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<modulesynopsis metafile="mod_ssl.xml.meta">

<name>mod_ssl</name>

<description>Strong cryptography using the Secure Sockets

Layer (SSL) and Transport Layer Security (TLS) protocols</description>

<status>Extension</status>

<sourcefile>mod_ssl.c</sourcefile>

<identifier>ssl_module</identifier>

<summary>

<p>This module provides SSL v2/v3 and TLS v1 support for the Apache

HTTP Server. It was contributed by Ralf S. Engelschall based on his

mod_ssl project and originally derived from work by Ben Laurie.</p>

<p>This module relies on <a href="http://www.openssl.org/">OpenSSL</a>

to provide the cryptography engine.</p>

<p>Further details, discussion, and examples are provided in the

<a href="/ssl/">SSL documentation</a>.</p>

</summary>

<section id="envvars"><title>Environment Variables</title>

<p>This module can be configured to provide several items of SSL information

as additional environment variables to the SSI and CGI namespace. This

information is not provided by default for performance reasons. (See

<directive>SSLOptions</directive> StdEnvVars, below.) The generated variables

are listed in the table below. For backward compatibility the information can

be made available under different names, too. Look in the <a

href="/ssl/ssl_compat.html">Compatibility</a> chapter for details on the

compatibility variables.</p>

<table border="1">

<columnspec><column width=".3"/><column width=".2"/><column width=".5"/>

</columnspec>

<tr>

<th><a name="table3">Variable Name:</a></th>

<th>Value Type:</th>

<th>Description:</th>

</tr>

<tr><td><code>HTTPS</code></td> <td>flag</td> <td>HTTPS is being used.</td></tr>

<tr><td><code>SSL_PROTOCOL</code></td> <td>string</td> <td>The SSL protocol version (SSLv3, TLSv1, TLSv1.1, TLSv1.2)</td></tr>

<tr><td><code>SSL_SESSION_ID</code></td> <td>string</td> <td>The hex-encoded SSL session id</td></tr>

<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>

<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>

<tr><td><code>SSL_CIPHER</code></td> <td>string</td> <td>The cipher specification name</td></tr>

<tr><td><code>SSL_CIPHER_EXPORT</code></td> <td>string</td> <td><code>true</code> if cipher is an export cipher</td></tr>

<tr><td><code>SSL_CIPHER_USEKEYSIZE</code></td> <td>number</td> <td>Number of cipher bits (actually used)</td></tr>

<tr><td><code>SSL_CIPHER_ALGKEYSIZE</code></td> <td>number</td> <td>Number of cipher bits (possible)</td></tr>

<tr><td><code>SSL_COMPRESS_METHOD</code></td> <td>string</td> <td>SSL compression method negotiated</td></tr>

<tr><td><code>SSL_VERSION_INTERFACE</code></td> <td>string</td> <td>The mod_ssl program version</td></tr>

<tr><td><code>SSL_VERSION_LIBRARY</code></td> <td>string</td> <td>The OpenSSL program version</td></tr>

<tr><td><code>SSL_CLIENT_M_VERSION</code></td> <td>string</td> <td>The version of the client certificate</td></tr>

<tr><td><code>SSL_CLIENT_M_SERIAL</code></td> <td>string</td> <td>The serial of the client certificate</td></tr>

<tr><td><code>SSL_CLIENT_S_DN</code></td> <td>string</td> <td>Subject DN in client's certificate</td></tr>

<tr><td><code>SSL_CLIENT_S_DN_</code><em>x509</em></td> <td>string</td> <td>Component of client's Subject DN</td></tr>

<tr><td><code>SSL_CLIENT_I_DN</code></td> <td>string</td> <td>Issuer DN of client's certificate</td></tr>

<tr><td><code>SSL_CLIENT_I_DN_</code><em>x509</em></td> <td>string</td> <td>Component of client's Issuer DN</td></tr>

<tr><td><code>SSL_CLIENT_V_START</code></td> <td>string</td> <td>Validity of client's certificate (start time)</td></tr>

<tr><td><code>SSL_CLIENT_V_END</code></td> <td>string</td> <td>Validity of client's certificate (end time)</td></tr>

<tr><td><code>SSL_CLIENT_V_REMAIN</code></td> <td>string</td> <td>Number of days until client's certificate expires</td></tr>

<tr><td><code>SSL_CLIENT_A_SIG</code></td> <td>string</td> <td>Algorithm used for the signature of client's certificate</td></tr>

<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>

<tr><td><code>SSL_CLIENT_CERT</code></td> <td>string</td> <td>PEM-encoded client certificate</td></tr>

<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>

<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>

<tr><td><code>SSL_SERVER_M_VERSION</code></td> <td>string</td> <td>The version of the server certificate</td></tr>

<tr><td><code>SSL_SERVER_M_SERIAL</code></td> <td>string</td> <td>The serial of the server certificate</td></tr>

<tr><td><code>SSL_SERVER_S_DN</code></td> <td>string</td> <td>Subject DN in server's certificate</td></tr>

<tr><td><code>SSL_SERVER_S_DN_</code><em>x509</em></td> <td>string</td> <td>Component of server's Subject DN</td></tr>

<tr><td><code>SSL_SERVER_I_DN</code></td> <td>string</td> <td>Issuer DN of server's certificate</td></tr>

<tr><td><code>SSL_SERVER_I_DN_</code><em>x509</em></td> <td>string</td> <td>Component of server's Issuer DN</td></tr>

<tr><td><code>SSL_SERVER_V_START</code></td> <td>string</td> <td>Validity of server's certificate (start time)</td></tr>

<tr><td><code>SSL_SERVER_V_END</code></td> <td>string</td> <td>Validity of server's certificate (end time)</td></tr>

<tr><td><code>SSL_SERVER_A_SIG</code></td> <td>string</td> <td>Algorithm used for the signature of server's certificate</td></tr>

<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>

<tr><td><code>SSL_SERVER_CERT</code></td> <td>string</td> <td>PEM-encoded server certificate</td></tr>

</table>

<p><em>x509</em> specifies a component of an X.509 DN; one of

<code>C,ST,L,O,OU,CN,T,I,G,S,D,UID,Email</code>. In Apache 2.1 and

later, <em>x509</em> may also include a numeric <code>_n</code>

suffix. If the DN in question contains multiple attributes of the

same name, this suffix is used as a zero-based index to select a

particular attribute. For example, where the server certificate

subject DN included two OU attributes, <code>SSL_SERVER_S_DN_OU_0</code>

and

<code>SSL_SERVER_S_DN_OU_1</code> could be used to reference each. A

variable name without a <code>_n</code> suffix is equivalent to that

name with a <code>_0</code> suffix; the first (or only) attribute.

