in PeerExtList("1.2.3.4.5.6")
1553 <note><title>Notes on the PeerExtList function</title>
1557 <li><p>The object ID can be specified either as a descriptive
1558 name recognized by the SSL library, such as <code>"nsComment"</code>,
1559 or as a numeric OID, such as <code>"1.2.3.4.5.6"</code>.</p></li>
1561 <li><p>Expressions with types known to the SSL library are rendered to
1562 a string before comparison. For an extension with a type not
1563 recognized by the SSL library, mod_ssl will parse the value if it is
1564 one of the primitive ASN.1 types UTF8String, IA5String, VisibleString,
1565 or BMPString. For an extension of one of these types, the string
1566 value will be converted to UTF-8 if necessary, then compared against
1567 the left-hand-side expression.</p></li>
1573 <seealso><a href="../env.html">Environment Variables in Apache HTTP Server</a>,
1574 for additional examples.
1576 <seealso><a href="mod_authz_core.html#reqexpr">Require expr</a></seealso>
1577 <seealso><a href="../expr.html">Generic expression syntax in Apache HTTP Server</a>
1579 </directivesynopsis>
1582 <name>SSLRenegBufferSize</name>
1583 <description>Set the size for the SSL renegotiation buffer</description>
1584 <syntax>SSLRenegBufferSize <var>bytes</var></syntax>
1585 <default>SSLRenegBufferSize 131072</default>
1586 <contextlist><context>directory</context>
1587 <context>.htaccess</context></contextlist>
1588 <override>AuthConfig</override>
1592 <p>If an SSL renegotiation is required in per-location context, for
1593 example, any use of <directive
1594 module="mod_ssl">SSLVerifyClient</directive> in a Directory or
1595 Location block, then <module>mod_ssl</module> must buffer any HTTP
1596 request body into memory until the new SSL handshake can be performed.
1597 This directive can be used to set the amount of memory that will be
1598 used for this buffer. </p>
1600 <note type="warning"><p>
1601 Note that in many configurations, the client sending the request body
1602 will be untrusted so a denial of service attack by consumption of
1603 memory must be considered when changing this configuration setting.
1606 <example><title>Example</title>
1607 <highlight language="config">
1608 SSLRenegBufferSize 262144
1612 </directivesynopsis>
1615 <name>SSLStrictSNIVHostCheck</name>
1616 <description>Whether to allow non-SNI clients to access a name-based virtual
1619 <syntax>SSLStrictSNIVHostCheck on|off</syntax>
1620 <default>SSLStrictSNIVHostCheck off</default>
1621 <contextlist><context>server config</context>
1622 <context>virtual host</context></contextlist>
1626 This directive sets whether a non-SNI client is allowed to access a name-based
1627 virtual host. If set to <code>on</code> in the default name-based virtual
1628 host, clients that are SNI unaware will not be allowed to access <em>any</em>
1629 virtual host, belonging to this particular IP / port combination.
1630 If set to <code>on</code> in any other virtual host, SNI unaware clients
1631 are not allowed to access this particular virtual host.
1634 <note type="warning"><p>
1635 This option is only available if httpd was compiled against an SNI capable
1639 <example><title>Example</title>
1640 <highlight language="config">
1641 SSLStrictSNIVHostCheck on
1645 </directivesynopsis>
1648 <name>SSLProxyMachineCertificatePath</name>
1649 <description>Directory of PEM-encoded client certificates and keys to be used by the proxy</description>
1650 <syntax>SSLProxyMachineCertificatePath <em>directory</em></syntax>
1651 <contextlist><context>server config</context></contextlist>
1652 <override>Not applicable</override>
1656 This directive sets the directory where you keep the certificates and
1657 keys used for authentication of the proxy server to remote servers.
1659 <p>The files in this directory must be PEM-encoded and are accessed through
1660 hash filenames. Additionally, you must create symbolic links named
1661 <code><em>hash-value</em>.N</code>. And you should always make sure this
1662 directory contains the appropriate symbolic links.</p>
1663 <note type="warning">
1664 <p>Currently there is no support for encrypted private keys</p>
1666 <example><title>Example</title>
1667 <highlight language="config">
1668 SSLProxyMachineCertificatePath /usr/local/apache2/conf/proxy.crt/
1672 </directivesynopsis>
1676 <name>SSLProxyMachineCertificateFile</name>
1677 <description>File of concatenated PEM-encoded client certificates and keys to be used by the proxy</description>
1678 <syntax>SSLProxyMachineCertificateFile <em>filename</em></syntax>
1679 <contextlist><context>server config</context></contextlist>
1680 <override>Not applicable</override>
1684 This directive sets the all-in-one file where you keep the certificates and
1685 keys used for authentication of the proxy server to remote servers.
1688 This referenced file is simply the concatenation of the various PEM-encoded
1689 certificate files, in order of preference. Use this directive alternatively
1690 or additionally to <code>SSLProxyMachineCertificatePath</code>.
