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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_SAN_Email_</code><em>n</em></td> <td>string</td> <td>Client certificate's subjectAltName extension entries of type rfc822Name</td></tr>
79 <tr><td><code>SSL_CLIENT_SAN_DNS_</code><em>n</em></td> <td>string</td> <td>Client certificate's subjectAltName extension entries of type dNSName</td></tr>
80 <tr><td><code>SSL_CLIENT_I_DN</code></td> <td>string</td> <td>Issuer DN of client's certificate</td></tr>
81 <tr><td><code>SSL_CLIENT_I_DN_</code><em>x509</em></td> <td>string</td> <td>Component of client's Issuer DN</td></tr>
82 <tr><td><code>SSL_CLIENT_V_START</code></td> <td>string</td> <td>Validity of client's certificate (start time)</td></tr>
83 <tr><td><code>SSL_CLIENT_V_END</code></td> <td>string</td> <td>Validity of client's certificate (end time)</td></tr>
84 <tr><td><code>SSL_CLIENT_V_REMAIN</code></td> <td>string</td> <td>Number of days until client's certificate expires</td></tr>
85 <tr><td><code>SSL_CLIENT_A_SIG</code></td> <td>string</td> <td>Algorithm used for the signature of client's certificate</td></tr>
86 <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>
87 <tr><td><code>SSL_CLIENT_CERT</code></td> <td>string</td> <td>PEM-encoded client certificate</td></tr>
88 <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>
89 <tr><td><code>SSL_CLIENT_CERT_RFC4523_CEA</code></td> <td>string</td> <td>Serial number and issuer of the certificate. The format matches that of the CertificateExactAssertion in RFC4523</td></tr>
90 <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>
91 <tr><td><code>SSL_SERVER_M_VERSION</code></td> <td>string</td> <td>The version of the server certificate</td></tr>
92 <tr><td><code>SSL_SERVER_M_SERIAL</code></td> <td>string</td> <td>The serial of the server certificate</td></tr>
93 <tr><td><code>SSL_SERVER_S_DN</code></td> <td>string</td> <td>Subject DN in server's certificate</td></tr>
94 <tr><td><code>SSL_SERVER_SAN_Email_</code><em>n</em></td> <td>string</td> <td>Server certificate's subjectAltName extension entries of type rfc822Name</td></tr>
95 <tr><td><code>SSL_SERVER_SAN_DNS_</code><em>n</em></td> <td>string</td> <td>Server certificate's subjectAltName extension entries of type dNSName</td></tr>
96 <tr><td><code>SSL_SERVER_S_DN_</code><em>x509</em></td> <td>string</td> <td>Component of server's Subject DN</td></tr>
97 <tr><td><code>SSL_SERVER_I_DN</code></td> <td>string</td> <td>Issuer DN of server's certificate</td></tr>
98 <tr><td><code>SSL_SERVER_I_DN_</code><em>x509</em></td> <td>string</td> <td>Component of server's Issuer DN</td></tr>
99 <tr><td><code>SSL_SERVER_V_START</code></td> <td>string</td> <td>Validity of server's certificate (start time)</td></tr>
100 <tr><td><code>SSL_SERVER_V_END</code></td> <td>string</td> <td>Validity of server's certificate (end time)</td></tr>
101 <tr><td><code>SSL_SERVER_A_SIG</code></td> <td>string</td> <td>Algorithm used for the signature of server's certificate</td></tr>
102 <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>
103 <tr><td><code>SSL_SERVER_CERT</code></td> <td>string</td> <td>PEM-encoded server certificate</td></tr>
104 <tr><td><code>SSL_SRP_USER</code></td> <td>string</td> <td>SRP username</td></tr>
105 <tr><td><code>SSL_SRP_USERINFO</code></td> <td>string</td> <td>SRP user info</td></tr>
106 <tr><td><code>SSL_TLS_SNI</code></td> <td>string</td> <td>Contents of the SNI TLS extension (if supplied with ClientHello)</td></tr>
109 <p><em>x509</em> specifies a component of an X.509 DN; one of
110 <code>C,ST,L,O,OU,CN,T,I,G,S,D,UID,Email</code>. In Apache 2.1 and
111 later, <em>x509</em> may also include a numeric <code>_n</code>
112 suffix. If the DN in question contains multiple attributes of the
113 same name, this suffix is used as a zero-based index to select a
114 particular attribute. For example, where the server certificate
115 subject DN included two OU attributes, <code>SSL_SERVER_S_DN_OU_0</code>
117 <code>SSL_SERVER_S_DN_OU_1</code> could be used to reference each. A
118 variable name without a <code>_n</code> suffix is equivalent to that
119 name with a <code>_0</code> suffix; the first (or only) attribute.
120 When the environment table is populated using
121 the <code>StdEnvVars</code> option of
122 the <directive module="mod_ssl">SSLOptions</directive> directive, the
123 first (or only) attribute of any DN is added only under a non-suffixed
124 name; i.e. no <code>_0</code> suffixed entries are added.</p>
126 <p>The format of the <em>*_DN</em> variables has changed in Apache HTTPD
127 2.3.11. See the <code>LegacyDNStringFormat</code> option for
128 <directive module="mod_ssl">SSLOptions</directive> for details.</p>
130 <p><code>SSL_CLIENT_V_REMAIN</code> is only available in version 2.1
133 <p>A number of additional environment variables can also be used
134 in <directive>SSLRequire</directive> expressions, or in custom log
137 <note><pre>HTTP_USER_AGENT PATH_INFO AUTH_TYPE
138 HTTP_REFERER QUERY_STRING SERVER_SOFTWARE
139 HTTP_COOKIE REMOTE_HOST API_VERSION
140 HTTP_FORWARDED REMOTE_IDENT TIME_YEAR
141 HTTP_HOST IS_SUBREQ TIME_MON
142 HTTP_PROXY_CONNECTION DOCUMENT_ROOT TIME_DAY
143 HTTP_ACCEPT SERVER_ADMIN TIME_HOUR
144 THE_REQUEST SERVER_NAME TIME_MIN
145 REQUEST_FILENAME SERVER_PORT TIME_SEC
146 REQUEST_METHOD SERVER_PROTOCOL TIME_WDAY
147 REQUEST_SCHEME REMOTE_ADDR TIME
148 REQUEST_URI REMOTE_USER</pre></note>
150 <p>In these contexts, two special formats can also be used:</p>
153 <dt><code>ENV:<em>variablename</em></code></dt>
154 <dd>This will expand to the standard environment
155 variable <em>variablename</em>.</dd>
157 <dt><code>HTTP:<em>headername</em></code></dt>
158 <dd>This will expand to the value of the request header with name
159 <em>headername</em>.</dd>
164 <section id="logformats"><title>Custom Log Formats</title>
166 <p>When <module>mod_ssl</module> is built into Apache or at least
167 loaded (under DSO situation) additional functions exist for the <a
168 href="mod_log_config.html#formats">Custom Log Format</a> of
169 <module>mod_log_config</module>. First there is an
170 additional ``<code>%{</code><em>varname</em><code>}x</code>''
171 eXtension format function which can be used to expand any variables
172 provided by any module, especially those provided by mod_ssl which can
173 you find in the above table.</p>
175 For backward compatibility there is additionally a special
176 ``<code>%{</code><em>name</em><code>}c</code>'' cryptography format function
177 provided. Information about this function is provided in the <a
178 href="../ssl/ssl_compat.html">Compatibility</a> chapter.</p>
179 <example><title>Example</title>
180 <highlight language="config">
181 CustomLog logs/ssl_request_log "%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"
186 <section id="notes"><title>Request Notes</title>
188 <p><module>mod_ssl</module> sets "notes" for the request which can be
189 used in logging with the <code>%{<em>name</em>}n</code> format
190 string in <module>mod_log_config</module>.</p>
192 <p>The notes supported are as follows:</p>
195 <dt><code>ssl-access-forbidden</code></dt>
196 <dd>This note is set to the value <code>1</code> if access was
197 denied due to an <directive>SSLRequire</directive>
198 or <directive>SSLRequireSSL</directive> directive.</dd>
200 <dt><code>ssl-secure-reneg</code></dt>
201 <dd>If <module>mod_ssl</module> is built against a version of
202 OpenSSL which supports the secure renegotiation extension, this note
203 is set to the value <code>1</code> if SSL is in used for the current
204 connection, and the client also supports the secure renegotiation
205 extension. If the client does not support the secure renegotiation
206 extension, the note is set to the value <code>0</code>.
207 If <module>mod_ssl</module> is not built against a version of
208 OpenSSL which supports secure renegotiation, or if SSL is not in use
209 for the current connection, the note is not set.</dd>
214 <section id="authzproviders"><title>Authorization providers for use with Require</title>
216 <p><module>mod_ssl</module> provides a few authentication providers for use
217 with <module>mod_authz_core</module>'s
218 <directive module="mod_authz_core">Require</directive> directive.</p>
220 <section id="reqssl"><title>Require ssl</title>
222 <p>The <code>ssl</code> provider denies access if a connection is not
223 encrypted with SSL. This is similar to the
224 <directive>SSLRequireSSL</directive> directive.</p>
226 <highlight language="config">
232 <section id="reqverifyclient"><title>Require ssl-verify-client</title>
234 <p>The <code>ssl</code> provider allows access if the user is
235 authenticated with a valid client certificate. This is only
236 useful if <code>SSLVerifyClient optional</code> is in effect.</p>
238 <p>The following example grants access if the user is authenticated
239 either with a client certificate or by username and password.</p>
241 <highlight language="config">
242 Require ssl-verify-client<br/>
251 <name>SSLPassPhraseDialog</name>
252 <description>Type of pass phrase dialog for encrypted private
254 <syntax>SSLPassPhraseDialog <em>type</em></syntax>
255 <default>SSLPassPhraseDialog builtin</default>
256 <contextlist><context>server config</context></contextlist>
260 When Apache starts up it has to read the various Certificate (see
261 <directive module="mod_ssl">SSLCertificateFile</directive>) and
262 Private Key (see <directive
263 module="mod_ssl">SSLCertificateKeyFile</directive>) files of the
264 SSL-enabled virtual servers. Because for security reasons the Private
265 Key files are usually encrypted, mod_ssl needs to query the
266 administrator for a Pass Phrase in order to decrypt those files. This
267 query can be done in two ways which can be configured by
270 <li><code>builtin</code>
272 This is the default where an interactive terminal dialog occurs at startup
273 time just before Apache detaches from the terminal. Here the administrator
274 has to manually enter the Pass Phrase for each encrypted Private Key file.
275 Because a lot of SSL-enabled virtual hosts can be configured, the
276 following reuse-scheme is used to minimize the dialog: When a Private Key
277 file is encrypted, all known Pass Phrases (at the beginning there are
278 none, of course) are tried. If one of those known Pass Phrases succeeds no
279 dialog pops up for this particular Private Key file. If none succeeded,
280 another Pass Phrase is queried on the terminal and remembered for the next
281 round (where it perhaps can be reused).</p>
283 This scheme allows mod_ssl to be maximally flexible (because for N encrypted
284 Private Key files you <em>can</em> use N different Pass Phrases - but then
285 you have to enter all of them, of course) while minimizing the terminal
286 dialog (i.e. when you use a single Pass Phrase for all N Private Key files
287 this Pass Phrase is queried only once).</p></li>
289 <li><code>|/path/to/program [args...]</code>
291 <p>This mode allows an external program to be used which acts as a
292 pipe to a particular input device; the program is sent the standard
293 prompt text used for the <code>builtin</code> mode on
294 <code>stdin</code>, and is expected to write password strings on
295 <code>stdout</code>. If several passwords are needed (or an
296 incorrect password is entered), additional prompt text will be
297 written subsequent to the first password being returned, and more
298 passwords must then be written back.</p></li>
300 <li><code>exec:/path/to/program</code>
302 Here an external program is configured which is called at startup for each
303 encrypted Private Key file. It is called with one argument, a string of the
304 form ``<code>servername:portnumber:index</code>'' (with <code>index</code>
305 being a zero-based sequence number), which indicates for which server,
306 TCP port and certificate number it has to print the corresponding
307 Pass Phrase to <code>stdout</code>. The intent is that this external
308 program first runs security checks to make sure that the system is not
309 compromised by an attacker, and only when these checks were passed
310 successfully it provides the Pass Phrase.</p>
312 Both these security checks, and the way the Pass Phrase is determined, can
313 be as complex as you like. Mod_ssl just defines the interface: an
314 executable program which provides the Pass Phrase on <code>stdout</code>.
315 Nothing more or less! So, if you're really paranoid about security, here
316 is your interface. Anything else has to be left as an exercise to the
317 administrator, because local security requirements are so different.</p>
319 The reuse-algorithm above is used here, too. In other words: The external
320 program is called only once per unique Pass Phrase.</p></li>
322 <example><title>Example</title>
323 <highlight language="config">
324 SSLPassPhraseDialog exec:/usr/local/apache/sbin/pp-filter
331 <name>SSLRandomSeed</name>
332 <description>Pseudo Random Number Generator (PRNG) seeding
334 <syntax>SSLRandomSeed <em>context</em> <em>source</em>
335 [<em>bytes</em>]</syntax>
336 <contextlist><context>server config</context></contextlist>
340 This configures one or more sources for seeding the Pseudo Random Number
341 Generator (PRNG) in OpenSSL at startup time (<em>context</em> is
342 <code>startup</code>) and/or just before a new SSL connection is established
343 (<em>context</em> is <code>connect</code>). This directive can only be used
344 in the global server context because the PRNG is a global facility.</p>
346 The following <em>source</em> variants are available:</p>
348 <li><code>builtin</code>
349 <p> This is the always available builtin seeding source. Its usage
350 consumes minimum CPU cycles under runtime and hence can be always used
351 without drawbacks. The source used for seeding the PRNG contains of the
352 current time, the current process id and (when applicable) a randomly
353 chosen 1KB extract of the inter-process scoreboard structure of Apache.