When the environment table is populated using

the <code>StdEnvVars</code> option of

the <directive module="mod_ssl">SSLOptions</directive> directive, the

first (or only) attribute of any DN is added only under a non-suffixed

name; i.e. no <code>_0</code> suffixed entries are added.</p>

<p>The format of the <em>*_DN</em> variables has changed in Apache HTTPD

2.3.11. See the <code>LegacyDNStringFormat</code> option for

<directive module="mod_ssl">SSLOptions</directive> for details.</p>

<p><code>SSL_CLIENT_V_REMAIN</code> is only available in version 2.1

and later.</p>

<p>A number of additional environment variables can also be used

in <directive>SSLRequire</directive> expressions, or in custom log

formats:</p>

<note><pre>HTTP_USER_AGENT PATH_INFO AUTH_TYPE

HTTP_REFERER QUERY_STRING SERVER_SOFTWARE

HTTP_COOKIE REMOTE_HOST API_VERSION

HTTP_FORWARDED REMOTE_IDENT TIME_YEAR

HTTP_HOST IS_SUBREQ TIME_MON

HTTP_PROXY_CONNECTION DOCUMENT_ROOT TIME_DAY

HTTP_ACCEPT SERVER_ADMIN TIME_HOUR

THE_REQUEST SERVER_NAME TIME_MIN

REQUEST_FILENAME SERVER_PORT TIME_SEC

REQUEST_METHOD SERVER_PROTOCOL TIME_WDAY

REQUEST_SCHEME REMOTE_ADDR TIME

REQUEST_URI REMOTE_USER</pre></note>

<p>In these contexts, two special formats can also be used:</p>

<dl>

<dt><code>ENV:<em>variablename</em></code></dt>

<dd>This will expand to the standard environment

variable <em>variablename</em>.</dd>

<dt><code>HTTP:<em>headername</em></code></dt>

<dd>This will expand to the value of the request header with name

<em>headername</em>.</dd>

</dl>

</section>

<section id="logformats"><title>Custom Log Formats</title>

<p>When <module>mod_ssl</module> is built into Apache or at least

loaded (under DSO situation) additional functions exist for the <a

href="mod_log_config.html#formats">Custom Log Format</a> of

<module>mod_log_config</module>. First there is an

additional ``<code>%{</code><em>varname</em><code>}x</code>''

eXtension format function which can be used to expand any variables

provided by any module, especially those provided by mod_ssl which can

you find in the above table.</p>

<p>

For backward compatibility there is additionally a special

``<code>%{</code><em>name</em><code>}c</code>'' cryptography format function

provided. Information about this function is provided in the <a

href="/ssl/ssl_compat.html">Compatibility</a> chapter.</p>

<example><title>Example</title>

CustomLog logs/ssl_request_log \

"%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"

</example>

</section>

<section id="notes"><title>Request Notes</title>

<p><module>mod_ssl</module> sets "notes" for the request which can be

used in logging with the <code>%{<em>name</em>}n</code> format

string in <module>mod_log_config</module>.</p>

<p>The notes supported are as follows:</p>

<dl>

<dt><code>ssl-access-forbidden</code></dt>

<dd>This note is set to the value <code>1</code> if access was

denied due to an <directive>SSLRequire</directive>

or <directive>SSLRequireSSL</directive> directive.</dd>

<dt><code>ssl-secure-reneg</code></dt>

<dd>If <module>mod_ssl</module> is built against a version of

OpenSSL which supports the secure renegotiation extension, this note

is set to the value <code>1</code> if SSL is in used for the current

connection, and the client also supports the secure renegotiation

extension. If the client does not support the secure renegotiation

extension, the note is set to the value <code>0</code>.

If <module>mod_ssl</module> is not built against a version of

OpenSSL which supports secure renegotiation, or if SSL is not in use

for the current connection, the note is not set.</dd>

</dl>

</section>

<section id="authzproviders"><title>Authorization providers for use with Require</title>

<p><module>mod_ssl</module> provides a few authentication providers for use

with <module>mod_authz_core</module>'s

<directive module="mod_authz_core">Require</directive> directive.</p>

<section id="reqssl"><title>Require ssl</title>

<p>The <code>ssl</code> provider denies access if a connection is not

encrypted with SSL. This is similar to the

<directive>SSLRequireSSL</directive> directive.</p>

<example>

Require ssl

</example>

</section>

<section id="reqverifyclient"><title>Require ssl-verify-client</title>

<p>The <code>ssl</code> provider allows access if the user is

authenticated with a valid client certificate. This is only

useful if <code>SSLVerifyClient optional</code> is in effect.</p>

<p>The following example grants access if the user is authenticated

either with a client certificate or by username and password.</p>

<example>

Require ssl-verify-client<br/>

Require valid-user

</example>

</section>

</section>

<directivesynopsis>

<name>SSLPassPhraseDialog</name>

<description>Type of pass phrase dialog for encrypted private

keys</description>

<syntax>SSLPassPhraseDialog <em>type</em></syntax>

<default>SSLPassPhraseDialog builtin</default>

<contextlist><context>server config</context></contextlist>

<usage>

<p>

When Apache starts up it has to read the various Certificate (see

<directive module="mod_ssl">SSLCertificateFile</directive>) and

Private Key (see <directive

module="mod_ssl">SSLCertificateKeyFile</directive>) files of the

SSL-enabled virtual servers. Because for security reasons the Private

Key files are usually encrypted, mod_ssl needs to query the

administrator for a Pass Phrase in order to decrypt those files. This

query can be done in two ways which can be configured by

<em>type</em>:</p>

<ul>

<li><code>builtin</code>

<p>

This is the default where an interactive terminal dialog occurs at startup

time just before Apache detaches from the terminal. Here the administrator

has to manually enter the Pass Phrase for each encrypted Private Key file.