1692 <note type="warning">
1693 <p>Currently there is no support for encrypted private keys</p>
1695 <example><title>Example</title>
1696 <highlight language="config">
1697 SSLProxyMachineCertificateFile /usr/local/apache2/conf/ssl.crt/proxy.pem
1701 </directivesynopsis>
1704 <name>SSLProxyMachineCertificateChainFile</name>
1705 <description>File of concatenated PEM-encoded CA certificates to be used by the proxy for choosing a certificate</description>
1706 <syntax>SSLProxyMachineCertificateChainFile <em>filename</em></syntax>
1707 <contextlist><context>server config</context></contextlist>
1708 <override>Not applicable</override>
1712 This directive sets the all-in-one file where you keep the certificate chain
1713 for all of the client certs in use. This directive will be needed if the
1714 remote server presents a list of CA certificates that are not direct signers
1715 of one of the configured client certificates.
1718 This referenced file is simply the concatenation of the various PEM-encoded
1719 certificate files. Upon startup, each client certificate configured will
1720 be examined and a chain of trust will be constructed.
1722 <note type="warning"><title>Security warning</title>
1723 <p>If this directive is enabled, all of the certificates in the file will be
1724 trusted as if they were also in <directive module="mod_ssl">
1725 SSLProxyCACertificateFile</directive>.</p>
1727 <example><title>Example</title>
1728 <highlight language="config">
1729 SSLProxyMachineCertificateChainFile /usr/local/apache2/conf/ssl.crt/proxyCA.pem
1733 </directivesynopsis>
1736 <name>SSLProxyVerify</name>
1737 <description>Type of remote server Certificate verification</description>
1738 <syntax>SSLProxyVerify <em>level</em></syntax>
1739 <default>SSLProxyVerify none</default>
1740 <contextlist><context>server config</context>
1741 <context>virtual host</context> </contextlist>
1745 <p>When a proxy is configured to forward requests to a remote SSL
1746 server, this directive can be used to configure certificate
1747 verification of the remote server. </p>
1749 The following levels are available for <em>level</em>:</p>
1751 <li><strong>none</strong>:
1752 no remote server Certificate is required at all</li>
1753 <li><strong>optional</strong>:
1754 the remote server <em>may</em> present a valid Certificate</li>
1755 <li><strong>require</strong>:
1756 the remote server <em>has to</em> present a valid Certificate</li>
1757 <li><strong>optional_no_ca</strong>:
1758 the remote server may present a valid Certificate<br />
1759 but it need not to be (successfully) verifiable.</li>
1761 <p>In practice only levels <strong>none</strong> and
1762 <strong>require</strong> are really interesting, because level
1763 <strong>optional</strong> doesn't work with all servers and level
1764 <strong>optional_no_ca</strong> is actually against the idea of
1765 authentication (but can be used to establish SSL test pages, etc.)</p>
1766 <example><title>Example</title>
1767 <highlight language="config">
1768 SSLProxyVerify require
1772 </directivesynopsis>
1775 <name>SSLProxyVerifyDepth</name>
1776 <description>Maximum depth of CA Certificates in Remote Server
1777 Certificate verification</description>
1778 <syntax>SSLProxyVerifyDepth <em>number</em></syntax>
1779 <default>SSLProxyVerifyDepth 1</default>
1780 <contextlist><context>server config</context>
1781 <context>virtual host</context> </contextlist>
1785 This directive sets how deeply mod_ssl should verify before deciding that the
1786 remote server does not have a valid certificate. </p>
1788 The depth actually is the maximum number of intermediate certificate issuers,
1789 i.e. the number of CA certificates which are max allowed to be followed while
1790 verifying the remote server certificate. A depth of 0 means that self-signed
1791 remote server certificates are accepted only, the default depth of 1 means
1792 the remote server certificate can be self-signed or has to be signed by a CA
1793 which is directly known to the server (i.e. the CA's certificate is under
1794 <directive module="mod_ssl">SSLProxyCACertificatePath</directive>), etc.</p>
1795 <example><title>Example</title>
1796 <highlight language="config">
1797 SSLProxyVerifyDepth 10
1801 </directivesynopsis>
1804 <name>SSLProxyCheckPeerExpire</name>
1805 <description>Whether to check if remote server certificate is expired
1807 <syntax>SSLProxyCheckPeerExpire on|off</syntax>
1808 <default>SSLProxyCheckPeerExpire on</default>
1809 <contextlist><context>server config</context>
1810 <context>virtual host</context></contextlist>
1814 This directive sets whether it is checked if the remote server certificate
1815 is expired or not. If the check fails a 502 status code (Bad Gateway) is
1818 <example><title>Example</title>
1819 <highlight language="config">
1820 SSLProxyCheckPeerExpire on
1824 </directivesynopsis>
1827 <name>SSLProxyCheckPeerCN</name>
1828 <description>Whether to check the remote server certificate's CN field
1830 <syntax>SSLProxyCheckPeerCN on|off</syntax>
1831 <default>SSLProxyCheckPeerCN on</default>
1832 <contextlist><context>server config</context>
1833 <context>virtual host</context></contextlist>
1837 This directive sets whether the remote server certificate's CN field is
1838 compared against the hostname of the request URL. If both are not equal
1839 a 502 status code (Bad Gateway) is sent.
1842 SSLProxyCheckPeerCN has been superseded by
1843 <directive module="mod_ssl">SSLProxyCheckPeerName</directive>, and its
1844 setting is only taken into account when
1845 <code>SSLProxyCheckPeerName off</code> is specified at the same time.