354 The drawback is that this is not really a strong source and at startup
355 time (where the scoreboard is still not available) this source just
356 produces a few bytes of entropy. So you should always, at least for the
357 startup, use an additional seeding source.</p></li>
358 <li><code>file:/path/to/source</code>
360 This variant uses an external file <code>/path/to/source</code> as the
361 source for seeding the PRNG. When <em>bytes</em> is specified, only the
362 first <em>bytes</em> number of bytes of the file form the entropy (and
363 <em>bytes</em> is given to <code>/path/to/source</code> as the first
364 argument). When <em>bytes</em> is not specified the whole file forms the
365 entropy (and <code>0</code> is given to <code>/path/to/source</code> as
366 the first argument). Use this especially at startup time, for instance
367 with an available <code>/dev/random</code> and/or
368 <code>/dev/urandom</code> devices (which usually exist on modern Unix
369 derivatives like FreeBSD and Linux).</p>
371 <em>But be careful</em>: Usually <code>/dev/random</code> provides only as
372 much entropy data as it actually has, i.e. when you request 512 bytes of
373 entropy, but the device currently has only 100 bytes available two things
374 can happen: On some platforms you receive only the 100 bytes while on
375 other platforms the read blocks until enough bytes are available (which
376 can take a long time). Here using an existing <code>/dev/urandom</code> is
377 better, because it never blocks and actually gives the amount of requested
378 data. The drawback is just that the quality of the received data may not
379 be the best.</p></li>
381 <li><code>exec:/path/to/program</code>
383 This variant uses an external executable
384 <code>/path/to/program</code> as the source for seeding the
385 PRNG. When <em>bytes</em> is specified, only the first
386 <em>bytes</em> number of bytes of its <code>stdout</code> contents
387 form the entropy. When <em>bytes</em> is not specified, the
388 entirety of the data produced on <code>stdout</code> form the
389 entropy. Use this only at startup time when you need a very strong
390 seeding with the help of an external program (for instance as in
391 the example above with the <code>truerand</code> utility you can
392 find in the mod_ssl distribution which is based on the AT&T
393 <em>truerand</em> library). Using this in the connection context
394 slows down the server too dramatically, of course. So usually you
395 should avoid using external programs in that context.</p></li>
396 <li><code>egd:/path/to/egd-socket</code> (Unix only)
398 This variant uses the Unix domain socket of the
399 external Entropy Gathering Daemon (EGD) (see <a
400 href="http://www.lothar.com/tech/crypto/">http://www.lothar.com/tech
401 /crypto/</a>) to seed the PRNG. Use this if no random device exists
402 on your platform.</p></li>
404 <example><title>Example</title>
405 <highlight language="config">
406 SSLRandomSeed startup builtin
407 SSLRandomSeed startup file:/dev/random
408 SSLRandomSeed startup file:/dev/urandom 1024
409 SSLRandomSeed startup exec:/usr/local/bin/truerand 16
410 SSLRandomSeed connect builtin
411 SSLRandomSeed connect file:/dev/random
412 SSLRandomSeed connect file:/dev/urandom 1024
419 <name>SSLSessionCache</name>
420 <description>Type of the global/inter-process SSL Session
422 <syntax>SSLSessionCache <em>type</em></syntax>
423 <default>SSLSessionCache none</default>
424 <contextlist><context>server config</context></contextlist>
428 This configures the storage type of the global/inter-process SSL Session
429 Cache. This cache is an optional facility which speeds up parallel request
430 processing. For requests to the same server process (via HTTP keep-alive),
431 OpenSSL already caches the SSL session information locally. But because modern
432 clients request inlined images and other data via parallel requests (usually
433 up to four parallel requests are common) those requests are served by
434 <em>different</em> pre-forked server processes. Here an inter-process cache
435 helps to avoid unnecessary session handshakes.</p>
437 The following five storage <em>type</em>s are currently supported:</p>
439 <li><code>none</code>
441 <p>This disables the global/inter-process Session Cache. This
442 will incur a noticeable speed penalty and may cause problems if
443 using certain browsers, particularly if client certificates are
444 enabled. This setting is not recommended.</p></li>
446 <li><code>nonenotnull</code>
448 <p>This disables any global/inter-process Session Cache. However
449 it does force OpenSSL to send a non-null session ID to
450 accommodate buggy clients that require one.</p></li>
452 <li><code>dbm:/path/to/datafile</code>
454 <p>This makes use of a DBM hashfile on the local disk to
455 synchronize the local OpenSSL memory caches of the server
456 processes. This session cache may suffer reliability issues under
457 high load. To use this, ensure that
458 <module>mod_socache_dbm</module> is loaded.</p></li>
460 <li><code>shmcb:/path/to/datafile</code>[<code>(</code><em>size</em><code>)</code>]
462 <p>This makes use of a high-performance cyclic buffer
463 (approx. <em>size</em> bytes in size) inside a shared memory
464 segment in RAM (established via <code>/path/to/datafile</code>) to
465 synchronize the local OpenSSL memory caches of the server
466 processes. This is the recommended session cache. To use this,
467 ensure that <module>mod_socache_shmcb</module> is loaded.</p></li>
469 <li><code>dc:UNIX:/path/to/socket</code>
471 <p>This makes use of the <a
472 href="http://www.distcache.org/">distcache</a> distributed session
473 caching libraries. The argument should specify the location of
474 the server or proxy to be used using the distcache address syntax;
475 for example, <code>UNIX:/path/to/socket</code> specifies a UNIX
476 domain socket (typically a local dc_client proxy);
477 <code>IP:server.example.com:9001</code> specifies an IP
478 address. To use this, ensure that
479 <module>mod_socache_dc</module> is loaded.</p></li>
483 <example><title>Examples</title>
484 <highlight language="config">
485 SSLSessionCache dbm:/usr/local/apache/logs/ssl_gcache_data
486 SSLSessionCache shmcb:/usr/local/apache/logs/ssl_gcache_data(512000)
490 <p>The <code>ssl-cache</code> mutex is used to serialize access to
491 the session cache to prevent corruption. This mutex can be configured
492 using the <directive module="core">Mutex</directive> directive.</p>
497 <name>SSLSessionCacheTimeout</name>
498 <description>Number of seconds before an SSL session expires
499 in the Session Cache</description>
500 <syntax>SSLSessionCacheTimeout <em>seconds</em></syntax>
501 <default>SSLSessionCacheTimeout 300</default>
502 <contextlist><context>server config</context>
503 <context>virtual host</context></contextlist>
504 <compatibility>Applies also to RFC 5077 TLS session resumption in Apache 2.4.10 and later</compatibility>
508 This directive sets the timeout in seconds for the information stored in the
509 global/inter-process SSL Session Cache, the OpenSSL internal memory cache and
510 for sessions resumed by TLS session resumption (RFC 5077).
511 It can be set as low as 15 for testing, but should be set to higher
512 values like 300 in real life.</p>
513 <example><title>Example</title>
514 <highlight language="config">
515 SSLSessionCacheTimeout 600
522 <name>SSLEngine</name>
523 <description>SSL Engine Operation Switch</description>
524 <syntax>SSLEngine on|off|optional</syntax>
525 <default>SSLEngine off</default>
526 <contextlist><context>server config</context>
527 <context>virtual host</context></contextlist>
531 This directive toggles the usage of the SSL/TLS Protocol Engine. This
532 is should be used inside a <directive module="core"
533 type="section">VirtualHost</directive> section to enable SSL/TLS for a
534 that virtual host. By default the SSL/TLS Protocol Engine is
535 disabled for both the main server and all configured virtual hosts.</p>
536 <example><title>Example</title>
537 <highlight language="config">
538 <VirtualHost _default_:443>
544 <p>In Apache 2.1 and later, <directive>SSLEngine</directive> can be set to
545 <code>optional</code>. This enables support for
546 <a href="http://www.ietf.org/rfc/rfc2817.txt">RFC 2817</a>, Upgrading to TLS
547 Within HTTP/1.1. At this time no web browsers support RFC 2817.</p>
553 <description>SSL FIPS mode Switch</description>
554 <syntax>SSLFIPS on|off</syntax>
555 <default>SSLFIPS off</default>
556 <contextlist><context>server config</context></contextlist>
560 This directive toggles the usage of the SSL library FIPS_mode flag.
561 It must be set in the global server context and cannot be configured
562 with conflicting settings (SSLFIPS on followed by SSLFIPS off or
563 similar). The mode applies to all SSL library operations.
566 If httpd was compiled against an SSL library which did not support
567 the FIPS_mode flag, <code>SSLFIPS on</code> will fail. Refer to the
568 FIPS 140-2 Security Policy document of the SSL provider library for
569 specific requirements to use mod_ssl in a FIPS 140-2 approved mode
570 of operation; note that mod_ssl itself is not validated, but may be
571 described as using FIPS 140-2 validated cryptographic module, when
572 all components are assembled and operated under the guidelines imposed
573 by the applicable Security Policy.
579 <name>SSLProtocol</name>
580 <description>Configure usable SSL/TLS protocol versions</description>
581 <syntax>SSLProtocol [+|-]<em>protocol</em> ...</syntax>
582 <default>SSLProtocol all</default>
583 <contextlist><context>server config</context>
584 <context>virtual host</context></contextlist>
588 This directive can be used to control which versions of the SSL/TLS protocol
589 will be accepted in new connections.</p>
591 The available (case-insensitive) <em>protocol</em>s are:</p>
593 <li><code>SSLv3</code>
595 This is the Secure Sockets Layer (SSL) protocol, version 3.0, from
596 the Netscape Corporation.
597 It is the successor to SSLv2 and the predecessor to TLSv1.</p></li>
599 <li><code>TLSv1</code>
601 This is the Transport Layer Security (TLS) protocol, version 1.0.
602 It is the successor to SSLv3 and is defined in
603 <a href="http://www.ietf.org/rfc/rfc2246.txt">RFC 2246</a>.
604 It is supported by nearly every client.</p></li>
606 <li><code>TLSv1.1</code> (when using OpenSSL 1.0.1 and later)
608 A revision of the TLS 1.0 protocol, as defined in
609 <a href="http://www.ietf.org/rfc/rfc4346.txt">RFC 4346</a>.</p></li>
611 <li><code>TLSv1.2</code> (when using OpenSSL 1.0.1 and later)
613 A revision of the TLS 1.1 protocol, as defined in
614 <a href="http://www.ietf.org/rfc/rfc5246.txt">RFC 5246</a>.</p></li>
618 This is a shortcut for ``<code>+SSLv3 +TLSv1</code>'' or
619 - when using OpenSSL 1.0.1 and later -
620 ``<code>+SSLv3 +TLSv1 +TLSv1.1 +TLSv1.2</code>, respectively.</p></li>
622 <example><title>Example</title>
623 <highlight language="config">
631 <name>SSLCipherSuite</name>
632 <description>Cipher Suite available for negotiation in SSL
633 handshake</description>
634 <syntax>SSLCipherSuite <em>cipher-spec</em></syntax>
635 <default>SSLCipherSuite DEFAULT (depends on OpenSSL version)</default>
636 <contextlist><context>server config</context>
637 <context>virtual host</context>
638 <context>directory</context>
639 <context>.htaccess</context></contextlist>
640 <override>AuthConfig</override>
644 This complex directive uses a colon-separated <em>cipher-spec</em> string
645 consisting of OpenSSL cipher specifications to configure the Cipher Suite the
646 client is permitted to negotiate in the SSL handshake phase. Notice that this
647 directive can be used both in per-server and per-directory context. In
648 per-server context it applies to the standard SSL handshake when a connection
649 is established. In per-directory context it forces a SSL renegotiation with the
650 reconfigured Cipher Suite after the HTTP request was read but before the HTTP