Because a lot of SSL-enabled virtual hosts can be configured, the

following reuse-scheme is used to minimize the dialog: When a Private Key

file is encrypted, all known Pass Phrases (at the beginning there are

none, of course) are tried. If one of those known Pass Phrases succeeds no

dialog pops up for this particular Private Key file. If none succeeded,

another Pass Phrase is queried on the terminal and remembered for the next

round (where it perhaps can be reused).</p>

<p>

This scheme allows mod_ssl to be maximally flexible (because for N encrypted

Private Key files you <em>can</em> use N different Pass Phrases - but then

you have to enter all of them, of course) while minimizing the terminal

dialog (i.e. when you use a single Pass Phrase for all N Private Key files

this Pass Phrase is queried only once).</p></li>

<li><code>|/path/to/program [args...]</code>

<p>This mode allows an external program to be used which acts as a

pipe to a particular input device; the program is sent the standard

prompt text used for the <code>builtin</code> mode on

<code>stdin</code>, and is expected to write password strings on

<code>stdout</code>. If several passwords are needed (or an

incorrect password is entered), additional prompt text will be

written subsequent to the first password being returned, and more

passwords must then be written back.</p></li>

<li><code>exec:/path/to/program</code>

<p>

Here an external program is configured which is called at startup for each

encrypted Private Key file. It is called with two arguments (the first is

of the form ``<code>servername:portnumber</code>'', the second is either

``<code>RSA</code>'' or ``<code>DSA</code>''), which indicate for which

server and algorithm it has to print the corresponding Pass Phrase to

<code>stdout</code>. The intent is that this external program first runs

security checks to make sure that the system is not compromised by an

attacker, and only when these checks were passed successfully it provides

the Pass Phrase.</p>

<p>

Both these security checks, and the way the Pass Phrase is determined, can

be as complex as you like. Mod_ssl just defines the interface: an

executable program which provides the Pass Phrase on <code>stdout</code>.

Nothing more or less! So, if you're really paranoid about security, here

is your interface. Anything else has to be left as an exercise to the

administrator, because local security requirements are so different.</p>

<p>

The reuse-algorithm above is used here, too. In other words: The external

program is called only once per unique Pass Phrase.</p></li>

</ul>

<example><title>Example</title>

SSLPassPhraseDialog exec:/usr/local/apache/sbin/pp-filter

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLRandomSeed</name>

<description>Pseudo Random Number Generator (PRNG) seeding

source</description>

<syntax>SSLRandomSeed <em>context</em> <em>source</em>

[<em>bytes</em>]</syntax>

<contextlist><context>server config</context></contextlist>

<usage>

<p>

This configures one or more sources for seeding the Pseudo Random Number

Generator (PRNG) in OpenSSL at startup time (<em>context</em> is

<code>startup</code>) and/or just before a new SSL connection is established

(<em>context</em> is <code>connect</code>). This directive can only be used

in the global server context because the PRNG is a global facility.</p>

<p>

The following <em>source</em> variants are available:</p>

<ul>

<li><code>builtin</code>

<p> This is the always available builtin seeding source. It's usage

consumes minimum CPU cycles under runtime and hence can be always used

without drawbacks. The source used for seeding the PRNG contains of the

current time, the current process id and (when applicable) a randomly

chosen 1KB extract of the inter-process scoreboard structure of Apache.

The drawback is that this is not really a strong source and at startup

time (where the scoreboard is still not available) this source just

produces a few bytes of entropy. So you should always, at least for the

startup, use an additional seeding source.</p></li>

<li><code>file:/path/to/source</code>

<p>

This variant uses an external file <code>/path/to/source</code> as the

source for seeding the PRNG. When <em>bytes</em> is specified, only the

first <em>bytes</em> number of bytes of the file form the entropy (and

<em>bytes</em> is given to <code>/path/to/source</code> as the first

argument). When <em>bytes</em> is not specified the whole file forms the

entropy (and <code>0</code> is given to <code>/path/to/source</code> as

the first argument). Use this especially at startup time, for instance

with an available <code>/dev/random</code> and/or

<code>/dev/urandom</code> devices (which usually exist on modern Unix

derivatives like FreeBSD and Linux).</p>

<p>

<em>But be careful</em>: Usually <code>/dev/random</code> provides only as

much entropy data as it actually has, i.e. when you request 512 bytes of

entropy, but the device currently has only 100 bytes available two things

can happen: On some platforms you receive only the 100 bytes while on

other platforms the read blocks until enough bytes are available (which

can take a long time). Here using an existing <code>/dev/urandom</code> is

better, because it never blocks and actually gives the amount of requested

data. The drawback is just that the quality of the received data may not

be the best.</p>

<p>

On some platforms like FreeBSD one can even control how the entropy is

actually generated, i.e. by which system interrupts. More details one can

find under <em>rndcontrol(8)</em> on those platforms. Alternatively, when

your system lacks such a random device, you can use tool

like <a href="http://www.lothar.com/tech/crypto/">EGD</a>

(Entropy Gathering Daemon) and run it's client program with the

<code>exec:/path/to/program/</code> variant (see below) or use

<code>egd:/path/to/egd-socket</code> (see below).</p></li>

<li><code>exec:/path/to/program</code>

<p>

This variant uses an external executable

<code>/path/to/program</code> as the source for seeding the

PRNG. When <em>bytes</em> is specified, only the first

<em>bytes</em> number of bytes of its <code>stdout</code> contents

form the entropy. When <em>bytes</em> is not specified, the

entirety of the data produced on <code>stdout</code> form the

entropy. Use this only at startup time when you need a very strong

seeding with the help of an external program (for instance as in

the example above with the <code>truerand</code> utility you can

find in the mod_ssl distribution which is based on the AT&amp;T

<em>truerand</em> library). Using this in the connection context

slows down the server too dramatically, of course. So usually you

should avoid using external programs in that context.</p></li>

<li><code>egd:/path/to/egd-socket</code> (Unix only)