1847 <example><title>Example</title>
1848 <highlight language="config">
1849 SSLProxyCheckPeerCN on
1853 </directivesynopsis>
1856 <name>SSLProxyCheckPeerName</name>
1857 <description>Configure host name checking for remote server certificates
1859 <syntax>SSLProxyCheckPeerName on|off</syntax>
1860 <default>SSLProxyCheckPeerName on</default>
1861 <contextlist><context>server config</context>
1862 <context>virtual host</context></contextlist>
1866 This directive configures host name checking for server certificates
1867 when mod_ssl is acting as an SSL client. The check will
1868 succeed if the host name from the request URI is found in
1869 either the subjectAltName extension or (one of) the CN attribute(s)
1870 in the certificate's subject. If the check fails, the SSL request
1871 is aborted and a 502 status code (Bad Gateway) is returned.
1872 The directive supersedes <directive module="mod_ssl">SSLProxyCheckPeerCN</directive>,
1873 which only checks for the expected host name in the first CN attribute.
1876 Wildcard matching is supported in one specific flavor: subjectAltName entries
1877 of type dNSName or CN attributes starting with <code>*.</code> will match
1878 for any DNS name with the same number of labels and the same suffix
1879 (i.e., <code>*.example.org</code> matches for <code>foo.example.org</code>,
1880 but not for <code>foo.bar.example.org</code>).
1883 </directivesynopsis>
1886 <name>SSLProxyEngine</name>
1887 <description>SSL Proxy Engine Operation Switch</description>
1888 <syntax>SSLProxyEngine on|off</syntax>
1889 <default>SSLProxyEngine off</default>
1890 <contextlist><context>server config</context>
1891 <context>virtual host</context></contextlist>
1895 This directive toggles the usage of the SSL/TLS Protocol Engine for proxy. This
1896 is usually used inside a <directive module="core"
1897 type="section">VirtualHost</directive> section to enable SSL/TLS for proxy
1898 usage in a particular virtual host. By default the SSL/TLS Protocol Engine is
1899 disabled for proxy both for the main server and all configured virtual hosts.</p>
1901 <p>Note that the SSLProxyEngine directive should not, in
1902 general, be included in a virtual host that will be acting as a
1903 forward proxy (using <Proxy> or <ProxyRequest> directives.
1904 SSLProxyEngine is not required to enable a forward proxy server to
1905 proxy SSL/TLS requests.</p>
1907 <example><title>Example</title>
1908 <highlight language="config">
1909 <VirtualHost _default_:443>
1912 </VirtualHost>
1916 </directivesynopsis>
1919 <name>SSLProxyProtocol</name>
1920 <description>Configure usable SSL protocol flavors for proxy usage</description>
1921 <syntax>SSLProxyProtocol [+|-]<em>protocol</em> ...</syntax>
1922 <default>SSLProxyProtocol all</default>
1923 <contextlist><context>server config</context>
1924 <context>virtual host</context></contextlist>
1925 <override>Options</override>
1928 <!-- XXX Why does this have an override and not .htaccess context? -->
1930 This directive can be used to control the SSL protocol flavors mod_ssl should
1931 use when establishing its server environment for proxy . It will only connect
1932 to servers using one of the provided protocols.</p>
1933 <p>Please refer to <directive module="mod_ssl">SSLProtocol</directive>
1934 for additional information.
1937 </directivesynopsis>
1940 <name>SSLProxyCipherSuite</name>
1941 <description>Cipher Suite available for negotiation in SSL
1942 proxy handshake</description>
1943 <syntax>SSLProxyCipherSuite <em>cipher-spec</em></syntax>
1944 <default>SSLProxyCipherSuite ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+EXP</default>
1945 <contextlist><context>server config</context>
1946 <context>virtual host</context>
1947 <context>directory</context>
1948 <context>.htaccess</context></contextlist>
1949 <override>AuthConfig</override>
1951 <p>Equivalent to <code>SSLCipherSuite</code>, but for the proxy connection.
1952 Please refer to <directive module="mod_ssl">SSLCipherSuite</directive>
1953 for additional information.</p>
1956 </directivesynopsis>
1958 <name>SSLProxyCACertificatePath</name>
1959 <description>Directory of PEM-encoded CA Certificates for
1960 Remote Server Auth</description>
1961 <syntax>SSLProxyCACertificatePath <em>directory-path</em></syntax>
1962 <contextlist><context>server config</context>
1963 <context>virtual host</context></contextlist>
1967 This directive sets the directory where you keep the Certificates of
1968 Certification Authorities (CAs) whose remote servers you deal with. These are used to
1969 verify the remote server certificate on Remote Server Authentication.</p>
1971 The files in this directory have to be PEM-encoded and are accessed through
1972 hash filenames. So usually you can't just place the Certificate files
1973 there: you also have to create symbolic links named
1974 <em>hash-value</em><code>.N</code>. And you should always make sure this directory
1975 contains the appropriate symbolic links.</p>
1976 <example><title>Example</title>
1977 <highlight language="config">
1978 SSLProxyCACertificatePath /usr/local/apache2/conf/ssl.crt/
1982 </directivesynopsis>
1985 <name>SSLProxyCACertificateFile</name>
1986 <description>File of concatenated PEM-encoded CA Certificates
1987 for Remote Server Auth</description>
1988 <syntax>SSLProxyCACertificateFile <em>file-path</em></syntax>
1989 <contextlist><context>server config</context>
1990 <context>virtual host</context></contextlist>
1994 This directive sets the <em>all-in-one</em> file where you can assemble the
1995 Certificates of Certification Authorities (CA) whose <em>remote servers</em> you deal
1996 with. These are used for Remote Server Authentication. Such a file is simply the