651 response is sent.</p>
653 An SSL cipher specification in <em>cipher-spec</em> is composed of 4 major
654 attributes plus a few extra minor ones:</p>
656 <li><em>Key Exchange Algorithm</em>:<br />
657 RSA, Diffie-Hellman, Elliptic Curve Diffie-Hellman, Secure Remote Password
659 <li><em>Authentication Algorithm</em>:<br />
660 RSA, Diffie-Hellman, DSS, ECDSA, or none.
662 <li><em>Cipher/Encryption Algorithm</em>:<br />
663 AES, DES, Triple-DES, RC4, RC2, IDEA, etc.
665 <li><em>MAC Digest Algorithm</em>:<br />
666 MD5, SHA or SHA1, SHA256, SHA384.
669 <p>An SSL cipher can also be an export cipher. SSLv2 ciphers are no longer
670 supported. To specify which ciphers to use, one can either specify all the
671 Ciphers, one at a time, or use aliases to specify the preference and order
672 for the ciphers (see <a href="#table1">Table
673 1</a>). The actually available ciphers and aliases depends on the used
674 openssl version. Newer openssl versions may include additional ciphers.</p>
677 <columnspec><column width=".5"/><column width=".5"/></columnspec>
678 <tr><th><a name="table1">Tag</a></th> <th>Description</th></tr>
679 <tr><td colspan="2"><em>Key Exchange Algorithm:</em></td></tr>
680 <tr><td><code>kRSA</code></td> <td>RSA key exchange</td></tr>
681 <tr><td><code>kDHr</code></td> <td>Diffie-Hellman key exchange with RSA key</td></tr>
682 <tr><td><code>kDHd</code></td> <td>Diffie-Hellman key exchange with DSA key</td></tr>
683 <tr><td><code>kEDH</code></td> <td>Ephemeral (temp.key) Diffie-Hellman key exchange (no cert)</td> </tr>
684 <tr><td><code>kSRP</code></td> <td>Secure Remote Password (SRP) key exchange</td></tr>
685 <tr><td colspan="2"><em>Authentication Algorithm:</em></td></tr>
686 <tr><td><code>aNULL</code></td> <td>No authentication</td></tr>
687 <tr><td><code>aRSA</code></td> <td>RSA authentication</td></tr>
688 <tr><td><code>aDSS</code></td> <td>DSS authentication</td> </tr>
689 <tr><td><code>aDH</code></td> <td>Diffie-Hellman authentication</td></tr>
690 <tr><td colspan="2"><em>Cipher Encoding Algorithm:</em></td></tr>
691 <tr><td><code>eNULL</code></td> <td>No encryption</td> </tr>
692 <tr><td><code>NULL</code></td> <td>alias for eNULL</td> </tr>
693 <tr><td><code>AES</code></td> <td>AES encryption</td> </tr>
694 <tr><td><code>DES</code></td> <td>DES encryption</td> </tr>
695 <tr><td><code>3DES</code></td> <td>Triple-DES encryption</td> </tr>
696 <tr><td><code>RC4</code></td> <td>RC4 encryption</td> </tr>
697 <tr><td><code>RC2</code></td> <td>RC2 encryption</td> </tr>
698 <tr><td><code>IDEA</code></td> <td>IDEA encryption</td> </tr>
699 <tr><td colspan="2"><em>MAC Digest Algorithm</em>:</td></tr>
700 <tr><td><code>MD5</code></td> <td>MD5 hash function</td></tr>
701 <tr><td><code>SHA1</code></td> <td>SHA1 hash function</td></tr>
702 <tr><td><code>SHA</code></td> <td>alias for SHA1</td> </tr>
703 <tr><td><code>SHA256</code></td> <td>SHA256 hash function</td> </tr>
704 <tr><td><code>SHA384</code></td> <td>SHA384 hash function</td> </tr>
705 <tr><td colspan="2"><em>Aliases:</em></td></tr>
706 <tr><td><code>SSLv3</code></td> <td>all SSL version 3.0 ciphers</td> </tr>
707 <tr><td><code>TLSv1</code></td> <td>all TLS version 1.0 ciphers</td> </tr>
708 <tr><td><code>EXP</code></td> <td>all export ciphers</td> </tr>
709 <tr><td><code>EXPORT40</code></td> <td>all 40-bit export ciphers only</td> </tr>
710 <tr><td><code>EXPORT56</code></td> <td>all 56-bit export ciphers only</td> </tr>
711 <tr><td><code>LOW</code></td> <td>all low strength ciphers (no export, single DES)</td></tr>
712 <tr><td><code>MEDIUM</code></td> <td>all ciphers with 128 bit encryption</td> </tr>
713 <tr><td><code>HIGH</code></td> <td>all ciphers using Triple-DES</td> </tr>
714 <tr><td><code>RSA</code></td> <td>all ciphers using RSA key exchange</td> </tr>
715 <tr><td><code>DH</code></td> <td>all ciphers using Diffie-Hellman key exchange</td> </tr>
716 <tr><td><code>EDH</code></td> <td>all ciphers using Ephemeral Diffie-Hellman key exchange</td> </tr>
717 <tr><td><code>ECDH</code></td> <td>Elliptic Curve Diffie-Hellman key exchange</td> </tr>
718 <tr><td><code>ADH</code></td> <td>all ciphers using Anonymous Diffie-Hellman key exchange</td> </tr>
719 <tr><td><code>AECDH</code></td> <td>all ciphers using Anonymous Elliptic Curve Diffie-Hellman key exchange</td> </tr>
720 <tr><td><code>SRP</code></td> <td>all ciphers using Secure Remote Password (SRP) key exchange</td> </tr>
721 <tr><td><code>DSS</code></td> <td>all ciphers using DSS authentication</td> </tr>
722 <tr><td><code>ECDSA</code></td> <td>all ciphers using ECDSA authentication</td> </tr>
723 <tr><td><code>aNULL</code></td> <td>all ciphers using no authentication</td> </tr>
726 Now where this becomes interesting is that these can be put together
727 to specify the order and ciphers you wish to use. To speed this up
728 there are also aliases (<code>SSLv3, TLSv1, EXP, LOW, MEDIUM,
729 HIGH</code>) for certain groups of ciphers. These tags can be joined
730 together with prefixes to form the <em>cipher-spec</em>. Available
733 <li>none: add cipher to list</li>
734 <li><code>+</code>: move matching ciphers to the current location in list</li>
735 <li><code>-</code>: remove cipher from list (can be added later again)</li>
736 <li><code>!</code>: kill cipher from list completely (can <strong>not</strong> be added later again)</li>
740 <title><code>aNULL</code>, <code>eNULL</code> and <code>EXP</code>
741 ciphers are always disabled</title>
742 <p>Beginning with version 2.4.7, null and export-grade
743 ciphers are always disabled, as mod_ssl unconditionally prepends any supplied
744 cipher suite string with <code>!aNULL:!eNULL:!EXP:</code> at initialization.</p>
747 <p>A simpler way to look at all of this is to use the ``<code>openssl ciphers
748 -v</code>'' command which provides a nice way to successively create the
749 correct <em>cipher-spec</em> string. The default <em>cipher-spec</em> string
750 depends on the version of the OpenSSL libraries used. Let's suppose it is
751 ``<code>RC4-SHA:AES128-SHA:HIGH:MEDIUM:!aNULL:!MD5</code>'' which
752 means the following: Put <code>RC4-SHA</code> and <code>AES128-SHA</code> at
753 the beginning. We do this, because these ciphers offer a good compromise
754 between speed and security. Next, include high and medium security ciphers.
755 Finally, remove all ciphers which do not authenticate, i.e. for SSL the
756 Anonymous Diffie-Hellman ciphers, as well as all ciphers which use
757 <code>MD5</code> as hash algorithm, because it has been proven insufficient.</p>
760 $ openssl ciphers -v 'RC4-SHA:AES128-SHA:HIGH:MEDIUM:!aNULL:!MD5'
761 RC4-SHA SSLv3 Kx=RSA Au=RSA Enc=RC4(128) Mac=SHA1
762 AES128-SHA SSLv3 Kx=RSA Au=RSA Enc=AES(128) Mac=SHA1
763 DHE-RSA-AES256-SHA SSLv3 Kx=DH Au=RSA Enc=AES(256) Mac=SHA1
765 SEED-SHA SSLv3 Kx=RSA Au=RSA Enc=SEED(128) Mac=SHA1
766 PSK-RC4-SHA SSLv3 Kx=PSK Au=PSK Enc=RC4(128) Mac=SHA1
767 KRB5-RC4-SHA SSLv3 Kx=KRB5 Au=KRB5 Enc=RC4(128) Mac=SHA1
770 <p>The complete list of particular RSA & DH ciphers for SSL is given in <a
771 href="#table2">Table 2</a>.</p>
772 <example><title>Example</title>
773 <highlight language="config">
774 SSLCipherSuite RSA:!EXP:!NULL:+HIGH:+MEDIUM:-LOW
778 <columnspec><column width=".3"/><column width=".1"/><column width=".13"/>
779 <column width=".1"/><column width=".13"/><column width=".1"/>
780 <column width=".13"/></columnspec>
781 <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>
782 <tr><td colspan="7"><em>RSA Ciphers:</em></td></tr>
783 <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>
784 <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>
785 <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>
786 <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>
787 <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>
788 <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>
789 <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>
790 <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>
791 <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>
792 <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>
793 <tr><td colspan="7"><em>Diffie-Hellman Ciphers:</em></td></tr>
794 <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>
795 <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>
796 <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>
797 <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>
798 <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>
799 <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>
800 <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>
801 <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>
802 <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>
803 <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>
804 <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>
810 <name>SSLCertificateFile</name>
811 <description>Server PEM-encoded X.509 certificate data file</description>
812 <syntax>SSLCertificateFile <em>file-path</em></syntax>
813 <contextlist><context>server config</context>
814 <context>virtual host</context></contextlist>
818 This directive points to a file with certificate data in PEM format.
819 At a minimum, the file must include an end-entity (leaf) certificate.
820 Beginning with version 2.4.8, it may also include intermediate CA
821 certificates, sorted from leaf to root, and obsoletes
822 <directive module="mod_ssl">SSLCertificateChainFile</directive>.
826 Additional optional elements are DH parameters and/or an EC curve name
827 for ephemeral keys, as generated by <code>openssl dhparam</code> and
828 <code>openssl ecparam</code>, respectively (supported in version 2.4.7
829 or later) and finally, the end-entity certificate's private key.
830 If the private key is encrypted, the pass phrase dialog is forced
834 This directive can be used multiple times (referencing different filenames)
835 to support multiple algorithms for server authentication - typically
836 RSA, DSA, and ECC. The number of supported algorithms depends on the
837 OpenSSL version being used for mod_ssl: with version 1.0.0 or later,
838 <code>openssl list-public-key-algorithms</code> will output a list
839 of supported algorithms.</p>
842 When running with OpenSSL 1.0.2 or later, this directive allows
843 to configure the intermediate CA chain on a per-certificate basis,
844 which removes a limitation of the (now obsolete)
845 <directive module="mod_ssl">SSLCertificateChainFile</directive> directive.
846 DH and ECDH parameters, however, are only read from the first
847 <directive>SSLCertificateFile</directive> directive, as they
848 are applied independently of the authentication algorithm type.</p>
851 <title>DH parameter interoperability with primes > 1024 bit</title>
853 Beginning with version 2.4.7, mod_ssl makes use of
854 standardized DH parameters with prime lengths of 2048, 3072 and 4096 bits
855 and with additional prime lengths of 6144 and 8192 bits beginning with
857 (from <a href="http://www.ietf.org/rfc/rfc3526.txt">RFC 3526</a>), and hands
858 them out to clients based on the length of the certificate's RSA/DSA key.