<p>

This variant uses the Unix domain socket of the

external Entropy Gathering Daemon (EGD) (see <a

href="http://www.lothar.com/tech/crypto/">http://www.lothar.com/tech

/crypto/</a>) to seed the PRNG. Use this if no random device exists

on your platform.</p></li>

</ul>

<example><title>Example</title>

SSLRandomSeed startup builtin<br />

SSLRandomSeed startup file:/dev/random<br />

SSLRandomSeed startup file:/dev/urandom 1024<br />

SSLRandomSeed startup exec:/usr/local/bin/truerand 16<br />

SSLRandomSeed connect builtin<br />

SSLRandomSeed connect file:/dev/random<br />

SSLRandomSeed connect file:/dev/urandom 1024<br />

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLSessionCache</name>

<description>Type of the global/inter-process SSL Session

Cache</description>

<syntax>SSLSessionCache <em>type</em></syntax>

<default>SSLSessionCache none</default>

<contextlist><context>server config</context></contextlist>

<usage>

<p>

This configures the storage type of the global/inter-process SSL Session

Cache. This cache is an optional facility which speeds up parallel request

processing. For requests to the same server process (via HTTP keep-alive),

OpenSSL already caches the SSL session information locally. But because modern

clients request inlined images and other data via parallel requests (usually

up to four parallel requests are common) those requests are served by

<em>different</em> pre-forked server processes. Here an inter-process cache

helps to avoid unnecessary session handshakes.</p>

<p>

The following five storage <em>type</em>s are currently supported:</p>

<ul>

<li><code>none</code>

<p>This disables the global/inter-process Session Cache. This

will incur a noticeable speed penalty and may cause problems if

using certain browsers, particularly if client certificates are

enabled. This setting is not recommended.</p></li>

<li><code>nonenotnull</code>

<p>This disables any global/inter-process Session Cache. However

it does force OpenSSL to send a non-null session ID to

accommodate buggy clients that require one.</p></li>

<li><code>dbm:/path/to/datafile</code>

<p>This makes use of a DBM hashfile on the local disk to

synchronize the local OpenSSL memory caches of the server

processes. This session cache may suffer reliability issues under

high load. To use this, ensure that

<module>mod_socache_dbm</module> is loaded.</p></li>

<li><code>shmcb:/path/to/datafile</code>[<code>(</code><em>size</em><code>)</code>]

<p>This makes use of a high-performance cyclic buffer

(approx. <em>size</em> bytes in size) inside a shared memory

segment in RAM (established via <code>/path/to/datafile</code>) to

synchronize the local OpenSSL memory caches of the server

processes. This is the recommended session cache. To use this,

ensure that <module>mod_socache_shmcb</module> is loaded.</p></li>

<li><code>dc:UNIX:/path/to/socket</code>

<p>This makes use of the <a

href="http://www.distcache.org/">distcache</a> distributed session

caching libraries. The argument should specify the location of

the server or proxy to be used using the distcache address syntax;

for example, <code>UNIX:/path/to/socket</code> specifies a UNIX

domain socket (typically a local dc_client proxy);

<code>IP:server.example.com:9001</code> specifies an IP

address. To use this, ensure that

<module>mod_socache_dc</module> is loaded.</p></li>

</ul>

<example><title>Examples</title>

SSLSessionCache dbm:/usr/local/apache/logs/ssl_gcache_data<br />

SSLSessionCache shmcb:/usr/local/apache/logs/ssl_gcache_data(512000)

</example>

<p>The <code>ssl-cache</code> mutex is used to serialize access to

the session cache to prevent corruption. This mutex can be configured

using the <directive module="core">Mutex</directive> directive.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLSessionCacheTimeout</name>

<description>Number of seconds before an SSL session expires

in the Session Cache</description>

<syntax>SSLSessionCacheTimeout <em>seconds</em></syntax>

<default>SSLSessionCacheTimeout 300</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the timeout in seconds for the information stored in the

global/inter-process SSL Session Cache and the OpenSSL internal memory cache.

It can be set as low as 15 for testing, but should be set to higher

values like 300 in real life.</p>

<example><title>Example</title>

SSLSessionCacheTimeout 600

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLEngine</name>

<description>SSL Engine Operation Switch</description>

<syntax>SSLEngine on|off|optional</syntax>

<default>SSLEngine off</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive toggles the usage of the SSL/TLS Protocol Engine. This

is should be used inside a <directive module="core"

type="section">VirtualHost</directive> section to enable SSL/TLS for a

that virtual host. By default the SSL/TLS Protocol Engine is

disabled for both the main server and all configured virtual hosts.</p>

<example><title>Example</title>

&lt;VirtualHost _default_:443&gt;<br />

SSLEngine on<br />

...<br />

&lt;/VirtualHost&gt;

</example>

<p>In Apache 2.1 and later, <directive>SSLEngine</directive> can be set to

<code>optional</code>. This enables support for

<a href="http://www.ietf.org/rfc/rfc2817.txt">RFC 2817</a>, Upgrading to TLS

Within HTTP/1.1. At this time no web browsers support RFC 2817.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLFIPS</name>

<description>SSL FIPS mode Switch</description>

<syntax>SSLFIPS on|off</syntax>

<default>SSLFIPS off</default>

<contextlist><context>server config</context></contextlist>

<usage>

<p>

This directive toggles the usage of the SSL library FIPS_mode flag.

It must be set in the global server context and cannot be configured

with conflicting settings (SSLFIPS on followed by SSLFIPS off or

similar). The mode applies to all SSL library operations.

</p>

<p>

If httpd was compiled against an SSL library which did not support

the FIPS_mode flag, <code>SSLFIPS on</code> will fail. Refer to the

FIPS 140-2 Security Policy document of the SSL provider library for

specific requirements to use mod_ssl in a FIPS 140-2 approved mode

of operation; note that mod_ssl itself is not validated, but may be

described as using FIPS 140-2 validated cryptographic module, when

all components are assembled and operated under the guidelines imposed

by the applicable Security Policy.

</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProtocol</name>

<description>Configure usable SSL/TLS protocol versions</description>

<syntax>SSLProtocol [+|-]<em>protocol</em> ...</syntax>

<default>SSLProtocol all</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive can be used to control which versions of the SSL/TLS protocol

will be accepted in new connections.</p>

<p>

The available (case-insensitive) <em>protocol</em>s are:</p>

<ul>

<li><code>SSLv3</code>

<p>

This is the Secure Sockets Layer (SSL) protocol, version 3.0, from

the Netscape Corporation.

It is the successor to SSLv2 and the predecessor to TLSv1. It's supported by

almost all popular browsers.</p></li>

<li><code>TLSv1</code>

<p>

This is the Transport Layer Security (TLS) protocol, version 1.0.

It is the successor to SSLv3 and is defined in

<a href="http://www.ietf.org/rfc/rfc2246.txt">RFC 2246</a>.</p></li>

<li><code>TLSv1.1</code> (when using OpenSSL 1.0.1 and later)

<p>

A revision of the TLS 1.0 protocol, as defined in

<a href="http://www.ietf.org/rfc/rfc4346.txt">RFC 4346</a>.</p></li>

<li><code>TLSv1.2</code> (when using OpenSSL 1.0.1 and later)

<p>

A revision of the TLS 1.1 protocol, as defined in

<a href="http://www.ietf.org/rfc/rfc5246.txt">RFC 5246</a>.</p></li>

<li><code>all</code>

<p>

This is a shortcut for ``<code>+SSLv3 +TLSv1</code>'' or

- when using OpenSSL 1.0.1 and later -

``<code>+SSLv3 +TLSv1 +TLSv1.1 +TLSv1.2</code>, respectively.</p></li>

</ul>

<example><title>Example</title>

SSLProtocol TLSv1

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCipherSuite</name>

<description>Cipher Suite available for negotiation in SSL

handshake</description>

<syntax>SSLCipherSuite <em>cipher-spec</em></syntax>

<default>SSLCipherSuite DEFAULT (depends on OpenSSL version)</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context></contextlist>

<override>AuthConfig</override>

<usage>

<p>

This complex directive uses a colon-separated <em>cipher-spec</em> string

consisting of OpenSSL cipher specifications to configure the Cipher Suite the

client is permitted to negotiate in the SSL handshake phase. Notice that this

directive can be used both in per-server and per-directory context. In

per-server context it applies to the standard SSL handshake when a connection

is established. In per-directory context it forces a SSL renegotiation with the

reconfigured Cipher Suite after the HTTP request was read but before the HTTP

response is sent.</p>

<p>

An SSL cipher specification in <em>cipher-spec</em> is composed of 4 major

attributes plus a few extra minor ones:</p>

<ul>

<li><em>Key Exchange Algorithm</em>:<br />

RSA or Diffie-Hellman variants.