1997 concatenation of the various PEM-encoded Certificate files, in order of
1998 preference. This can be used alternatively and/or additionally to
1999 <directive module="mod_ssl">SSLProxyCACertificatePath</directive>.</p>
2000 <example><title>Example</title>
2001 <highlight language="config">
2002 SSLProxyCACertificateFile /usr/local/apache2/conf/ssl.crt/ca-bundle-remote-server.crt
2006 </directivesynopsis>
2009 <name>SSLProxyCARevocationPath</name>
2010 <description>Directory of PEM-encoded CA CRLs for
2011 Remote Server Auth</description>
2012 <syntax>SSLProxyCARevocationPath <em>directory-path</em></syntax>
2013 <contextlist><context>server config</context>
2014 <context>virtual host</context></contextlist>
2018 This directive sets the directory where you keep the Certificate Revocation
2019 Lists (CRL) of Certification Authorities (CAs) whose remote servers you deal with.
2020 These are used to revoke the remote server certificate on Remote Server Authentication.</p>
2022 The files in this directory have to be PEM-encoded and are accessed through
2023 hash filenames. So usually you have not only to place the CRL files there.
2024 Additionally you have to create symbolic links named
2025 <em>hash-value</em><code>.rN</code>. And you should always make sure this directory
2026 contains the appropriate symbolic links.</p>
2027 <example><title>Example</title>
2028 <highlight language="config">
2029 SSLProxyCARevocationPath /usr/local/apache2/conf/ssl.crl/
2033 </directivesynopsis>
2036 <name>SSLProxyCARevocationFile</name>
2037 <description>File of concatenated PEM-encoded CA CRLs for
2038 Remote Server Auth</description>
2039 <syntax>SSLProxyCARevocationFile <em>file-path</em></syntax>
2040 <contextlist><context>server config</context>
2041 <context>virtual host</context></contextlist>
2045 This directive sets the <em>all-in-one</em> file where you can
2046 assemble the Certificate Revocation Lists (CRL) of Certification
2047 Authorities (CA) whose <em>remote servers</em> you deal with. These are used
2048 for Remote Server Authentication. Such a file is simply the concatenation of
2049 the various PEM-encoded CRL files, in order of preference. This can be
2050 used alternatively and/or additionally to <directive
2051 module="mod_ssl">SSLProxyCARevocationPath</directive>.</p>
2052 <example><title>Example</title>
2053 <highlight language="config">
2054 SSLProxyCARevocationFile /usr/local/apache2/conf/ssl.crl/ca-bundle-remote-server.crl
2058 </directivesynopsis>
2061 <name>SSLProxyCARevocationCheck</name>
2062 <description>Enable CRL-based revocation checking for Remote Server Auth</description>
2063 <syntax>SSLProxyCARevocationCheck chain|leaf|none</syntax>
2064 <default>SSLProxyCARevocationCheck none</default>
2065 <contextlist><context>server config</context>
2066 <context>virtual host</context></contextlist>
2070 Enables certificate revocation list (CRL) checking for the
2071 <em>remote servers</em> you deal with. At least one of
2072 <directive module="mod_ssl">SSLProxyCARevocationFile</directive>
2073 or <directive module="mod_ssl">SSLProxyCARevocationPath</directive> must be
2074 configured. When set to <code>chain</code> (recommended setting),
2075 CRL checks are applied to all certificates in the chain, while setting it to
2076 <code>leaf</code> limits the checks to the end-entity cert.
2079 <title>When set to <code>chain</code> or <code>leaf</code>,
2080 CRLs <em>must</em> be available for successful validation</title>
2082 Prior to version 2.3.15, CRL checking in mod_ssl also succeeded when
2083 no CRL(s) were found in any of the locations configured with
2084 <directive module="mod_ssl">SSLProxyCARevocationFile</directive>
2085 or <directive module="mod_ssl">SSLProxyCARevocationPath</directive>.
2086 With the introduction of this directive, the behavior has been changed:
2087 when checking is enabled, CRLs <em>must</em> be present for the validation
2088 to succeed - otherwise it will fail with an
2089 <code>"unable to get certificate CRL"</code> error.