859 With Java-based clients in particular (Java 7 or earlier), this may lead
860 to handshake failures - see this
861 <a href="../ssl/ssl_faq.html#javadh">FAQ answer</a> for working around
866 <example><title>Example</title>
867 <highlight language="config">
868 SSLCertificateFile /usr/local/apache2/conf/ssl.crt/server.crt
875 <name>SSLCertificateKeyFile</name>
876 <description>Server PEM-encoded private key file</description>
877 <syntax>SSLCertificateKeyFile <em>file-path</em></syntax>
878 <contextlist><context>server config</context>
879 <context>virtual host</context></contextlist>
883 This directive points to the PEM-encoded private key file for the
884 server (the private key may also be combined with the certificate in the
885 <directive module="mod_ssl">SSLCertificateFile</directive>, but this practice
886 is discouraged). If the contained private key is encrypted, the pass phrase
887 dialog is forced at startup time.</p>
890 The directive can be used multiple times (referencing different filenames)
891 to support multiple algorithms for server authentication. For each
892 <directive module="mod_ssl">SSLCertificateKeyFile</directive>
893 directive, there must be a matching <directive>SSLCertificateFile</directive>
896 <example><title>Example</title>
897 <highlight language="config">
898 SSLCertificateKeyFile /usr/local/apache2/conf/ssl.key/server.key
905 <name>SSLCertificateChainFile</name>
906 <description>File of PEM-encoded Server CA Certificates</description>
907 <syntax>SSLCertificateChainFile <em>file-path</em></syntax>
908 <contextlist><context>server config</context>
909 <context>virtual host</context></contextlist>
912 <note><title>SSLCertificateChainFile is deprecated</title>
913 <p><code>SSLCertificateChainFile</code> became obsolete with version 2.4.8,
914 when <directive module="mod_ssl">SSLCertificateFile</directive>
915 was extended to also load intermediate CA certificates from the server
916 certificate file.</p>
920 This directive sets the optional <em>all-in-one</em> file where you can
921 assemble the certificates of Certification Authorities (CA) which form the
922 certificate chain of the server certificate. This starts with the issuing CA
923 certificate of the server certificate and can range up to the root CA
924 certificate. Such a file is simply the concatenation of the various
925 PEM-encoded CA Certificate files, usually in certificate chain order.</p>
927 This should be used alternatively and/or additionally to <directive
928 module="mod_ssl">SSLCACertificatePath</directive> for explicitly
929 constructing the server certificate chain which is sent to the browser
930 in addition to the server certificate. It is especially useful to
931 avoid conflicts with CA certificates when using client
932 authentication. Because although placing a CA certificate of the
933 server certificate chain into <directive
934 module="mod_ssl">SSLCACertificatePath</directive> has the same effect
935 for the certificate chain construction, it has the side-effect that
936 client certificates issued by this same CA certificate are also
937 accepted on client authentication.</p>
939 But be careful: Providing the certificate chain works only if you are using a
940 <em>single</em> RSA <em>or</em> DSA based server certificate. If you are
941 using a coupled RSA+DSA certificate pair, this will work only if actually both
942 certificates use the <em>same</em> certificate chain. Else the browsers will be
943 confused in this situation.</p>
944 <example><title>Example</title>
945 <highlight language="config">
946 SSLCertificateChainFile /usr/local/apache2/conf/ssl.crt/ca.crt
953 <name>SSLCACertificatePath</name>
954 <description>Directory of PEM-encoded CA Certificates for
955 Client Auth</description>
956 <syntax>SSLCACertificatePath <em>directory-path</em></syntax>
957 <contextlist><context>server config</context>
958 <context>virtual host</context></contextlist>
962 This directive sets the directory where you keep the Certificates of
963 Certification Authorities (CAs) whose clients you deal with. These are used to
964 verify the client certificate on Client Authentication.</p>
966 The files in this directory have to be PEM-encoded and are accessed through
967 hash filenames. So usually you can't just place the Certificate files
968 there: you also have to create symbolic links named
969 <em>hash-value</em><code>.N</code>. And you should always make sure this directory
970 contains the appropriate symbolic links.</p>
971 <example><title>Example</title>
972 <highlight language="config">
973 SSLCACertificatePath /usr/local/apache2/conf/ssl.crt/
980 <name>SSLCACertificateFile</name>
981 <description>File of concatenated PEM-encoded CA Certificates
982 for Client Auth</description>
983 <syntax>SSLCACertificateFile <em>file-path</em></syntax>
984 <contextlist><context>server config</context>
985 <context>virtual host</context></contextlist>
989 This directive sets the <em>all-in-one</em> file where you can assemble the
990 Certificates of Certification Authorities (CA) whose <em>clients</em> you deal
991 with. These are used for Client Authentication. Such a file is simply the
992 concatenation of the various PEM-encoded Certificate files, in order of
993 preference. This can be used alternatively and/or additionally to
994 <directive module="mod_ssl">SSLCACertificatePath</directive>.</p>
995 <example><title>Example</title>
996 <highlight language="config">
997 SSLCACertificateFile /usr/local/apache2/conf/ssl.crt/ca-bundle-client.crt
1001 </directivesynopsis>
1004 <name>SSLCADNRequestFile</name>
1005 <description>File of concatenated PEM-encoded CA Certificates
1006 for defining acceptable CA names</description>
1007 <syntax>SSLCADNRequestFile <em>file-path</em></syntax>
1008 <contextlist><context>server config</context>
1009 <context>virtual host</context></contextlist>
1012 <p>When a client certificate is requested by mod_ssl, a list of
1013 <em>acceptable Certificate Authority names</em> is sent to the client
1014 in the SSL handshake. These CA names can be used by the client to
1015 select an appropriate client certificate out of those it has
1018 <p>If neither of the directives <directive
1019 module="mod_ssl">SSLCADNRequestPath</directive> or <directive
1020 module="mod_ssl">SSLCADNRequestFile</directive> are given, then the
1021 set of acceptable CA names sent to the client is the names of all the
1022 CA certificates given by the <directive
1023 module="mod_ssl">SSLCACertificateFile</directive> and <directive
1024 module="mod_ssl">SSLCACertificatePath</directive> directives; in other
1025 words, the names of the CAs which will actually be used to verify the
1026 client certificate.</p>
1028 <p>In some circumstances, it is useful to be able to send a set of
1029 acceptable CA names which differs from the actual CAs used to verify
1030 the client certificate - for example, if the client certificates are
1031 signed by intermediate CAs. In such cases, <directive
1032 module="mod_ssl">SSLCADNRequestPath</directive> and/or <directive
1033 module="mod_ssl">SSLCADNRequestFile</directive> can be used; the
1034 acceptable CA names are then taken from the complete set of
1035 certificates in the directory and/or file specified by this pair of
1038 <p><directive module="mod_ssl">SSLCADNRequestFile</directive> must
1039 specify an <em>all-in-one</em> file containing a concatenation of
1040 PEM-encoded CA certificates.</p>
1042 <example><title>Example</title>
1043 <highlight language="config">
1044 SSLCADNRequestFile /usr/local/apache2/conf/ca-names.crt
1048 </directivesynopsis>
1051 <name>SSLCADNRequestPath</name>
1052 <description>Directory of PEM-encoded CA Certificates for
1053 defining acceptable CA names</description>
1054 <syntax>SSLCADNRequestPath <em>directory-path</em></syntax>
1055 <contextlist><context>server config</context>
1056 <context>virtual host</context></contextlist>
1060 <p>This optional directive can be used to specify the set of
1061 <em>acceptable CA names</em> which will be sent to the client when a
1062 client certificate is requested. See the <directive
1063 module="mod_ssl">SSLCADNRequestFile</directive> directive for more
1066 <p>The files in this directory have to be PEM-encoded and are accessed
1067 through hash filenames. So usually you can't just place the
1068 Certificate files there: you also have to create symbolic links named
1069 <em>hash-value</em><code>.N</code>. And you should always make sure
1070 this directory contains the appropriate symbolic links.</p>
1071 <example><title>Example</title>
1072 <highlight language="config">
1073 SSLCADNRequestPath /usr/local/apache2/conf/ca-names.crt/
1077 </directivesynopsis>
1080 <name>SSLCARevocationPath</name>
1081 <description>Directory of PEM-encoded CA CRLs for
1082 Client Auth</description>
1083 <syntax>SSLCARevocationPath <em>directory-path</em></syntax>
1084 <contextlist><context>server config</context>
1085 <context>virtual host</context></contextlist>
1089 This directive sets the directory where you keep the Certificate Revocation
1090 Lists (CRL) of Certification Authorities (CAs) whose clients you deal with.
1091 These are used to revoke the client certificate on Client Authentication.</p>
1093 The files in this directory have to be PEM-encoded and are accessed through
1094 hash filenames. So usually you have not only to place the CRL files there.
1095 Additionally you have to create symbolic links named
1096 <em>hash-value</em><code>.rN</code>. And you should always make sure this directory
1097 contains the appropriate symbolic links.</p>
1098 <example><title>Example</title>
1099 <highlight language="config">
1100 SSLCARevocationPath /usr/local/apache2/conf/ssl.crl/
1104 </directivesynopsis>
1107 <name>SSLCARevocationFile</name>
1108 <description>File of concatenated PEM-encoded CA CRLs for
1109 Client Auth</description>
1110 <syntax>SSLCARevocationFile <em>file-path</em></syntax>
1111 <contextlist><context>server config</context>
1112 <context>virtual host</context></contextlist>
1116 This directive sets the <em>all-in-one</em> file where you can
1117 assemble the Certificate Revocation Lists (CRL) of Certification
1118 Authorities (CA) whose <em>clients</em> you deal with. These are used
1119 for Client Authentication. Such a file is simply the concatenation of
1120 the various PEM-encoded CRL files, in order of preference. This can be
1121 used alternatively and/or additionally to <directive
1122 module="mod_ssl">SSLCARevocationPath</directive>.</p>
1123 <example><title>Example</title>
1124 <highlight language="config">
1125 SSLCARevocationFile /usr/local/apache2/conf/ssl.crl/ca-bundle-client.crl
1129 </directivesynopsis>
1132 <name>SSLCARevocationCheck</name>
1133 <description>Enable CRL-based revocation checking</description>
1134 <syntax>SSLCARevocationCheck chain|leaf|none</syntax>
1135 <default>SSLCARevocationCheck none</default>
1136 <contextlist><context>server config</context>
1137 <context>virtual host</context></contextlist>
1141 Enables certificate revocation list (CRL) checking. At least one of
1142 <directive module="mod_ssl">SSLCARevocationFile</directive>
1143 or <directive module="mod_ssl">SSLCARevocationPath</directive> must be
1144 configured. When set to <code>chain</code> (recommended setting),
1145 CRL checks are applied to all certificates in the chain, while setting it to
1146 <code>leaf</code> limits the checks to the end-entity cert.
1149 <title>When set to <code>chain</code> or <code>leaf</code>,
1150 CRLs <em>must</em> be available for successful validation</title>
1152 Prior to version 2.3.15, CRL checking in mod_ssl also succeeded when
1153 no CRL(s) were found in any of the locations configured with
1154 <directive module="mod_ssl">SSLCARevocationFile</directive>
1155 or <directive module="mod_ssl">SSLCARevocationPath</directive>.
1156 With the introduction of this directive, the behavior has been changed:
1157 when checking is enabled, CRLs <em>must</em> be present for the validation
1158 to succeed - otherwise it will fail with an
1159 <code>"unable to get certificate CRL"</code> error.
1162 <example><title>Example</title>
1163 <highlight language="config">
1164 SSLCARevocationCheck chain
1168 </directivesynopsis>
1171 <name>SSLVerifyClient</name>
1172 <description>Type of Client Certificate verification</description>
1173 <syntax>SSLVerifyClient <em>level</em></syntax>
1174 <default>SSLVerifyClient none</default>
1175 <contextlist><context>server config</context>
1176 <context>virtual host</context>
1177 <context>directory</context>
1178 <context>.htaccess</context></contextlist>
1179 <override>AuthConfig</override>
1183 This directive sets the Certificate verification level for the Client
1184 Authentication. Notice that this directive can be used both in per-server and
1185 per-directory context. In per-server context it applies to the client
1186 authentication process used in the standard SSL handshake when a connection is
1187 established. In per-directory context it forces a SSL renegotiation with the
1188 reconfigured client verification level after the HTTP request was read but
1189 before the HTTP response is sent.</p>
1191 The following levels are available for <em>level</em>:</p>
1193 <li><strong>none</strong>:
1194 no client Certificate is required at all</li>
1195 <li><strong>optional</strong>:
1196 the client <em>may</em> present a valid Certificate</li>
1197 <li><strong>require</strong>:
1198 the client <em>has to</em> present a valid Certificate</li>
1199 <li><strong>optional_no_ca</strong>:
1200 the client may present a valid Certificate<br />
1201 but it need not to be (successfully) verifiable.</li>
1203 <p>In practice only levels <strong>none</strong> and
1204 <strong>require</strong> are really interesting, because level
1205 <strong>optional</strong> doesn't work with all browsers and level
1206 <strong>optional_no_ca</strong> is actually against the idea of
1207 authentication (but can be used to establish SSL test pages, etc.)</p>
1208 <example><title>Example</title>
1209 <highlight language="config">
1210 SSLVerifyClient require
1214 </directivesynopsis>
1217 <name>SSLVerifyDepth</name>
1218 <description>Maximum depth of CA Certificates in Client
1219 Certificate verification</description>
1220 <syntax>SSLVerifyDepth <em>number</em></syntax>
1221 <default>SSLVerifyDepth 1</default>
1222 <contextlist><context>server config</context>
1223 <context>virtual host</context>
1224 <context>directory</context>
1225 <context>.htaccess</context></contextlist>
1226 <override>AuthConfig</override>
1230 This directive sets how deeply mod_ssl should verify before deciding that the
1231 clients don't have a valid certificate. Notice that this directive can be
1232 used both in per-server and per-directory context. In per-server context it
1233 applies to the client authentication process used in the standard SSL
1234 handshake when a connection is established. In per-directory context it forces
1235 a SSL renegotiation with the reconfigured client verification depth after the
1236 HTTP request was read but before the HTTP response is sent.</p>
1238 The depth actually is the maximum number of intermediate certificate issuers,
1239 i.e. the number of CA certificates which are max allowed to be followed while
1240 verifying the client certificate. A depth of 0 means that self-signed client
1241 certificates are accepted only, the default depth of 1 means the client
1242 certificate can be self-signed or has to be signed by a CA which is directly
1243 known to the server (i.e. the CA's certificate is under
1244 <directive module="mod_ssl">SSLCACertificatePath</directive>), etc.</p>
1245 <example><title>Example</title>
1246 <highlight language="config">
1251 </directivesynopsis>
1254 <name>SSLSRPVerifierFile</name>
1255 <description>Path to SRP verifier file</description>
1256 <syntax>SSLSRPVerifierFile <em>file-path</em></syntax>
1257 <contextlist><context>server config</context>
1258 <context>virtual host</context></contextlist>
1259 <compatibility>Available in httpd 2.4.4 and later, if using OpenSSL 1.0.1 or
1260 later</compatibility>
1264 This directive enables TLS-SRP and sets the path to the OpenSSL SRP (Secure
1265 Remote Password) verifier file containing TLS-SRP usernames, verifiers, salts,
1266 and group parameters.</p>
1267 <example><title>Example</title>
1268 SSLSRPVerifierFile "/path/to/file.srpv"
1271 The verifier file can be created with the <code>openssl</code> command line
1273 <example><title>Creating the SRP verifier file</title>
1274 openssl srp -srpvfile passwd.srpv -userinfo "some info" -add username
1276 <p> The value given with the optional <code>-userinfo</code> parameter is
1277 avalable in the <code>SSL_SRP_USERINFO</code> request environment variable.</p>
1280 </directivesynopsis>
1283 <name>SSLSRPUnknownUserSeed</name>
1284 <description>SRP unknown user seed</description>
1285 <syntax>SSLSRPUnknownUserSeed <em>secret-string</em></syntax>
1286 <contextlist><context>server config</context>
1287 <context>virtual host</context></contextlist>
1288 <compatibility>Available in httpd 2.4.4 and later, if using OpenSSL 1.0.1 or
1289 later</compatibility>
1293 This directive sets the seed used to fake SRP user parameters for unknown
1294 users, to avoid leaking whether a given user exists. Specify a secret
1295 string. If this directive is not used, then Apache will return the
1296 UNKNOWN_PSK_IDENTITY alert to clients who specify an unknown username.
1298 <example><title>Example</title>
1299 SSLSRPUnknownUserSeed "secret"
1302 </directivesynopsis>
1305 <name>SSLOptions</name>
1306 <description>Configure various SSL engine run-time options</description>
1307 <syntax>SSLOptions [+|-]<em>option</em> ...</syntax>
1308 <contextlist><context>server config</context>
1309 <context>virtual host</context>
1310 <context>directory</context>
1311 <context>.htaccess</context></contextlist>
1312 <override>Options</override>
1316 This directive can be used to control various run-time options on a
1317 per-directory basis. Normally, if multiple <code>SSLOptions</code>
1318 could apply to a directory, then the most specific one is taken
1319 completely; the options are not merged. However if <em>all</em> the
1320 options on the <code>SSLOptions</code> directive are preceded by a
1321 plus (<code>+</code>) or minus (<code>-</code>) symbol, the options
1322 are merged. Any options preceded by a <code>+</code> are added to the
1323 options currently in force, and any options preceded by a
1324 <code>-</code> are removed from the options currently in force.</p>
1326 The available <em>option</em>s are:</p>
1328 <li><code>StdEnvVars</code>
1330 When this option is enabled, the standard set of SSL related CGI/SSI
1331 environment variables are created. This per default is disabled for
1332 performance reasons, because the information extraction step is a
1333 rather expensive operation. So one usually enables this option for
1334 CGI and SSI requests only.</p>
1336 <li><code>ExportCertData</code>
1338 When this option is enabled, additional CGI/SSI environment variables are
1339 created: <code>SSL_SERVER_CERT</code>, <code>SSL_CLIENT_CERT</code> and
1340 <code>SSL_CLIENT_CERT_CHAIN_</code><em>n</em> (with <em>n</em> = 0,1,2,..).