</li>

<li><em>Authentication Algorithm</em>:<br />

RSA, Diffie-Hellman, DSS or none.

</li>

<li><em>Cipher/Encryption Algorithm</em>:<br />

DES, Triple-DES, RC4, RC2, IDEA or none.

</li>

<li><em>MAC Digest Algorithm</em>:<br />

MD5, SHA or SHA1.

</li>

</ul>

<p>An SSL cipher can also be an export cipher and is either an SSLv2 or SSLv3/TLSv1

cipher (here TLSv1 is equivalent to SSLv3). To specify which ciphers to use,

one can either specify all the Ciphers, one at a time, or use aliases to

specify the preference and order for the ciphers (see <a href="#table1">Table

1</a>).</p>

<table border="1">

<columnspec><column width=".5"/><column width=".5"/></columnspec>

<tr><th><a name="table1">Tag</a></th> <th>Description</th></tr>

<tr><td colspan="2"><em>Key Exchange Algorithm:</em></td></tr>

<tr><td><code>kRSA</code></td> <td>RSA key exchange</td></tr>

<tr><td><code>kDHr</code></td> <td>Diffie-Hellman key exchange with RSA key</td></tr>

<tr><td><code>kDHd</code></td> <td>Diffie-Hellman key exchange with DSA key</td></tr>

<tr><td><code>kEDH</code></td> <td>Ephemeral (temp.key) Diffie-Hellman key exchange (no cert)</td> </tr>

<tr><td colspan="2"><em>Authentication Algorithm:</em></td></tr>

<tr><td><code>aNULL</code></td> <td>No authentication</td></tr>

<tr><td><code>aRSA</code></td> <td>RSA authentication</td></tr>

<tr><td><code>aDSS</code></td> <td>DSS authentication</td> </tr>

<tr><td><code>aDH</code></td> <td>Diffie-Hellman authentication</td></tr>

<tr><td colspan="2"><em>Cipher Encoding Algorithm:</em></td></tr>

<tr><td><code>eNULL</code></td> <td>No encoding</td> </tr>

<tr><td><code>DES</code></td> <td>DES encoding</td> </tr>

<tr><td><code>3DES</code></td> <td>Triple-DES encoding</td> </tr>

<tr><td><code>RC4</code></td> <td>RC4 encoding</td> </tr>

<tr><td><code>RC2</code></td> <td>RC2 encoding</td> </tr>

<tr><td><code>IDEA</code></td> <td>IDEA encoding</td> </tr>

<tr><td colspan="2"><em>MAC Digest Algorithm</em>:</td></tr>

<tr><td><code>MD5</code></td> <td>MD5 hash function</td></tr>

<tr><td><code>SHA1</code></td> <td>SHA1 hash function</td></tr>

<tr><td><code>SHA</code></td> <td>SHA hash function</td> </tr>

<tr><td colspan="2"><em>Aliases:</em></td></tr>

<tr><td><code>SSLv2</code></td> <td>all SSL version 2.0 ciphers</td></tr>

<tr><td><code>SSLv3</code></td> <td>all SSL version 3.0 ciphers</td> </tr>

<tr><td><code>TLSv1</code></td> <td>all TLS version 1.0 ciphers</td> </tr>

<tr><td><code>EXP</code></td> <td>all export ciphers</td> </tr>

<tr><td><code>EXPORT40</code></td> <td>all 40-bit export ciphers only</td> </tr>

<tr><td><code>EXPORT56</code></td> <td>all 56-bit export ciphers only</td> </tr>

<tr><td><code>LOW</code></td> <td>all low strength ciphers (no export, single DES)</td></tr>

<tr><td><code>MEDIUM</code></td> <td>all ciphers with 128 bit encryption</td> </tr>

<tr><td><code>HIGH</code></td> <td>all ciphers using Triple-DES</td> </tr>

<tr><td><code>RSA</code></td> <td>all ciphers using RSA key exchange</td> </tr>

<tr><td><code>DH</code></td> <td>all ciphers using Diffie-Hellman key exchange</td> </tr>

<tr><td><code>EDH</code></td> <td>all ciphers using Ephemeral Diffie-Hellman key exchange</td> </tr>

<tr><td><code>ADH</code></td> <td>all ciphers using Anonymous Diffie-Hellman key exchange</td> </tr>

<tr><td><code>DSS</code></td> <td>all ciphers using DSS authentication</td> </tr>

<tr><td><code>NULL</code></td> <td>all ciphers using no encryption</td> </tr>

</table>

<p>

Now where this becomes interesting is that these can be put together

to specify the order and ciphers you wish to use. To speed this up

there are also aliases (<code>SSLv2, SSLv3, TLSv1, EXP, LOW, MEDIUM,

HIGH</code>) for certain groups of ciphers. These tags can be joined

together with prefixes to form the <em>cipher-spec</em>. Available

prefixes are:</p>

<ul>

<li>none: add cipher to list</li>

<li><code>+</code>: add ciphers to list and pull them to current location in list</li>

<li><code>-</code>: remove cipher from list (can be added later again)</li>

<li><code>!</code>: kill cipher from list completely (can <strong>not</strong> be added later again)</li>

</ul>

<p>A simpler way to look at all of this is to use the ``<code>openssl ciphers

-v</code>'' command which provides a nice way to successively create the

correct <em>cipher-spec</em> string. The default <em>cipher-spec</em> string

depends on the version of the OpenSSL libraries used. Let's suppose it is

``<code>ALL:!aNULL:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP</code>'' which

means the following: first, remove from consideration any ciphers that do not

authenticate, i.e. for SSL the Anonymous Diffie-Hellman ciphers. Next,

use ciphers using RC4 and RSA. Next include the high, medium and then the low

security ciphers. Finally <em>pull</em> all SSLv2 and export ciphers to the

end of the list.</p>

<example>

<pre>

$ openssl ciphers -v 'ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP'

NULL-SHA SSLv3 Kx=RSA Au=RSA Enc=None Mac=SHA1

NULL-MD5 SSLv3 Kx=RSA Au=RSA Enc=None Mac=MD5

EDH-RSA-DES-CBC3-SHA SSLv3 Kx=DH Au=RSA Enc=3DES(168) Mac=SHA1

... ... ... ... ...