2092 <example><title>Example</title>
2093 <highlight language="config">
2094 SSLProxyCARevocationCheck chain
2098 </directivesynopsis>
2101 <name>SSLUserName</name>
2102 <description>Variable name to determine user name</description>
2103 <syntax>SSLUserName <em>varname</em></syntax>
2104 <contextlist><context>server config</context>
2105 <context>directory</context>
2106 <context>.htaccess</context></contextlist>
2107 <override>AuthConfig</override>
2111 This directive sets the "user" field in the Apache request object.
2112 This is used by lower modules to identify the user with a character
2113 string. In particular, this may cause the environment variable
2114 <code>REMOTE_USER</code> to be set. The <em>varname</em> can be
2115 any of the <a href="#envvars">SSL environment variables</a>.</p>
2117 <p>When the <code>FakeBasicAuth</code> option is enabled, this directive
2118 instead controls the value of the username embedded within the basic
2119 authentication header (see <a href="#ssloptions">SSLOptions</a>).</p>
2121 <example><title>Example</title>
2122 <highlight language="config">
2123 SSLUserName SSL_CLIENT_S_DN_CN
2127 </directivesynopsis>
2130 <name>SSLHonorCipherOrder</name>
2131 <description>Option to prefer the server's cipher preference order</description>
2132 <syntax>SSLHonorCipherOrder on|off</syntax>
2133 <default>SSLHonorCipherOrder off</default>
2134 <contextlist><context>server config</context>
2135 <context>virtual host</context></contextlist>
2138 <p>When choosing a cipher during an SSLv3 or TLSv1 handshake, normally
2139 the client's preference is used. If this directive is enabled, the
2140 server's preference will be used instead.</p>
2141 <example><title>Example</title>
2142 <highlight language="config">
2143 SSLHonorCipherOrder on
2147 </directivesynopsis>
2150 <name>SSLCryptoDevice</name>
2151 <description>Enable use of a cryptographic hardware accelerator</description>
2152 <syntax>SSLCryptoDevice <em>engine</em></syntax>
2153 <default>SSLCryptoDevice builtin</default>
2154 <contextlist><context>server config</context></contextlist>
2158 This directive enables use of a cryptographic hardware accelerator
2159 board to offload some of the SSL processing overhead. This directive
2160 can only be used if the SSL toolkit is built with "engine" support;
2161 OpenSSL 0.9.7 and later releases have "engine" support by default, the
2162 separate "-engine" releases of OpenSSL 0.9.6 must be used.</p>
2164 <p>To discover which engine names are supported, run the command
2165 "<code>openssl engine</code>".</p>
2167 <example><title>Example</title>
2168 <highlight language="config">
2169 # For a Broadcom accelerator:
2170 SSLCryptoDevice ubsec
2174 </directivesynopsis>
2177 <name>SSLOCSPEnable</name>
2178 <description>Enable OCSP validation of the client certificate chain</description>
2179 <syntax>SSLOCSPEnable on|off</syntax>
2180 <default>SSLOCSPEnable off</default>
2181 <contextlist><context>server config</context>
2182 <context>virtual host</context></contextlist>
2185 <p>This option enables OCSP validation of the client certificate
2186 chain. If this option is enabled, certificates in the client's
2187 certificate chain will be validated against an OCSP responder after
2188 normal verification (including CRL checks) have taken place.</p>
2190 <p>The OCSP responder used is either extracted from the certificate
2191 itself, or derived by configuration; see the
2192 <directive module="mod_ssl">SSLOCSPDefaultResponder</directive> and
2193 <directive module="mod_ssl">SSLOCSPOverrideResponder</directive>
2196 <example><title>Example</title>
2197 <highlight language="config">
2200 SSLOCSPDefaultResponder http://responder.example.com:8888/responder
2201 SSLOCSPOverrideResponder on
2205 </directivesynopsis>
2208 <name>SSLOCSPDefaultResponder</name>
2209 <description>Set the default responder URI for OCSP validation</description>
2210 <syntax>SSLOCSDefaultResponder <em>uri</em></syntax>
2211 <contextlist><context>server config</context>
2212 <context>virtual host</context></contextlist>
2215 <p>This option sets the default OCSP responder to use. If <directive
2216 module="mod_ssl">SSLOCSPOverrideResponder</directive> is not enabled,
2217 the URI given will be used only if no responder URI is specified in
2218 the certificate being verified.</p>
2220 </directivesynopsis>
2223 <name>SSLOCSPOverrideResponder</name>
2224 <description>Force use of the default responder URI for OCSP validation</description>
2225 <syntax>SSLOCSPOverrideResponder on|off</syntax>
2226 <default>SSLOCSPOverrideResponder off</default>
2227 <contextlist><context>server config</context>
2228 <context>virtual host</context></contextlist>
2231 <p>This option forces the configured default OCSP responder to be used
2232 during OCSP certificate validation, regardless of whether the
2233 certificate being validated references an OCSP responder.</p>
2235 </directivesynopsis>
2238 <name>SSLOCSPResponseTimeSkew</name>
2239 <description>Maximum allowable time skew for OCSP response validation</description>
2240 <syntax>SSLOCSPResponseTimeSkew <em>seconds</em></syntax>
2241 <default>SSLOCSPResponseTimeSkew 300</default>
2242 <contextlist><context>server config</context>
2243 <context>virtual host</context></contextlist>
2246 <p>This option sets the maximum allowable time skew for OCSP responses
2247 (when checking their <code>thisUpdate</code> and <code>nextUpdate</code> fields).</p>
2249 </directivesynopsis>
2252 <name>SSLOCSPResponseMaxAge</name>
2253 <description>Maximum allowable age for OCSP responses</description>
2254 <syntax>SSLOCSPResponseMaxAge <em>seconds</em></syntax>
2255 <default>SSLOCSPResponseMaxAge -1</default>
2256 <contextlist><context>server config</context>
2257 <context>virtual host</context></contextlist>
2260 <p>This option sets the maximum allowable age ("freshness") for OCSP responses.