1341 These contain the PEM-encoded X.509 Certificates of server and client for
1342 the current HTTPS connection and can be used by CGI scripts for deeper
1343 Certificate checking. Additionally all other certificates of the client
1344 certificate chain are provided, too. This bloats up the environment a
1345 little bit which is why you have to use this option to enable it on
1348 <li><code>FakeBasicAuth</code>
1350 When this option is enabled, the Subject Distinguished Name (DN) of the
1351 Client X509 Certificate is translated into a HTTP Basic Authorization
1352 username. This means that the standard Apache authentication methods can
1353 be used for access control. The user name is just the Subject of the
1354 Client's X509 Certificate (can be determined by running OpenSSL's
1355 <code>openssl x509</code> command: <code>openssl x509 -noout -subject -in
1356 </code><em>certificate</em><code>.crt</code>). The optional <directive
1357 module="mod_ssl">SSLUserName</directive> directive can be used to
1358 specify which part of the certificate Subject is embedded in the username.
1359 Note that no password is obtained from the user. Every entry in the user
1360 file needs this password: ``<code>xxj31ZMTZzkVA</code>'', which is the
1361 DES-encrypted version of the word `<code>password</code>''. Those who
1362 live under MD5-based encryption (for instance under FreeBSD or BSD/OS,
1363 etc.) should use the following MD5 hash of the same word:
1364 ``<code>$1$OXLyS...$Owx8s2/m9/gfkcRVXzgoE/</code>''.</p>
1366 <p>Note that the <directive module="mod_auth_basic">AuthBasicFake</directive>
1367 directive within <module>mod_auth_basic</module> can be used as a more
1368 general mechanism for faking basic authentication, giving control over the
1369 structure of both the username and password.</p>
1371 <li><code>StrictRequire</code>
1373 This <em>forces</em> forbidden access when <code>SSLRequireSSL</code> or
1374 <code>SSLRequire</code> successfully decided that access should be
1375 forbidden. Usually the default is that in the case where a ``<code>Satisfy
1376 any</code>'' directive is used, and other access restrictions are passed,
1377 denial of access due to <code>SSLRequireSSL</code> or
1378 <code>SSLRequire</code> is overridden (because that's how the Apache
1379 <code>Satisfy</code> mechanism should work.) But for strict access restriction
1380 you can use <code>SSLRequireSSL</code> and/or <code>SSLRequire</code> in
1381 combination with an ``<code>SSLOptions +StrictRequire</code>''. Then an
1382 additional ``<code>Satisfy Any</code>'' has no chance once mod_ssl has
1383 decided to deny access.</p>
1385 <li><code>OptRenegotiate</code>
1387 This enables optimized SSL connection renegotiation handling when SSL
1388 directives are used in per-directory context. By default a strict
1389 scheme is enabled where <em>every</em> per-directory reconfiguration of
1390 SSL parameters causes a <em>full</em> SSL renegotiation handshake. When this
1391 option is used mod_ssl tries to avoid unnecessary handshakes by doing more
1392 granular (but still safe) parameter checks. Nevertheless these granular
1393 checks sometimes may not be what the user expects, so enable this on a
1394 per-directory basis only, please.</p>
1396 <li><code>LegacyDNStringFormat</code>
1398 This option influences how values of the
1399 <code>SSL_{CLIENT,SERVER}_{I,S}_DN</code> variables are formatted. Since
1400 version 2.3.11, Apache HTTPD uses a RFC 2253 compatible format by
1401 default. This uses commas as delimiters between the attributes, allows the
1402 use of non-ASCII characters (which are converted to UTF8), escapes
1403 various special characters with backslashes, and sorts the attributes
1404 with the "C" attribute last.</p>
1406 <p>If <code>LegacyDNStringFormat</code> is set, the old format will be
1407 used which sorts the "C" attribute first, uses slashes as separators, and
1408 does not handle non-ASCII and special characters in any consistent way.
1412 <example><title>Example</title>
1413 <highlight language="config">
1414 SSLOptions +FakeBasicAuth -StrictRequire
1415 <Files ~ "\.(cgi|shtml)$">
1416 SSLOptions +StdEnvVars -ExportCertData
1421 </directivesynopsis>
1424 <name>SSLRequireSSL</name>
1425 <description>Deny access when SSL is not used for the
1426 HTTP request</description>
1427 <syntax>SSLRequireSSL</syntax>
1428 <contextlist><context>directory</context>
1429 <context>.htaccess</context></contextlist>
1430 <override>AuthConfig</override>
1433 <p><!-- XXX: I think the syntax is wrong -->
1434 This directive forbids access unless HTTP over SSL (i.e. HTTPS) is enabled for
1435 the current connection. This is very handy inside the SSL-enabled virtual
1436 host or directories for defending against configuration errors that expose
1437 stuff that should be protected. When this directive is present all requests
1438 are denied which are not using SSL.</p>
1439 <example><title>Example</title>
1440 <highlight language="config">
1445 </directivesynopsis>
1448 <name>SSLRequire</name>
1449 <description>Allow access only when an arbitrarily complex
1450 boolean expression is true</description>
1451 <syntax>SSLRequire <em>expression</em></syntax>
1452 <contextlist><context>directory</context>
1453 <context>.htaccess</context></contextlist>
1454 <override>AuthConfig</override>
1458 <note><title>SSLRequire is deprecated</title>
1459 <p><code>SSLRequire</code> is deprecated and should in general be replaced
1460 by <a href="mod_authz_core.html#reqexpr">Require expr</a>. The so called
1461 <a href="../expr.html">ap_expr</a> syntax of <code>Require expr</code> is
1462 a superset of the syntax of <code>SSLRequire</code>, with the following
1465 <p>In <code>SSLRequire</code>, the comparison operators <code><</code>,
1466 <code><=</code>, ... are completely equivalent to the operators
1467 <code>lt</code>, <code>le</code>, ... and work in a somewhat peculiar way that
1468 first compares the length of two strings and then the lexical order.
1469 On the other hand, <a href="../expr.html">ap_expr</a> has two sets of
1470 comparison operators: The operators <code><</code>,
1471 <code><=</code>, ... do lexical string comparison, while the operators
1472 <code>-lt</code>, <code>-le</code>, ... do integer comparison.
1473 For the latter, there are also aliases without the leading dashes:
1474 <code>lt</code>, <code>le</code>, ...
1480 This directive specifies a general access requirement which has to be
1481 fulfilled in order to allow access. It is a very powerful directive because the
1482 requirement specification is an arbitrarily complex boolean expression
1483 containing any number of access checks.</p>
1485 The <em>expression</em> must match the following syntax (given as a BNF
1486 grammar notation):</p>
1489 expr ::= "<strong>true</strong>" | "<strong>false</strong>"
1490 | "<strong>!</strong>" expr
1491 | expr "<strong>&&</strong>" expr
1492 | expr "<strong>||</strong>" expr
1493 | "<strong>(</strong>" expr "<strong>)</strong>"
1496 comp ::= word "<strong>==</strong>" word | word "<strong>eq</strong>" word
1497 | word "<strong>!=</strong>" word | word "<strong>ne</strong>" word
1498 | word "<strong><</strong>" word | word "<strong>lt</strong>" word
1499 | word "<strong><=</strong>" word | word "<strong>le</strong>" word
1500 | word "<strong>></strong>" word | word "<strong>gt</strong>" word
1501 | word "<strong>>=</strong>" word | word "<strong>ge</strong>" word
1502 | word "<strong>in</strong>" "<strong>{</strong>" wordlist "<strong>}</strong>"
1503 | word "<strong>in</strong>" "<strong>PeerExtList(</strong>" word "<strong>)</strong>"
1504 | word "<strong>=~</strong>" regex
1505 | word "<strong>!~</strong>" regex
1508 | wordlist "<strong>,</strong>" word
1517 variable ::= "<strong>%{</strong>" varname "<strong>}</strong>"
1518 function ::= funcname "<strong>(</strong>" funcargs "<strong>)</strong>"
1521 <p>For <code>varname</code> any of the variables described in <a
1522 href="#envvars">Environment Variables</a> can be used. For
1523 <code>funcname</code> the available functions are listed in
1524 the <a href="../expr.html#functions">ap_expr documentation</a>.</p>
1526 <p>The <em>expression</em> is parsed into an internal machine
1527 representation when the configuration is loaded, and then evaluated
1528 during request processing. In .htaccess context, the <em>expression</em> is
1529 both parsed and executed each time the .htaccess file is encountered during
1530 request processing.</p>
1532 <example><title>Example</title>
1533 <highlight language="config">
1534 SSLRequire ( %{SSL_CIPHER} !~ m/^(EXP|NULL)-/ \
1535 and %{SSL_CLIENT_S_DN_O} eq "Snake Oil, Ltd." \
1536 and %{SSL_CLIENT_S_DN_OU} in {"Staff", "CA", "Dev"} \
1537 and %{TIME_WDAY} -ge 1 and %{TIME_WDAY} -le 5 \
1538 and %{TIME_HOUR} -ge 8 and %{TIME_HOUR} -le 20 ) \
1539 or %{REMOTE_ADDR} =~ m/^192\.76\.162\.[0-9]+$/
1543 <p>The <code>PeerExtList(<em>object-ID</em>)</code> function expects
1544 to find zero or more instances of the X.509 certificate extension
1545 identified by the given <em>object ID</em> (OID) in the client certificate.
1546 The expression evaluates to true if the left-hand side string matches
1547 exactly against the value of an extension identified with this OID.
1548 (If multiple extensions with the same OID are present, at least one
1549 extension must match).</p>
1551 <example><title>Example</title>
1552 <highlight language="config">
1553 SSLRequire "foobar" in PeerExtList("1.2.3.4.5.6")
1557 <note><title>Notes on the PeerExtList function</title>
1561 <li><p>The object ID can be specified either as a descriptive
1562 name recognized by the SSL library, such as <code>"nsComment"</code>,
1563 or as a numeric OID, such as <code>"1.2.3.4.5.6"</code>.</p></li>
1565 <li><p>Expressions with types known to the SSL library are rendered to
1566 a string before comparison. For an extension with a type not
1567 recognized by the SSL library, mod_ssl will parse the value if it is
1568 one of the primitive ASN.1 types UTF8String, IA5String, VisibleString,
1569 or BMPString. For an extension of one of these types, the string
1570 value will be converted to UTF-8 if necessary, then compared against
1571 the left-hand-side expression.</p></li>
1577 <seealso><a href="../env.html">Environment Variables in Apache HTTP Server</a>,
1578 for additional examples.
1580 <seealso><a href="mod_authz_core.html#reqexpr">Require expr</a></seealso>
1581 <seealso><a href="../expr.html">Generic expression syntax in Apache HTTP Server</a>
1583 </directivesynopsis>
1586 <name>SSLRenegBufferSize</name>
1587 <description>Set the size for the SSL renegotiation buffer</description>
1588 <syntax>SSLRenegBufferSize <var>bytes</var></syntax>
1589 <default>SSLRenegBufferSize 131072</default>
1590 <contextlist><context>directory</context>
1591 <context>.htaccess</context></contextlist>
1592 <override>AuthConfig</override>
1596 <p>If an SSL renegotiation is required in per-location context, for
1597 example, any use of <directive
1598 module="mod_ssl">SSLVerifyClient</directive> in a Directory or
1599 Location block, then <module>mod_ssl</module> must buffer any HTTP
1600 request body into memory until the new SSL handshake can be performed.
1601 This directive can be used to set the amount of memory that will be
1602 used for this buffer. </p>
1604 <note type="warning"><p>
1605 Note that in many configurations, the client sending the request body
1606 will be untrusted so a denial of service attack by consumption of
1607 memory must be considered when changing this configuration setting.