EXP-RC4-MD5 SSLv3 Kx=RSA(512) Au=RSA Enc=RC4(40) Mac=MD5 export

EXP-RC2-CBC-MD5 SSLv2 Kx=RSA(512) Au=RSA Enc=RC2(40) Mac=MD5 export

EXP-RC4-MD5 SSLv2 Kx=RSA(512) Au=RSA Enc=RC4(40) Mac=MD5 export

</pre>

</example>

<p>The complete list of particular RSA &amp; DH ciphers for SSL is given in <a

href="#table2">Table 2</a>.</p>

<example><title>Example</title>

SSLCipherSuite RSA:!EXP:!NULL:+HIGH:+MEDIUM:-LOW

</example>

<table border="1">

<columnspec><column width=".3"/><column width=".1"/><column width=".13"/>

<column width=".1"/><column width=".13"/><column width=".1"/>

<column width=".13"/></columnspec>

<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>

<tr><td colspan="7"><em>RSA Ciphers:</em></td></tr>

<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>

<tr><td><code>DES-CBC3-MD5</code></td> <td>SSLv2</td> <td>RSA</td> <td>RSA</td> <td>3DES(168)</td> <td>MD5</td> <td></td> </tr>

<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>

<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>

<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>

<tr><td><code>IDEA-CBC-MD5</code></td> <td>SSLv2</td> <td>RSA</td> <td>RSA</td> <td>IDEA(128)</td> <td>MD5</td> <td></td> </tr>

<tr><td><code>RC2-CBC-MD5</code></td> <td>SSLv2</td> <td>RSA</td> <td>RSA</td> <td>RC2(128)</td> <td>MD5</td> <td></td> </tr>

<tr><td><code>RC4-MD5</code></td> <td>SSLv2</td> <td>RSA</td> <td>RSA</td> <td>RC4(128)</td> <td>MD5</td> <td></td> </tr>

<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>

<tr><td><code>RC4-64-MD5</code></td> <td>SSLv2</td> <td>RSA</td> <td>RSA</td> <td>RC4(64)</td> <td>MD5</td> <td></td> </tr>

<tr><td><code>DES-CBC-MD5</code></td> <td>SSLv2</td> <td>RSA</td> <td>RSA</td> <td>DES(56)</td> <td>MD5</td> <td></td> </tr>

<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>

<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>

<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>

<tr><td><code>EXP-RC2-CBC-MD5</code></td> <td>SSLv2</td> <td>RSA(512)</td> <td>RSA</td> <td>RC2(40)</td> <td>MD5</td> <td> export</td> </tr>

<tr><td><code>EXP-RC4-MD5</code></td> <td>SSLv2</td> <td>RSA(512)</td> <td>RSA</td> <td>RC4(40)</td> <td>MD5</td> <td> export</td> </tr>

<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>

<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>

<tr><td colspan="7"><em>Diffie-Hellman Ciphers:</em></td></tr>

<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>

<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>

<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>

<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>

<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>

<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>

<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>

<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>

<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>

<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>

<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>

</table>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCertificateFile</name>

<description>Server PEM-encoded X.509 Certificate file</description>

<syntax>SSLCertificateFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive points to the PEM-encoded Certificate file for the server and

optionally also to the corresponding RSA or DSA Private Key file for it

(contained in the same file). If the contained Private Key is encrypted the

Pass Phrase dialog is forced at startup time. This directive can be used up to

two times (referencing different filenames) when both a RSA and a DSA based

server certificate is used in parallel.</p>

<example><title>Example</title>

SSLCertificateFile /usr/local/apache2/conf/ssl.crt/server.crt

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCertificateKeyFile</name>

<description>Server PEM-encoded Private Key file</description>

<syntax>SSLCertificateKeyFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive points to the PEM-encoded Private Key file for the

server. If the Private Key is not combined with the Certificate in the

<directive>SSLCertificateFile</directive>, use this additional directive to

point to the file with the stand-alone Private Key. When

<directive>SSLCertificateFile</directive> is used and the file

contains both the Certificate and the Private Key this directive need

not be used. But we strongly discourage this practice. Instead we

recommend you to separate the Certificate and the Private Key. If the

contained Private Key is encrypted, the Pass Phrase dialog is forced

at startup time. This directive can be used up to two times

(referencing different filenames) when both a RSA and a DSA based

private key is used in parallel.</p>

<example><title>Example</title>

SSLCertificateKeyFile /usr/local/apache2/conf/ssl.key/server.key

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCertificateChainFile</name>

<description>File of PEM-encoded Server CA Certificates</description>

<syntax>SSLCertificateChainFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the optional <em>all-in-one</em> file where you can

assemble the certificates of Certification Authorities (CA) which form the

certificate chain of the server certificate. This starts with the issuing CA

certificate of the server certificate and can range up to the root CA

certificate. Such a file is simply the concatenation of the various

PEM-encoded CA Certificate files, usually in certificate chain order.</p>

<p>

This should be used alternatively and/or additionally to <directive

module="mod_ssl">SSLCACertificatePath</directive> for explicitly

constructing the server certificate chain which is sent to the browser

in addition to the server certificate. It is especially useful to

avoid conflicts with CA certificates when using client

authentication. Because although placing a CA certificate of the

server certificate chain into <directive

module="mod_ssl">SSLCACertificatePath</directive> has the same effect

for the certificate chain construction, it has the side-effect that

client certificates issued by this same CA certificate are also

accepted on client authentication.</p>

<p>

But be careful: Providing the certificate chain works only if you are using a

<em>single</em> RSA <em>or</em> DSA based server certificate. If you are

using a coupled RSA+DSA certificate pair, this will work only if actually both

certificates use the <em>same</em> certificate chain. Else the browsers will be

confused in this situation.</p>

<example><title>Example</title>

SSLCertificateChainFile /usr/local/apache2/conf/ssl.crt/ca.crt

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCACertificatePath</name>

<description>Directory of PEM-encoded CA Certificates for

Client Auth</description>

<syntax>SSLCACertificatePath <em>directory-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the directory where you keep the Certificates of