2261 The default value (<code>-1</code>) does not enforce a maximum age,
2262 which means that OCSP responses are considered valid as long as their
2263 <code>nextUpdate</code> field is in the future.</p>
2265 </directivesynopsis>
2268 <name>SSLOCSPResponderTimeout</name>
2269 <description>Timeout for OCSP queries</description>
2270 <syntax>SSLOCSPResponderTimeout <em>seconds</em></syntax>
2271 <default>SSLOCSPResponderTimeout 10</default>
2272 <contextlist><context>server config</context>
2273 <context>virtual host</context></contextlist>
2276 <p>This option sets the timeout for queries to OCSP responders, when
2277 <directive module="mod_ssl">SSLOCSPEnable</directive> is turned on.</p>
2279 </directivesynopsis>
2282 <name>SSLOCSPUseRequestNonce</name>
2283 <description>Use a nonce within OCSP queries</description>
2284 <syntax>SSLOCSPUseRequestNonce on|off</syntax>
2285 <default>SSLOCSPUseRequestNonce on</default>
2286 <contextlist><context>server config</context>
2287 <context>virtual host</context></contextlist>
2288 <compatibility>Available in httpd 2.5-dev and later</compatibility>
2291 <p>This option determines whether queries to OCSP responders should contain
2292 a nonce or not. By default, a query nonce is always used and checked against
2293 the response's one. When the responder does not use nonces (eg. Microsoft OCSP
2294 Responder), this option ought to be turned <code>off</code>.</p>
2296 </directivesynopsis>
2299 <name>SSLInsecureRenegotiation</name>
2300 <description>Option to enable support for insecure renegotiation</description>
2301 <syntax>SSLInsecureRenegotiation on|off</syntax>
2302 <default>SSLInsecureRenegotiation off</default>
2303 <contextlist><context>server config</context>
2304 <context>virtual host</context></contextlist>
2305 <compatibility>Available if using OpenSSL 0.9.8m or later</compatibility>
2308 <p>As originally specified, all versions of the SSL and TLS protocols
2309 (up to and including TLS/1.2) were vulnerable to a Man-in-the-Middle
2311 (<a href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2009-3555">CVE-2009-3555</a>)
2312 during a renegotiation. This vulnerability allowed an attacker to
2313 "prefix" a chosen plaintext to the HTTP request as seen by the web
2314 server. A protocol extension was developed which fixed this
2315 vulnerability if supported by both client and server.</p>
2317 <p>If <module>mod_ssl</module> is linked against OpenSSL version 0.9.8m
2318 or later, by default renegotiation is only supported with
2319 clients supporting the new protocol extension. If this directive is
2320 enabled, renegotiation will be allowed with old (unpatched) clients,
2321 albeit insecurely.</p>
2323 <note type="warning"><title>Security warning</title>
2324 <p>If this directive is enabled, SSL connections will be vulnerable to
2325 the Man-in-the-Middle prefix attack as described
2326 in <a href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2009-3555">CVE-2009-3555</a>.</p>
2329 <example><title>Example</title>
2330 <highlight language="config">
2331 SSLInsecureRenegotiation on
2335 <p>The <code>SSL_SECURE_RENEG</code> environment variable can be used
2336 from an SSI or CGI script to determine whether secure renegotiation is
2337 supported for a given SSL connection.</p>
2340 </directivesynopsis>
2343 <name>SSLUseStapling</name>
2344 <description>Enable stapling of OCSP responses in the TLS handshake</description>
2345 <syntax>SSLUseStapling on|off</syntax>
2346 <default>SSLUseStapling off</default>
2347 <contextlist><context>server config</context>
2348 <context>virtual host</context></contextlist>
2349 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2352 <p>This option enables OCSP stapling, as defined by the "Certificate
2353 Status Request" TLS extension specified in RFC 6066. If enabled (and
2354 requested by the client), mod_ssl will include an OCSP response
2355 for its own certificate in the TLS handshake. Configuring an
2356 <directive module="mod_ssl">SSLStaplingCache</directive> is a
2357 prerequisite for enabling OCSP stapling.</p>
2359 <p>OCSP stapling relieves the client of querying the OCSP responder
2360 on its own, but it should be noted that with the RFC 6066 specification,
2361 the server's <code>CertificateStatus</code> reply may only include an
2362 OCSP response for a single cert. For server certificates with intermediate
2363 CA certificates in their chain (the typical case nowadays),
2364 stapling in its current implementation therefore only partially achieves the
2365 stated goal of "saving roundtrips and resources" - see also
2366 <a href="http://www.ietf.org/rfc/rfc6961.txt">RFC 6961</a>
2367 (TLS Multiple Certificate Status Extension).
2370 </directivesynopsis>
2373 <name>SSLStaplingCache</name>
2374 <description>Configures the OCSP stapling cache</description>
2375 <syntax>SSLStaplingCache <em>type</em></syntax>
2376 <contextlist><context>server config</context></contextlist>
2377 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2380 <p>Configures the cache used to store OCSP responses which get included
2381 in the TLS handshake if <directive module="mod_ssl">SSLUseStapling</directive>
2382 is enabled. Configuration of a cache is mandatory for OCSP stapling.