1610 <example><title>Example</title>
1611 <highlight language="config">
1612 SSLRenegBufferSize 262144
1616 </directivesynopsis>
1619 <name>SSLStrictSNIVHostCheck</name>
1620 <description>Whether to allow non-SNI clients to access a name-based virtual
1623 <syntax>SSLStrictSNIVHostCheck on|off</syntax>
1624 <default>SSLStrictSNIVHostCheck off</default>
1625 <contextlist><context>server config</context>
1626 <context>virtual host</context></contextlist>
1630 This directive sets whether a non-SNI client is allowed to access a name-based
1631 virtual host. If set to <code>on</code> in the default name-based virtual
1632 host, clients that are SNI unaware will not be allowed to access <em>any</em>
1633 virtual host, belonging to this particular IP / port combination.
1634 If set to <code>on</code> in any other virtual host, SNI unaware clients
1635 are not allowed to access this particular virtual host.
1638 <note type="warning"><p>
1639 This option is only available if httpd was compiled against an SNI capable
1643 <example><title>Example</title>
1644 <highlight language="config">
1645 SSLStrictSNIVHostCheck on
1649 </directivesynopsis>
1652 <name>SSLProxyMachineCertificatePath</name>
1653 <description>Directory of PEM-encoded client certificates and keys to be used by the proxy</description>
1654 <syntax>SSLProxyMachineCertificatePath <em>directory</em></syntax>
1655 <contextlist><context>server config</context></contextlist>
1656 <override>Not applicable</override>
1660 This directive sets the directory where you keep the certificates and
1661 keys used for authentication of the proxy server to remote servers.
1663 <p>The files in this directory must be PEM-encoded and are accessed through
1664 hash filenames. Additionally, you must create symbolic links named
1665 <code><em>hash-value</em>.N</code>. And you should always make sure this
1666 directory contains the appropriate symbolic links.</p>
1667 <note type="warning">
1668 <p>Currently there is no support for encrypted private keys</p>
1670 <example><title>Example</title>
1671 <highlight language="config">
1672 SSLProxyMachineCertificatePath /usr/local/apache2/conf/proxy.crt/
1676 </directivesynopsis>
1680 <name>SSLProxyMachineCertificateFile</name>
1681 <description>File of concatenated PEM-encoded client certificates and keys to be used by the proxy</description>
1682 <syntax>SSLProxyMachineCertificateFile <em>filename</em></syntax>
1683 <contextlist><context>server config</context></contextlist>
1684 <override>Not applicable</override>
1688 This directive sets the all-in-one file where you keep the certificates and
1689 keys used for authentication of the proxy server to remote servers.
1692 This referenced file is simply the concatenation of the various PEM-encoded
1693 certificate files, in order of preference. Use this directive alternatively
1694 or additionally to <code>SSLProxyMachineCertificatePath</code>.
1696 <note type="warning">
1697 <p>Currently there is no support for encrypted private keys</p>
1699 <example><title>Example</title>
1700 <highlight language="config">
1701 SSLProxyMachineCertificateFile /usr/local/apache2/conf/ssl.crt/proxy.pem
1705 </directivesynopsis>
1708 <name>SSLProxyMachineCertificateChainFile</name>
1709 <description>File of concatenated PEM-encoded CA certificates to be used by the proxy for choosing a certificate</description>
1710 <syntax>SSLProxyMachineCertificateChainFile <em>filename</em></syntax>
1711 <contextlist><context>server config</context></contextlist>
1712 <override>Not applicable</override>
1716 This directive sets the all-in-one file where you keep the certificate chain
1717 for all of the client certs in use. This directive will be needed if the
1718 remote server presents a list of CA certificates that are not direct signers
1719 of one of the configured client certificates.
1722 This referenced file is simply the concatenation of the various PEM-encoded
1723 certificate files. Upon startup, each client certificate configured will
1724 be examined and a chain of trust will be constructed.
1726 <note type="warning"><title>Security warning</title>
1727 <p>If this directive is enabled, all of the certificates in the file will be
1728 trusted as if they were also in <directive module="mod_ssl">
1729 SSLProxyCACertificateFile</directive>.</p>
1731 <example><title>Example</title>
1732 <highlight language="config">
1733 SSLProxyMachineCertificateChainFile /usr/local/apache2/conf/ssl.crt/proxyCA.pem
1737 </directivesynopsis>
1740 <name>SSLProxyVerify</name>
1741 <description>Type of remote server Certificate verification</description>
1742 <syntax>SSLProxyVerify <em>level</em></syntax>
1743 <default>SSLProxyVerify none</default>
1744 <contextlist><context>server config</context>
1745 <context>virtual host</context> </contextlist>
1749 <p>When a proxy is configured to forward requests to a remote SSL
1750 server, this directive can be used to configure certificate
1751 verification of the remote server. </p>
1753 The following levels are available for <em>level</em>:</p>
1755 <li><strong>none</strong>:
1756 no remote server Certificate is required at all</li>
1757 <li><strong>optional</strong>:
1758 the remote server <em>may</em> present a valid Certificate</li>
1759 <li><strong>require</strong>:
1760 the remote server <em>has to</em> present a valid Certificate</li>
1761 <li><strong>optional_no_ca</strong>:
1762 the remote server may present a valid Certificate<br />
1763 but it need not to be (successfully) verifiable.</li>
1765 <p>In practice only levels <strong>none</strong> and
1766 <strong>require</strong> are really interesting, because level
1767 <strong>optional</strong> doesn't work with all servers and level
1768 <strong>optional_no_ca</strong> is actually against the idea of
1769 authentication (but can be used to establish SSL test pages, etc.)</p>
1770 <example><title>Example</title>
1771 <highlight language="config">
1772 SSLProxyVerify require
1776 </directivesynopsis>
1779 <name>SSLProxyVerifyDepth</name>
1780 <description>Maximum depth of CA Certificates in Remote Server
1781 Certificate verification</description>
1782 <syntax>SSLProxyVerifyDepth <em>number</em></syntax>
1783 <default>SSLProxyVerifyDepth 1</default>
1784 <contextlist><context>server config</context>
1785 <context>virtual host</context> </contextlist>
1789 This directive sets how deeply mod_ssl should verify before deciding that the
1790 remote server does not have a valid certificate. </p>
1792 The depth actually is the maximum number of intermediate certificate issuers,
1793 i.e. the number of CA certificates which are max allowed to be followed while
1794 verifying the remote server certificate. A depth of 0 means that self-signed
1795 remote server certificates are accepted only, the default depth of 1 means
1796 the remote server certificate can be self-signed or has to be signed by a CA
1797 which is directly known to the server (i.e. the CA's certificate is under
1798 <directive module="mod_ssl">SSLProxyCACertificatePath</directive>), etc.</p>
1799 <example><title>Example</title>
1800 <highlight language="config">
1801 SSLProxyVerifyDepth 10
1805 </directivesynopsis>
1808 <name>SSLProxyCheckPeerExpire</name>
1809 <description>Whether to check if remote server certificate is expired
1811 <syntax>SSLProxyCheckPeerExpire on|off</syntax>
1812 <default>SSLProxyCheckPeerExpire on</default>
1813 <contextlist><context>server config</context>
1814 <context>virtual host</context></contextlist>
1818 This directive sets whether it is checked if the remote server certificate
1819 is expired or not. If the check fails a 502 status code (Bad Gateway) is
1822 <example><title>Example</title>
1823 <highlight language="config">
1824 SSLProxyCheckPeerExpire on
1828 </directivesynopsis>
1831 <name>SSLProxyCheckPeerCN</name>
1832 <description>Whether to check the remote server certificate's CN field
1834 <syntax>SSLProxyCheckPeerCN on|off</syntax>
1835 <default>SSLProxyCheckPeerCN on</default>
1836 <contextlist><context>server config</context>
1837 <context>virtual host</context></contextlist>
1841 This directive sets whether the remote server certificate's CN field is
1842 compared against the hostname of the request URL. If both are not equal
1843 a 502 status code (Bad Gateway) is sent.
1846 In 2.4.5 and later, SSLProxyCheckPeerCN has been superseded by
1847 <directive module="mod_ssl">SSLProxyCheckPeerName</directive>, and its
1848 setting is only taken into account when
1849 <code>SSLProxyCheckPeerName off</code> is specified at the same time.
1851 <example><title>Example</title>
1852 <highlight language="config">
1853 SSLProxyCheckPeerCN on
1857 </directivesynopsis>
1860 <name>SSLProxyCheckPeerName</name>
1861 <description>Configure host name checking for remote server certificates
1863 <syntax>SSLProxyCheckPeerName on|off</syntax>
1864 <default>SSLProxyCheckPeerName on</default>
1865 <contextlist><context>server config</context>
1866 <context>virtual host</context></contextlist>
1867 <compatibility>Apache HTTP Server 2.4.5 and later</compatibility>
1871 This directive configures host name checking for server certificates
1872 when mod_ssl is acting as an SSL client. The check will
1873 succeed if the host name from the request URI is found in
1874 either the subjectAltName extension or (one of) the CN attribute(s)
1875 in the certificate's subject. If the check fails, the SSL request
1876 is aborted and a 502 status code (Bad Gateway) is returned.
1877 The directive supersedes <directive module="mod_ssl">SSLProxyCheckPeerCN</directive>,
1878 which only checks for the expected host name in the first CN attribute.
1881 Wildcard matching is supported in one specific flavor: subjectAltName entries
1882 of type dNSName or CN attributes starting with <code>*.</code> will match
1883 for any DNS name with the same number of labels and the same suffix
1884 (i.e., <code>*.example.org</code> matches for <code>foo.example.org</code>,
1885 but not for <code>foo.bar.example.org</code>).
1888 </directivesynopsis>
1891 <name>SSLProxyEngine</name>
1892 <description>SSL Proxy Engine Operation Switch</description>
1893 <syntax>SSLProxyEngine on|off</syntax>
1894 <default>SSLProxyEngine off</default>
1895 <contextlist><context>server config</context>
1896 <context>virtual host</context></contextlist>
1900 This directive toggles the usage of the SSL/TLS Protocol Engine for proxy. This
1901 is usually used inside a <directive module="core"
1902 type="section">VirtualHost</directive> section to enable SSL/TLS for proxy
1903 usage in a particular virtual host. By default the SSL/TLS Protocol Engine is
1904 disabled for proxy both for the main server and all configured virtual hosts.</p>
1906 <p>Note that the SSLProxyEngine directive should not, in
1907 general, be included in a virtual host that will be acting as a
1908 forward proxy (using <Proxy> or <ProxyRequest> directives.
1909 SSLProxyEngine is not required to enable a forward proxy server to
1910 proxy SSL/TLS requests.</p>
1912 <example><title>Example</title>
1913 <highlight language="config">
1914 <VirtualHost _default_:443>
1917 </VirtualHost>
1921 </directivesynopsis>
1924 <name>SSLProxyProtocol</name>
1925 <description>Configure usable SSL protocol flavors for proxy usage</description>
1926 <syntax>SSLProxyProtocol [+|-]<em>protocol</em> ...</syntax>
1927 <default>SSLProxyProtocol all</default>
1928 <contextlist><context>server config</context>
1929 <context>virtual host</context></contextlist>
1930 <override>Options</override>
1933 <!-- XXX Why does this have an override and not .htaccess context? -->
1935 This directive can be used to control the SSL protocol flavors mod_ssl should
1936 use when establishing its server environment for proxy . It will only connect
1937 to servers using one of the provided protocols.</p>
1938 <p>Please refer to <directive module="mod_ssl">SSLProtocol</directive>
1939 for additional information.
1942 </directivesynopsis>
1945 <name>SSLProxyCipherSuite</name>
1946 <description>Cipher Suite available for negotiation in SSL
1947 proxy handshake</description>
1948 <syntax>SSLProxyCipherSuite <em>cipher-spec</em></syntax>
1949 <default>SSLProxyCipherSuite ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+EXP</default>
1950 <contextlist><context>server config</context>
1951 <context>virtual host</context>
1952 <context>directory</context>
1953 <context>.htaccess</context></contextlist>
1954 <override>AuthConfig</override>
1956 <p>Equivalent to <code>SSLCipherSuite</code>, but for the proxy connection.