Certification Authorities (CAs) whose clients you deal with. These are used to

verify the client certificate on Client Authentication.</p>

<p>

The files in this directory have to be PEM-encoded and are accessed through

hash filenames. So usually you can't just place the Certificate files

there: you also have to create symbolic links named

<em>hash-value</em><code>.N</code>. And you should always make sure this directory

contains the appropriate symbolic links. Use the <code>Makefile</code> which

comes with mod_ssl to accomplish this task.</p>

<example><title>Example</title>

SSLCACertificatePath /usr/local/apache2/conf/ssl.crt/

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCACertificateFile</name>

<description>File of concatenated PEM-encoded CA Certificates

for Client Auth</description>

<syntax>SSLCACertificateFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the <em>all-in-one</em> file where you can assemble the

Certificates of Certification Authorities (CA) whose <em>clients</em> you deal

with. These are used for Client Authentication. Such a file is simply the

concatenation of the various PEM-encoded Certificate files, in order of

preference. This can be used alternatively and/or additionally to

<directive module="mod_ssl">SSLCACertificatePath</directive>.</p>

<example><title>Example</title>

SSLCACertificateFile /usr/local/apache2/conf/ssl.crt/ca-bundle-client.crt

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCADNRequestFile</name>

<description>File of concatenated PEM-encoded CA Certificates

for defining acceptable CA names</description>

<syntax>SSLCADNRequestFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>When a client certificate is requested by mod_ssl, a list of

<em>acceptable Certificate Authority names</em> is sent to the client

in the SSL handshake. These CA names can be used by the client to

select an appropriate client certificate out of those it has

available.</p>

<p>If neither of the directives <directive

module="mod_ssl">SSLCADNRequestPath</directive> or <directive

module="mod_ssl">SSLCADNRequestFile</directive> are given, then the

set of acceptable CA names sent to the client is the names of all the

CA certificates given by the <directive

module="mod_ssl">SSLCACertificateFile</directive> and <directive

module="mod_ssl">SSLCACertificatePath</directive> directives; in other

words, the names of the CAs which will actually be used to verify the

client certificate.</p>

<p>In some circumstances, it is useful to be able to send a set of

acceptable CA names which differs from the actual CAs used to verify

the client certificate - for example, if the client certificates are

signed by intermediate CAs. In such cases, <directive

module="mod_ssl">SSLCADNRequestPath</directive> and/or <directive

module="mod_ssl">SSLCADNRequestFile</directive> can be used; the

acceptable CA names are then taken from the complete set of

certificates in the directory and/or file specified by this pair of

directives.</p>

<p><directive module="mod_ssl">SSLCADNRequestFile</directive> must

specify an <em>all-in-one</em> file containing a concatenation of

PEM-encoded CA certificates.</p>

<example><title>Example</title>

SSLCADNRequestFile /usr/local/apache2/conf/ca-names.crt

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCADNRequestPath</name>

<description>Directory of PEM-encoded CA Certificates for

defining acceptable CA names</description>

<syntax>SSLCADNRequestPath <em>directory-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>This optional directive can be used to specify the set of

<em>acceptable CA names</em> which will be sent to the client when a

client certificate is requested. See the <directive

module="mod_ssl">SSLCADNRequestFile</directive> directive for more

details.</p>

<p>The files in this directory have to be PEM-encoded and are accessed

through hash filenames. So usually you can't just place the

Certificate files there: you also have to create symbolic links named

<em>hash-value</em><code>.N</code>. And you should always make sure

this directory contains the appropriate symbolic links. Use the

<code>Makefile</code> which comes with mod_ssl to accomplish this

task.</p>

<example><title>Example</title>

SSLCADNRequestPath /usr/local/apache2/conf/ca-names.crt/

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCARevocationPath</name>

<description>Directory of PEM-encoded CA CRLs for

Client Auth</description>

<syntax>SSLCARevocationPath <em>directory-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the directory where you keep the Certificate Revocation

Lists (CRL) of Certification Authorities (CAs) whose clients you deal with.

These are used to revoke the client certificate on Client Authentication.</p>

<p>

The files in this directory have to be PEM-encoded and are accessed through

hash filenames. So usually you have not only to place the CRL files there.

Additionally you have to create symbolic links named

<em>hash-value</em><code>.rN</code>. And you should always make sure this directory

contains the appropriate symbolic links. Use the <code>Makefile</code> which

comes with <module>mod_ssl</module> to accomplish this task.</p>

<example><title>Example</title>

SSLCARevocationPath /usr/local/apache2/conf/ssl.crl/

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCARevocationFile</name>

<description>File of concatenated PEM-encoded CA CRLs for

Client Auth</description>

<syntax>SSLCARevocationFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the <em>all-in-one</em> file where you can

assemble the Certificate Revocation Lists (CRL) of Certification

Authorities (CA) whose <em>clients</em> you deal with. These are used

for Client Authentication. Such a file is simply the concatenation of

the various PEM-encoded CRL files, in order of preference. This can be

used alternatively and/or additionally to <directive

module="mod_ssl">SSLCARevocationPath</directive>.</p>

<example><title>Example</title>

SSLCARevocationFile /usr/local/apache2/conf/ssl.crl/ca-bundle-client.crl

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCARevocationCheck</name>

<description>Enable CRL-based revocation checking</description>

<syntax>SSLCARevocationCheck chain|leaf|none</syntax>

<default>SSLCARevocationCheck none</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

Enables certificate revocation list (CRL) checking. At least one of

<directive module="mod_ssl">SSLCARevocationFile</directive>

or <directive module="mod_ssl">SSLCARevocationPath</directive> must be

configured. When set to <code>chain</code> (recommended setting),

CRL checks are applied to all certificates in the chain, while setting it to

<code>leaf</code> limits the checks to the end-entity cert.

</p>

<note>

<title>When set to <code>chain</code> or <code>leaf</code>,

CRLs <em>must</em> be available for successful validation</title>

<p>

Prior to version 2.3.15, CRL checking in mod_ssl also succeeded when

no CRL(s) were found in any of the locations configured with

<directive module="mod_ssl">SSLCARevocationFile</directive>

or <directive module="mod_ssl">SSLCARevocationPath</directive>.

With the introduction of this directive, the behavior has been changed:

when checking is enabled, CRLs <em>must</em> be present for the validation

to succeed - otherwise it will fail with an

<code>"unable to get certificate CRL"</code> error.