2383 With the exception of <code>none</code> and <code>nonenotnull</code>,
2384 the same storage types are supported as with
2385 <directive module="mod_ssl">SSLSessionCache</directive>.</p>
2387 </directivesynopsis>
2390 <name>SSLStaplingResponseTimeSkew</name>
2391 <description>Maximum allowable time skew for OCSP stapling response validation</description>
2392 <syntax>SSLStaplingResponseTimeSkew <em>seconds</em></syntax>
2393 <default>SSLStaplingResponseTimeSkew 300</default>
2394 <contextlist><context>server config</context>
2395 <context>virtual host</context></contextlist>
2396 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2399 <p>This option sets the maximum allowable time skew when mod_ssl checks the
2400 <code>thisUpdate</code> and <code>nextUpdate</code> fields of OCSP responses
2401 which get included in the TLS handshake (OCSP stapling). Only applicable
2402 if <directive module="mod_ssl">SSLUseStapling</directive> is turned on.</p>
2404 </directivesynopsis>
2407 <name>SSLStaplingResponderTimeout</name>
2408 <description>Timeout for OCSP stapling queries</description>
2409 <syntax>SSLStaplingResponderTimeout <em>seconds</em></syntax>
2410 <default>SSLStaplingResponderTimeout 10</default>
2411 <contextlist><context>server config</context>
2412 <context>virtual host</context></contextlist>
2413 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2416 <p>This option sets the timeout for queries to OCSP responders when
2417 <directive module="mod_ssl">SSLUseStapling</directive> is enabled
2418 and mod_ssl is querying a responder for OCSP stapling purposes.</p>
2420 </directivesynopsis>
2423 <name>SSLStaplingResponseMaxAge</name>
2424 <description>Maximum allowable age for OCSP stapling responses</description>
2425 <syntax>SSLStaplingResponseMaxAge <em>seconds</em></syntax>
2426 <default>SSLStaplingResponseMaxAge -1</default>
2427 <contextlist><context>server config</context>
2428 <context>virtual host</context></contextlist>
2429 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2432 <p>This option sets the maximum allowable age ("freshness") when
2433 considering OCSP responses for stapling purposes, i.e. when
2434 <directive module="mod_ssl">SSLUseStapling</directive> is turned on.
2435 The default value (<code>-1</code>) does not enforce a maximum age,
2436 which means that OCSP responses are considered valid as long as their
2437 <code>nextUpdate</code> field is in the future.</p>
2439 </directivesynopsis>
2442 <name>SSLStaplingStandardCacheTimeout</name>
2443 <description>Number of seconds before expiring responses in the OCSP stapling cache</description>
2444 <syntax>SSLStaplingStandardCacheTimeout <em>seconds</em></syntax>
2445 <default>SSLStaplingStandardCacheTimeout 3600</default>
2446 <contextlist><context>server config</context>
2447 <context>virtual host</context></contextlist>
2448 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2451 <p>Sets the timeout in seconds before responses in the OCSP stapling cache
2452 (configured through <directive module="mod_ssl">SSLStaplingCache</directive>)
2453 will expire. This directive applies to <em>valid</em> responses, while
2454 <directive module="mod_ssl">SSLStaplingErrorCacheTimeout</directive> is
2455 used for controlling the timeout for invalid/unavailable responses.
2458 </directivesynopsis>
2461 <name>SSLStaplingReturnResponderErrors</name>
2462 <description>Pass stapling related OCSP errors on to client</description>
2463 <syntax>SSLStaplingReturnResponderErrors on|off</syntax>
2464 <default>SSLStaplingReturnResponderErrors on</default>
2465 <contextlist><context>server config</context>
2466 <context>virtual host</context></contextlist>
2467 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2470 <p>When enabled, mod_ssl will pass responses from unsuccessful
2471 stapling related OCSP queries (such as status errors, expired responses etc.)
2472 on to the client. If set to <code>off</code>, no stapled responses
2473 for failed queries will be included in the TLS handshake.</p>
2475 </directivesynopsis>
2478 <name>SSLStaplingFakeTryLater</name>
2479 <description>Synthesize "tryLater" responses for failed OCSP stapling queries</description>
2480 <syntax>SSLStaplingFakeTryLater on|off</syntax>
2481 <default>SSLStaplingFakeTryLater on</default>
2482 <contextlist><context>server config</context>
2483 <context>virtual host</context></contextlist>
2484 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2487 <p>When enabled and a query to an OCSP responder for stapling
2488 purposes fails, mod_ssl will synthesize a "tryLater" response for the
2489 client. Only effective if <directive
2490 module="mod_ssl">SSLStaplingReturnResponderErrors</directive>
2491 is also enabled.</p>
2493 </directivesynopsis>
2496 <name>SSLStaplingErrorCacheTimeout</name>
2497 <description>Number of seconds before expiring invalid responses in the OCSP stapling cache</description>
2498 <syntax>SSLStaplingErrorCacheTimeout <em>seconds</em></syntax>
2499 <default>SSLStaplingErrorCacheTimeout 600</default>
2500 <contextlist><context>server config</context>
2501 <context>virtual host</context></contextlist>
2502 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2505 <p>Sets the timeout in seconds before <em>invalid</em> responses
2506 in the OCSP stapling cache (configured through <directive
2507 module="mod_ssl">SSLStaplingCache</directive>) will expire.