1957 Please refer to <directive module="mod_ssl">SSLCipherSuite</directive>
1958 for additional information.</p>
1961 </directivesynopsis>
1963 <name>SSLProxyCACertificatePath</name>
1964 <description>Directory of PEM-encoded CA Certificates for
1965 Remote Server Auth</description>
1966 <syntax>SSLProxyCACertificatePath <em>directory-path</em></syntax>
1967 <contextlist><context>server config</context>
1968 <context>virtual host</context></contextlist>
1972 This directive sets the directory where you keep the Certificates of
1973 Certification Authorities (CAs) whose remote servers you deal with. These are used to
1974 verify the remote server certificate on Remote Server Authentication.</p>
1976 The files in this directory have to be PEM-encoded and are accessed through
1977 hash filenames. So usually you can't just place the Certificate files
1978 there: you also have to create symbolic links named
1979 <em>hash-value</em><code>.N</code>. And you should always make sure this directory
1980 contains the appropriate symbolic links.</p>
1981 <example><title>Example</title>
1982 <highlight language="config">
1983 SSLProxyCACertificatePath /usr/local/apache2/conf/ssl.crt/
1987 </directivesynopsis>
1990 <name>SSLProxyCACertificateFile</name>
1991 <description>File of concatenated PEM-encoded CA Certificates
1992 for Remote Server Auth</description>
1993 <syntax>SSLProxyCACertificateFile <em>file-path</em></syntax>
1994 <contextlist><context>server config</context>
1995 <context>virtual host</context></contextlist>
1999 This directive sets the <em>all-in-one</em> file where you can assemble the
2000 Certificates of Certification Authorities (CA) whose <em>remote servers</em> you deal
2001 with. These are used for Remote Server Authentication. Such a file is simply the
2002 concatenation of the various PEM-encoded Certificate files, in order of
2003 preference. This can be used alternatively and/or additionally to
2004 <directive module="mod_ssl">SSLProxyCACertificatePath</directive>.</p>
2005 <example><title>Example</title>
2006 <highlight language="config">
2007 SSLProxyCACertificateFile /usr/local/apache2/conf/ssl.crt/ca-bundle-remote-server.crt
2011 </directivesynopsis>
2014 <name>SSLProxyCARevocationPath</name>
2015 <description>Directory of PEM-encoded CA CRLs for
2016 Remote Server Auth</description>
2017 <syntax>SSLProxyCARevocationPath <em>directory-path</em></syntax>
2018 <contextlist><context>server config</context>
2019 <context>virtual host</context></contextlist>
2023 This directive sets the directory where you keep the Certificate Revocation
2024 Lists (CRL) of Certification Authorities (CAs) whose remote servers you deal with.
2025 These are used to revoke the remote server certificate on Remote Server Authentication.</p>
2027 The files in this directory have to be PEM-encoded and are accessed through
2028 hash filenames. So usually you have not only to place the CRL files there.
2029 Additionally you have to create symbolic links named
2030 <em>hash-value</em><code>.rN</code>. And you should always make sure this directory
2031 contains the appropriate symbolic links.</p>
2032 <example><title>Example</title>
2033 <highlight language="config">
2034 SSLProxyCARevocationPath /usr/local/apache2/conf/ssl.crl/
2038 </directivesynopsis>
2041 <name>SSLProxyCARevocationFile</name>
2042 <description>File of concatenated PEM-encoded CA CRLs for
2043 Remote Server Auth</description>
2044 <syntax>SSLProxyCARevocationFile <em>file-path</em></syntax>
2045 <contextlist><context>server config</context>
2046 <context>virtual host</context></contextlist>
2050 This directive sets the <em>all-in-one</em> file where you can
2051 assemble the Certificate Revocation Lists (CRL) of Certification
2052 Authorities (CA) whose <em>remote servers</em> you deal with. These are used
2053 for Remote Server Authentication. Such a file is simply the concatenation of
2054 the various PEM-encoded CRL files, in order of preference. This can be
2055 used alternatively and/or additionally to <directive
2056 module="mod_ssl">SSLProxyCARevocationPath</directive>.</p>
2057 <example><title>Example</title>
2058 <highlight language="config">
2059 SSLProxyCARevocationFile /usr/local/apache2/conf/ssl.crl/ca-bundle-remote-server.crl
2063 </directivesynopsis>
2066 <name>SSLProxyCARevocationCheck</name>
2067 <description>Enable CRL-based revocation checking for Remote Server Auth</description>
2068 <syntax>SSLProxyCARevocationCheck chain|leaf|none</syntax>
2069 <default>SSLProxyCARevocationCheck none</default>
2070 <contextlist><context>server config</context>
2071 <context>virtual host</context></contextlist>
2075 Enables certificate revocation list (CRL) checking for the
2076 <em>remote servers</em> you deal with. At least one of
2077 <directive module="mod_ssl">SSLProxyCARevocationFile</directive>
2078 or <directive module="mod_ssl">SSLProxyCARevocationPath</directive> must be
2079 configured. When set to <code>chain</code> (recommended setting),
2080 CRL checks are applied to all certificates in the chain, while setting it to
2081 <code>leaf</code> limits the checks to the end-entity cert.
2084 <title>When set to <code>chain</code> or <code>leaf</code>,
2085 CRLs <em>must</em> be available for successful validation</title>
2087 Prior to version 2.3.15, CRL checking in mod_ssl also succeeded when
2088 no CRL(s) were found in any of the locations configured with
2089 <directive module="mod_ssl">SSLProxyCARevocationFile</directive>
2090 or <directive module="mod_ssl">SSLProxyCARevocationPath</directive>.
2091 With the introduction of this directive, the behavior has been changed:
2092 when checking is enabled, CRLs <em>must</em> be present for the validation
2093 to succeed - otherwise it will fail with an
2094 <code>"unable to get certificate CRL"</code> error.
2097 <example><title>Example</title>
2098 <highlight language="config">
2099 SSLProxyCARevocationCheck chain
2103 </directivesynopsis>
2106 <name>SSLUserName</name>
2107 <description>Variable name to determine user name</description>
2108 <syntax>SSLUserName <em>varname</em></syntax>
2109 <contextlist><context>server config</context>
2110 <context>directory</context>
2111 <context>.htaccess</context></contextlist>
2112 <override>AuthConfig</override>
2116 This directive sets the "user" field in the Apache request object.
2117 This is used by lower modules to identify the user with a character
2118 string. In particular, this may cause the environment variable
2119 <code>REMOTE_USER</code> to be set. The <em>varname</em> can be
2120 any of the <a href="#envvars">SSL environment variables</a>.</p>
2122 <p>When the <code>FakeBasicAuth</code> option is enabled, this directive
2123 instead controls the value of the username embedded within the basic
2124 authentication header (see <a href="#ssloptions">SSLOptions</a>).</p>
2126 <example><title>Example</title>
2127 <highlight language="config">
2128 SSLUserName SSL_CLIENT_S_DN_CN
2132 </directivesynopsis>
2135 <name>SSLHonorCipherOrder</name>
2136 <description>Option to prefer the server's cipher preference order</description>
2137 <syntax>SSLHonorCipherOrder on|off</syntax>
2138 <default>SSLHonorCipherOrder off</default>
2139 <contextlist><context>server config</context>
2140 <context>virtual host</context></contextlist>
2143 <p>When choosing a cipher during an SSLv3 or TLSv1 handshake, normally
2144 the client's preference is used. If this directive is enabled, the
2145 server's preference will be used instead.</p>
2146 <example><title>Example</title>
2147 <highlight language="config">
2148 SSLHonorCipherOrder on
2152 </directivesynopsis>
2155 <name>SSLCryptoDevice</name>
2156 <description>Enable use of a cryptographic hardware accelerator</description>
2157 <syntax>SSLCryptoDevice <em>engine</em></syntax>
2158 <default>SSLCryptoDevice builtin</default>
2159 <contextlist><context>server config</context></contextlist>
2163 This directive enables use of a cryptographic hardware accelerator
2164 board to offload some of the SSL processing overhead. This directive
2165 can only be used if the SSL toolkit is built with "engine" support;
2166 OpenSSL 0.9.7 and later releases have "engine" support by default, the
2167 separate "-engine" releases of OpenSSL 0.9.6 must be used.</p>
2169 <p>To discover which engine names are supported, run the command
2170 "<code>openssl engine</code>".</p>
2172 <example><title>Example</title>
2173 <highlight language="config">
2174 # For a Broadcom accelerator:
2175 SSLCryptoDevice ubsec
2179 </directivesynopsis>
2182 <name>SSLOCSPEnable</name>
2183 <description>Enable OCSP validation of the client certificate chain</description>
2184 <syntax>SSLOCSPEnable on|off</syntax>
2185 <default>SSLOCSPEnable off</default>
2186 <contextlist><context>server config</context>
2187 <context>virtual host</context></contextlist>
2190 <p>This option enables OCSP validation of the client certificate
2191 chain. If this option is enabled, certificates in the client's
2192 certificate chain will be validated against an OCSP responder after
2193 normal verification (including CRL checks) have taken place.</p>
2195 <p>The OCSP responder used is either extracted from the certificate
2196 itself, or derived by configuration; see the
2197 <directive module="mod_ssl">SSLOCSPDefaultResponder</directive> and
2198 <directive module="mod_ssl">SSLOCSPOverrideResponder</directive>
2201 <example><title>Example</title>
2202 <highlight language="config">
2205 SSLOCSPDefaultResponder http://responder.example.com:8888/responder
2206 SSLOCSPOverrideResponder on
2210 </directivesynopsis>
2213 <name>SSLOCSPDefaultResponder</name>
2214 <description>Set the default responder URI for OCSP validation</description>
2215 <syntax>SSLOCSDefaultResponder <em>uri</em></syntax>
2216 <contextlist><context>server config</context>
2217 <context>virtual host</context></contextlist>
2220 <p>This option sets the default OCSP responder to use. If <directive
2221 module="mod_ssl">SSLOCSPOverrideResponder</directive> is not enabled,
2222 the URI given will be used only if no responder URI is specified in
2223 the certificate being verified.</p>
2225 </directivesynopsis>
2228 <name>SSLOCSPOverrideResponder</name>
2229 <description>Force use of the default responder URI for OCSP validation</description>
2230 <syntax>SSLOCSPOverrideResponder on|off</syntax>
2231 <default>SSLOCSPOverrideResponder off</default>
2232 <contextlist><context>server config</context>
2233 <context>virtual host</context></contextlist>
2236 <p>This option forces the configured default OCSP responder to be used
2237 during OCSP certificate validation, regardless of whether the
2238 certificate being validated references an OCSP responder.</p>
2240 </directivesynopsis>
2243 <name>SSLOCSPResponseTimeSkew</name>
2244 <description>Maximum allowable time skew for OCSP response validation</description>
2245 <syntax>SSLOCSPResponseTimeSkew <em>seconds</em></syntax>
2246 <default>SSLOCSPResponseTimeSkew 300</default>
2247 <contextlist><context>server config</context>
2248 <context>virtual host</context></contextlist>
2251 <p>This option sets the maximum allowable time skew for OCSP responses
2252 (when checking their <code>thisUpdate</code> and <code>nextUpdate</code> fields).</p>
2254 </directivesynopsis>
2257 <name>SSLOCSPResponseMaxAge</name>
2258 <description>Maximum allowable age for OCSP responses</description>
2259 <syntax>SSLOCSPResponseMaxAge <em>seconds</em></syntax>
2260 <default>SSLOCSPResponseMaxAge -1</default>
2261 <contextlist><context>server config</context>
2262 <context>virtual host</context></contextlist>
2265 <p>This option sets the maximum allowable age ("freshness") for OCSP responses.
2266 The default value (<code>-1</code>) does not enforce a maximum age,
2267 which means that OCSP responses are considered valid as long as their
2268 <code>nextUpdate</code> field is in the future.</p>
2270 </directivesynopsis>
2273 <name>SSLOCSPResponderTimeout</name>
2274 <description>Timeout for OCSP queries</description>
2275 <syntax>SSLOCSPResponderTimeout <em>seconds</em></syntax>
2276 <default>SSLOCSPResponderTimeout 10</default>
2277 <contextlist><context>server config</context>
2278 <context>virtual host</context></contextlist>
2281 <p>This option sets the timeout for queries to OCSP responders, when
2282 <directive module="mod_ssl">SSLOCSPEnable</directive> is turned on.</p>
2284 </directivesynopsis>
2287 <name>SSLOCSPUseRequestNonce</name>
2288 <description>Use a nonce within OCSP queries</description>
2289 <syntax>SSLOCSPUseRequestNonce on|off</syntax>
2290 <default>SSLOCSPUseRequestNonce on</default>
2291 <contextlist><context>server config</context>
2292 <context>virtual host</context></contextlist>
2293 <compatibility>Available in httpd 2.4.10 and later</compatibility>
2296 <p>This option determines whether queries to OCSP responders should contain
2297 a nonce or not. By default, a query nonce is always used and checked against
2298 the response's one. When the responder does not use nonces (e.g. Microsoft OCSP
2299 Responder), this option should be turned <code>off</code>.</p>
2301 </directivesynopsis>
2304 <name>SSLInsecureRenegotiation</name>
2305 <description>Option to enable support for insecure renegotiation</description>
2306 <syntax>SSLInsecureRenegotiation on|off</syntax>
2307 <default>SSLInsecureRenegotiation off</default>
2308 <contextlist><context>server config</context>
2309 <context>virtual host</context></contextlist>
2310 <compatibility>Available if using OpenSSL 0.9.8m or later</compatibility>
2313 <p>As originally specified, all versions of the SSL and TLS protocols
2314 (up to and including TLS/1.2) were vulnerable to a Man-in-the-Middle
2316 (<a href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2009-3555">CVE-2009-3555</a>)
2317 during a renegotiation. This vulnerability allowed an attacker to
2318 "prefix" a chosen plaintext to the HTTP request as seen by the web
2319 server. A protocol extension was developed which fixed this
2320 vulnerability if supported by both client and server.</p>
2322 <p>If <module>mod_ssl</module> is linked against OpenSSL version 0.9.8m
2323 or later, by default renegotiation is only supported with
2324 clients supporting the new protocol extension. If this directive is
2325 enabled, renegotiation will be allowed with old (unpatched) clients,
2326 albeit insecurely.</p>
2328 <note type="warning"><title>Security warning</title>
2329 <p>If this directive is enabled, SSL connections will be vulnerable to
2330 the Man-in-the-Middle prefix attack as described
2331 in <a href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2009-3555">CVE-2009-3555</a>.</p>
2334 <example><title>Example</title>
2335 <highlight language="config">
2336 SSLInsecureRenegotiation on
2340 <p>The <code>SSL_SECURE_RENEG</code> environment variable can be used
2341 from an SSI or CGI script to determine whether secure renegotiation is
2342 supported for a given SSL connection.</p>
2345 </directivesynopsis>
2348 <name>SSLUseStapling</name>
2349 <description>Enable stapling of OCSP responses in the TLS handshake</description>
2350 <syntax>SSLUseStapling on|off</syntax>
2351 <default>SSLUseStapling off</default>
2352 <contextlist><context>server config</context>
2353 <context>virtual host</context></contextlist>
2354 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2357 <p>This option enables OCSP stapling, as defined by the "Certificate
2358 Status Request" TLS extension specified in RFC 6066. If enabled (and
2359 requested by the client), mod_ssl will include an OCSP response
2360 for its own certificate in the TLS handshake. Configuring an
2361 <directive module="mod_ssl">SSLStaplingCache</directive> is a
2362 prerequisite for enabling OCSP stapling.</p>
2364 <p>OCSP stapling relieves the client of querying the OCSP responder
2365 on its own, but it should be noted that with the RFC 6066 specification,
2366 the server's <code>CertificateStatus</code> reply may only include an
2367 OCSP response for a single cert. For server certificates with intermediate
2368 CA certificates in their chain (the typical case nowadays),
2369 stapling in its current implementation therefore only partially achieves the
2370 stated goal of "saving roundtrips and resources" - see also
2371 <a href="http://www.ietf.org/rfc/rfc6961.txt">RFC 6961</a>
2372 (TLS Multiple Certificate Status Extension).