2508 To set the cache timeout for valid responses, see
2509 <directive module="mod_ssl">SSLStaplingStandardCacheTimeout</directive>.</p>
2511 </directivesynopsis>
2514 <name>SSLStaplingForceURL</name>
2515 <description>Override the OCSP responder URI specified in the certificate's AIA extension</description>
2516 <syntax>SSLStaplingForceURL <em>uri</em></syntax>
2517 <contextlist><context>server config</context>
2518 <context>virtual host</context></contextlist>
2519 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2522 <p>This directive overrides the URI of an OCSP responder as obtained from
2523 the authorityInfoAccess (AIA) extension of the certificate.
2524 Of potential use when going through a proxy for retrieving OCSP queries.</p>
2526 </directivesynopsis>
2529 <name>SSLSessionTicketKeyFile</name>
2530 <description>Persistent encryption/decryption key for TLS session tickets</description>
2531 <syntax>SSLSessionTicketKeyFile <em>file-path</em></syntax>
2532 <contextlist><context>server config</context>
2533 <context>virtual host</context></contextlist>
2534 <compatibility>Available in httpd 2.4.0 and later, if using OpenSSL 0.9.8h or later</compatibility>
2537 <p>Optionally configures a secret key for encrypting and decrypting
2538 TLS session tickets, as defined in
2539 <a href="http://www.ietf.org/rfc/rfc5077.txt">RFC 5077</a>.
2540 Primarily suitable for clustered environments where TLS sessions information
2541 should be shared between multiple nodes. For single-instance httpd setups,
2542 it is recommended to <em>not</em> configure a ticket key file, but to
2543 rely on (random) keys generated by mod_ssl at startup, instead.</p>
2544 <p>The ticket key file must contain 48 bytes of random data,
2545 preferrably created from a high-entropy source. On a Unix-based system,
2546 a ticket key file can be created as follows:</p>
2549 dd if=/dev/random of=/path/to/file.tkey bs=1 count=48
2552 <p>Ticket keys should be rotated (replaced) on a frequent basis,
2553 as this is the only way to invalidate an existing session ticket -
2554 OpenSSL currently doesn't allow to specify a limit for ticket lifetimes.</p>
2556 <note type="warning">
2557 <p>The ticket key file contains sensitive keying material and should
2558 be protected with file permissions similar to those used for
2559 <directive module="mod_ssl">SSLCertificateKeyFile</directive>.</p>
2562 </directivesynopsis>
2565 <name>SSLCompression</name>
2566 <description>Enable compression on the SSL level</description>
2567 <syntax>SSLCompression on|off</syntax>
2568 <default>SSLCompression off</default>
2569 <contextlist><context>server config</context>
2570 <context>virtual host</context></contextlist>
2571 <compatibility>Available in httpd 2.4.3 and later, if using OpenSSL 0.9.8 or later;
2572 virtual host scope available if using OpenSSL 1.0.0 or later.
2573 The default used to be <code>on</code> in version 2.4.3.</compatibility>
2576 <p>This directive allows to enable compression on the SSL level.</p>
2577 <note type="warning">
2578 <p>Enabling compression causes security issues in most setups (the so called
2582 </directivesynopsis>
2585 <name>SSLOpenSSLConfCmd</name>
2586 <description>Configure OpenSSL parameters through its <em>SSL_CONF</em> API</description>
2587 <syntax>SSLOpenSSLConfCmd <em>command-name</em> <em>command-value</em></syntax>
2588 <contextlist><context>server config</context>
2589 <context>virtual host</context></contextlist>
2590 <compatibility>Available in httpd 2.4.8 and later, if using OpenSSL 1.0.2 or later</compatibility>
2593 <p>This directive exposes OpenSSL's <em>SSL_CONF</em> API to mod_ssl,
2594 allowing a flexible configuration of OpenSSL parameters without the need
2595 of implementing additional <module>mod_ssl</module> directives when new
2596 features are added to OpenSSL.</p>
2598 <p>The set of available <directive>SSLOpenSSLConfCmd</directive> commands
2599 depends on the OpenSSL version being used for <module>mod_ssl</module>
2600 (at least version 1.0.2 is required). For a list of supported command
2601 names, see the section <em>Supported configuration file commands</em> in the
2602 <a href="http://www.openssl.org/docs/ssl/SSL_CONF_cmd.html#SUPPORTED_CONFIGURATION_FILE_COM">SSL_CONF_cmd(3)</a> manual page for OpenSSL.</p>
2604 <p>Some of the <directive>SSLOpenSSLConfCmd</directive> commands can be used
2605 as an alternative to existing directives (such as
2606 <directive module="mod_ssl">SSLCipherSuite</directive> or
2607 <directive module="mod_ssl">SSLProtocol</directive>),
2608 though it should be noted that the syntax / allowable values for the parameters
2609 may sometimes differ.</p>
2611 <example><title>Examples</title>
2612 <highlight language="config">
2613 SSLOpenSSLConfCmd Options -SessionTicket,ServerPreference
2614 SSLOpenSSLConfCmd ECDHParameters brainpoolP256r1
2615 SSLOpenSSLConfCmd ServerInfoFile /usr/local/apache2/conf/server-info.pem
2616 SSLOpenSSLConfCmd Protocol "-ALL, TLSv1.2"
2617 SSLOpenSSLConfCmd SignatureAlgorithms RSA+SHA384:ECDSA+SHA256
2621 </directivesynopsis>