2375 </directivesynopsis>
2378 <name>SSLStaplingCache</name>
2379 <description>Configures the OCSP stapling cache</description>
2380 <syntax>SSLStaplingCache <em>type</em></syntax>
2381 <contextlist><context>server config</context></contextlist>
2382 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2385 <p>Configures the cache used to store OCSP responses which get included
2386 in the TLS handshake if <directive module="mod_ssl">SSLUseStapling</directive>
2387 is enabled. Configuration of a cache is mandatory for OCSP stapling.
2388 With the exception of <code>none</code> and <code>nonenotnull</code>,
2389 the same storage types are supported as with
2390 <directive module="mod_ssl">SSLSessionCache</directive>.</p>
2392 <p>The <code>ssl-stapling</code> mutex is used to serialize access to the
2393 OCSP stapling cache to prevent corruption. This mutex can be configured
2394 using the <directive module="core">Mutex</directive> directive.</p>
2396 </directivesynopsis>
2399 <name>SSLStaplingResponseTimeSkew</name>
2400 <description>Maximum allowable time skew for OCSP stapling response validation</description>
2401 <syntax>SSLStaplingResponseTimeSkew <em>seconds</em></syntax>
2402 <default>SSLStaplingResponseTimeSkew 300</default>
2403 <contextlist><context>server config</context>
2404 <context>virtual host</context></contextlist>
2405 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2408 <p>This option sets the maximum allowable time skew when mod_ssl checks the
2409 <code>thisUpdate</code> and <code>nextUpdate</code> fields of OCSP responses
2410 which get included in the TLS handshake (OCSP stapling). Only applicable
2411 if <directive module="mod_ssl">SSLUseStapling</directive> is turned on.</p>
2413 </directivesynopsis>
2416 <name>SSLStaplingResponderTimeout</name>
2417 <description>Timeout for OCSP stapling queries</description>
2418 <syntax>SSLStaplingResponderTimeout <em>seconds</em></syntax>
2419 <default>SSLStaplingResponderTimeout 10</default>
2420 <contextlist><context>server config</context>
2421 <context>virtual host</context></contextlist>
2422 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2425 <p>This option sets the timeout for queries to OCSP responders when
2426 <directive module="mod_ssl">SSLUseStapling</directive> is enabled
2427 and mod_ssl is querying a responder for OCSP stapling purposes.</p>
2429 </directivesynopsis>
2432 <name>SSLStaplingResponseMaxAge</name>
2433 <description>Maximum allowable age for OCSP stapling responses</description>
2434 <syntax>SSLStaplingResponseMaxAge <em>seconds</em></syntax>
2435 <default>SSLStaplingResponseMaxAge -1</default>
2436 <contextlist><context>server config</context>
2437 <context>virtual host</context></contextlist>
2438 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2441 <p>This option sets the maximum allowable age ("freshness") when
2442 considering OCSP responses for stapling purposes, i.e. when
2443 <directive module="mod_ssl">SSLUseStapling</directive> is turned on.
2444 The default value (<code>-1</code>) does not enforce a maximum age,
2445 which means that OCSP responses are considered valid as long as their
2446 <code>nextUpdate</code> field is in the future.</p>
2448 </directivesynopsis>
2451 <name>SSLStaplingStandardCacheTimeout</name>
2452 <description>Number of seconds before expiring responses in the OCSP stapling cache</description>
2453 <syntax>SSLStaplingStandardCacheTimeout <em>seconds</em></syntax>
2454 <default>SSLStaplingStandardCacheTimeout 3600</default>
2455 <contextlist><context>server config</context>
2456 <context>virtual host</context></contextlist>
2457 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2460 <p>Sets the timeout in seconds before responses in the OCSP stapling cache
2461 (configured through <directive module="mod_ssl">SSLStaplingCache</directive>)
2462 will expire. This directive applies to <em>valid</em> responses, while
2463 <directive module="mod_ssl">SSLStaplingErrorCacheTimeout</directive> is
2464 used for controlling the timeout for invalid/unavailable responses.
2467 </directivesynopsis>
2470 <name>SSLStaplingReturnResponderErrors</name>
2471 <description>Pass stapling related OCSP errors on to client</description>
2472 <syntax>SSLStaplingReturnResponderErrors on|off</syntax>
2473 <default>SSLStaplingReturnResponderErrors on</default>
2474 <contextlist><context>server config</context>
2475 <context>virtual host</context></contextlist>
2476 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2479 <p>When enabled, mod_ssl will pass responses from unsuccessful
2480 stapling related OCSP queries (such as status errors, expired responses etc.)
2481 on to the client. If set to <code>off</code>, no stapled responses
2482 for failed queries will be included in the TLS handshake.</p>
2484 </directivesynopsis>
2487 <name>SSLStaplingFakeTryLater</name>
2488 <description>Synthesize "tryLater" responses for failed OCSP stapling queries</description>
2489 <syntax>SSLStaplingFakeTryLater on|off</syntax>
2490 <default>SSLStaplingFakeTryLater on</default>
2491 <contextlist><context>server config</context>
2492 <context>virtual host</context></contextlist>
2493 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2496 <p>When enabled and a query to an OCSP responder for stapling
2497 purposes fails, mod_ssl will synthesize a "tryLater" response for the
2498 client. Only effective if <directive
2499 module="mod_ssl">SSLStaplingReturnResponderErrors</directive>
2500 is also enabled.</p>
2502 </directivesynopsis>
2505 <name>SSLStaplingErrorCacheTimeout</name>
2506 <description>Number of seconds before expiring invalid responses in the OCSP stapling cache</description>
2507 <syntax>SSLStaplingErrorCacheTimeout <em>seconds</em></syntax>
2508 <default>SSLStaplingErrorCacheTimeout 600</default>
2509 <contextlist><context>server config</context>
2510 <context>virtual host</context></contextlist>
2511 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2514 <p>Sets the timeout in seconds before <em>invalid</em> responses
2515 in the OCSP stapling cache (configured through <directive
2516 module="mod_ssl">SSLStaplingCache</directive>) will expire.
2517 To set the cache timeout for valid responses, see
2518 <directive module="mod_ssl">SSLStaplingStandardCacheTimeout</directive>.</p>
2520 </directivesynopsis>
2523 <name>SSLStaplingForceURL</name>
2524 <description>Override the OCSP responder URI specified in the certificate's AIA extension</description>
2525 <syntax>SSLStaplingForceURL <em>uri</em></syntax>
2526 <contextlist><context>server config</context>
2527 <context>virtual host</context></contextlist>
2528 <compatibility>Available if using OpenSSL 0.9.8h or later</compatibility>
2531 <p>This directive overrides the URI of an OCSP responder as obtained from
2532 the authorityInfoAccess (AIA) extension of the certificate.
2533 One potential use is when a proxy is used for retrieving OCSP queries.</p>
2535 </directivesynopsis>
2538 <name>SSLSessionTicketKeyFile</name>
2539 <description>Persistent encryption/decryption key for TLS session tickets</description>
2540 <syntax>SSLSessionTicketKeyFile <em>file-path</em></syntax>
2541 <contextlist><context>server config</context>
2542 <context>virtual host</context></contextlist>
2543 <compatibility>Available in httpd 2.4.0 and later, if using OpenSSL 0.9.8h or later</compatibility>
2546 <p>Optionally configures a secret key for encrypting and decrypting
2547 TLS session tickets, as defined in
2548 <a href="http://www.ietf.org/rfc/rfc5077.txt">RFC 5077</a>.
2549 Primarily suitable for clustered environments where TLS sessions information
2550 should be shared between multiple nodes. For single-instance httpd setups,
2551 it is recommended to <em>not</em> configure a ticket key file, but to
2552 rely on (random) keys generated by mod_ssl at startup, instead.</p>
2553 <p>The ticket key file must contain 48 bytes of random data,
2554 preferrably created from a high-entropy source. On a Unix-based system,
2555 a ticket key file can be created as follows:</p>
2558 dd if=/dev/random of=/path/to/file.tkey bs=1 count=48
2561 <p>Ticket keys should be rotated (replaced) on a frequent basis,
2562 as this is the only way to invalidate an existing session ticket -
2563 OpenSSL currently doesn't allow to specify a limit for ticket lifetimes.</p>
2565 <note type="warning">
2566 <p>The ticket key file contains sensitive keying material and should
2567 be protected with file permissions similar to those used for
2568 <directive module="mod_ssl">SSLCertificateKeyFile</directive>.</p>
2571 </directivesynopsis>
2574 <name>SSLCompression</name>
2575 <description>Enable compression on the SSL level</description>
2576 <syntax>SSLCompression on|off</syntax>
2577 <default>SSLCompression off</default>
2578 <contextlist><context>server config</context>
2579 <context>virtual host</context></contextlist>
2580 <compatibility>Available in httpd 2.4.3 and later, if using OpenSSL 0.9.8 or later;
2581 virtual host scope available if using OpenSSL 1.0.0 or later.
2582 The default used to be <code>on</code> in version 2.4.3.</compatibility>
2585 <p>This directive allows to enable compression on the SSL level.</p>
2586 <note type="warning">
2587 <p>Enabling compression causes security issues in most setups (the so called
2591 </directivesynopsis>
2594 <name>SSLSessionTickets</name>
2595 <description>Enable or disable use of TLS session tickets</description>
2596 <syntax>SSLSessionTickets on|off</syntax>
2597 <default>SSLSessionTickets on</default>
2598 <contextlist><context>server config</context>
2599 <context>virtual host</context></contextlist>
2600 <compatibility>Available in httpd 2.4.11 and later, if using OpenSSL 0.9.8f
2601 or later.</compatibility>
2604 <p>This directive allows to enable or disable the use of TLS session tickets
2606 <note type="warning">
2607 <p>TLS session tickets are enabled by default. Using them without restarting
2608 the web server with an appropriate frequency (e.g. daily) compromises perfect
2609 forward secrecy.</p>
2612 </directivesynopsis>
2615 <name>SSLOpenSSLConfCmd</name>
2616 <description>Configure OpenSSL parameters through its <em>SSL_CONF</em> API</description>
2617 <syntax>SSLOpenSSLConfCmd <em>command-name</em> <em>command-value</em></syntax>
2618 <contextlist><context>server config</context>
2619 <context>virtual host</context></contextlist>
2620 <compatibility>Available in httpd 2.4.8 and later, if using OpenSSL 1.0.2 or later</compatibility>
2623 <p>This directive exposes OpenSSL's <em>SSL_CONF</em> API to mod_ssl,
2624 allowing a flexible configuration of OpenSSL parameters without the need
2625 of implementing additional <module>mod_ssl</module> directives when new
2626 features are added to OpenSSL.</p>
2628 <p>The set of available <directive>SSLOpenSSLConfCmd</directive> commands
2629 depends on the OpenSSL version being used for <module>mod_ssl</module>
2630 (at least version 1.0.2 is required). For a list of supported command
2631 names, see the section <em>Supported configuration file commands</em> in the
2632 <a href="http://www.openssl.org/docs/ssl/SSL_CONF_cmd.html#supported_configuration_file_commands">SSL_CONF_cmd(3)</a> manual page for OpenSSL.</p>
2634 <p>Some of the <directive>SSLOpenSSLConfCmd</directive> commands can be used
2635 as an alternative to existing directives (such as
2636 <directive module="mod_ssl">SSLCipherSuite</directive> or
2637 <directive module="mod_ssl">SSLProtocol</directive>),
2638 though it should be noted that the syntax / allowable values for the parameters
2639 may sometimes differ.</p>
2641 <example><title>Examples</title>
2642 <highlight language="config">
2643 SSLOpenSSLConfCmd Options -SessionTicket,ServerPreference
2644 SSLOpenSSLConfCmd ECDHParameters brainpoolP256r1
2645 SSLOpenSSLConfCmd ServerInfoFile /usr/local/apache2/conf/server-info.pem
2646 SSLOpenSSLConfCmd Protocol "-ALL, TLSv1.2"
2647 SSLOpenSSLConfCmd SignatureAlgorithms RSA+SHA384:ECDSA+SHA256
2651 </directivesynopsis>