</p>

</note>

<example><title>Example</title>

SSLCARevocationCheck chain

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLVerifyClient</name>

<description>Type of Client Certificate verification</description>

<syntax>SSLVerifyClient <em>level</em></syntax>

<default>SSLVerifyClient none</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context></contextlist>

<override>AuthConfig</override>

<usage>

<p>

This directive sets the Certificate verification level for the Client

Authentication. Notice that this directive can be used both in per-server and

per-directory context. In per-server context it applies to the client

authentication process used in the standard SSL handshake when a connection is

established. In per-directory context it forces a SSL renegotiation with the

reconfigured client verification level after the HTTP request was read but

before the HTTP response is sent.</p>

<p>

The following levels are available for <em>level</em>:</p>

<ul>

<li><strong>none</strong>:

no client Certificate is required at all</li>

<li><strong>optional</strong>:

the client <em>may</em> present a valid Certificate</li>

<li><strong>require</strong>:

the client <em>has to</em> present a valid Certificate</li>

<li><strong>optional_no_ca</strong>:

the client may present a valid Certificate<br />

but it need not to be (successfully) verifiable.</li>

</ul>

<p>In practice only levels <strong>none</strong> and

<strong>require</strong> are really interesting, because level

<strong>optional</strong> doesn't work with all browsers and level

<strong>optional_no_ca</strong> is actually against the idea of

authentication (but can be used to establish SSL test pages, etc.)</p>

<example><title>Example</title>

SSLVerifyClient require

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLVerifyDepth</name>

<description>Maximum depth of CA Certificates in Client

Certificate verification</description>

<syntax>SSLVerifyDepth <em>number</em></syntax>

<default>SSLVerifyDepth 1</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context></contextlist>

<override>AuthConfig</override>

<usage>

<p>

This directive sets how deeply mod_ssl should verify before deciding that the

clients don't have a valid certificate. Notice that this directive can be

used both in per-server and per-directory context. In per-server context it

applies to the client authentication process used in the standard SSL

handshake when a connection is established. In per-directory context it forces

a SSL renegotiation with the reconfigured client verification depth after the

HTTP request was read but before the HTTP response is sent.</p>

<p>

The depth actually is the maximum number of intermediate certificate issuers,

i.e. the number of CA certificates which are max allowed to be followed while

verifying the client certificate. A depth of 0 means that self-signed client

certificates are accepted only, the default depth of 1 means the client

certificate can be self-signed or has to be signed by a CA which is directly

known to the server (i.e. the CA's certificate is under

<directive module="mod_ssl">SSLCACertificatePath</directive>), etc.</p>

<example><title>Example</title>

SSLVerifyDepth 10

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLOptions</name>

<description>Configure various SSL engine run-time options</description>

<syntax>SSLOptions [+|-]<em>option</em> ...</syntax>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context></contextlist>

<override>Options</override>

<usage>

<p>

This directive can be used to control various run-time options on a

per-directory basis. Normally, if multiple <code>SSLOptions</code>

could apply to a directory, then the most specific one is taken

completely; the options are not merged. However if <em>all</em> the

options on the <code>SSLOptions</code> directive are preceded by a

plus (<code>+</code>) or minus (<code>-</code>) symbol, the options

are merged. Any options preceded by a <code>+</code> are added to the

options currently in force, and any options preceded by a

<code>-</code> are removed from the options currently in force.</p>

<p>

The available <em>option</em>s are:</p>

<ul>

<li><code>StdEnvVars</code>

<p>

When this option is enabled, the standard set of SSL related CGI/SSI

environment variables are created. This per default is disabled for

performance reasons, because the information extraction step is a

rather expensive operation. So one usually enables this option for

CGI and SSI requests only.</p>

</li>

<li><code>ExportCertData</code>

<p>

When this option is enabled, additional CGI/SSI environment variables are

created: <code>SSL_SERVER_CERT</code>, <code>SSL_CLIENT_CERT</code> and

<code>SSL_CLIENT_CERT_CHAIN_</code><em>n</em> (with <em>n</em> = 0,1,2,..).

These contain the PEM-encoded X.509 Certificates of server and client for

the current HTTPS connection and can be used by CGI scripts for deeper

Certificate checking. Additionally all other certificates of the client

certificate chain are provided, too. This bloats up the environment a

little bit which is why you have to use this option to enable it on

demand.</p>

</li>

<li><code>FakeBasicAuth</code>

<p>

When this option is enabled, the Subject Distinguished Name (DN) of the

Client X509 Certificate is translated into a HTTP Basic Authorization

username. This means that the standard Apache authentication methods can

be used for access control. The user name is just the Subject of the

Client's X509 Certificate (can be determined by running OpenSSL's

<code>openssl x509</code> command: <code>openssl x509 -noout -subject -in

</code><em>certificate</em><code>.crt</code>). Note that no password is

obtained from the user. Every entry in the user file needs this password:

``<code>xxj31ZMTZzkVA</code>'', which is the DES-encrypted version of the

word `<code>password</code>''. Those who live under MD5-based encryption

(for instance under FreeBSD or BSD/OS, etc.) should use the following MD5

hash of the same word: ``<code>$1$OXLyS...$Owx8s2/m9/gfkcRVXzgoE/</code>''.</p>

</li>

<li><code>StrictRequire</code>

<p>

This <em>forces</em> forbidden access when <code>SSLRequireSSL</code> or

<code>SSLRequire</code> successfully decided that access should be

forbidden. Usually the default is that in the case where a ``<code>Satisfy

any</code>'' directive is used, and other access restrictions are passed,

denial of access due to <code>SSLRequireSSL</code> or

<code>SSLRequire</code> is overridden (because that's how the Apache

<code>Satisfy</code> mechanism should work.) But for strict access restriction

you can use <code>SSLRequireSSL</code> and/or <code>SSLRequire</code> in

combination with an ``<code>SSLOptions +StrictRequire</code>''. Then an

additional ``<code>Satisfy Any</code>'' has no chance once mod_ssl has

decided to deny access.</p>

</li>

<li><code>OptRenegotiate</code>

<p>

This enables optimized SSL connection renegotiation handling when SSL

directives are used in per-directory context. By default a strict

scheme is enabled where <em>every</em> per-directory reconfiguration of

SSL parameters causes a <em>full</em> SSL renegotiation handshake. When this

option is used mod_ssl tries to avoid unnecessary handshakes by doing more

granular (but still safe) parameter checks. Nevertheless these granular

checks sometimes maybe not what the user expects, so enable this on a

per-directory basis only, please.</p>

</li>

<li><code>LegacyDNStringFormat</code>

<p>

This option influences how values of the

<code>SSL_{CLIENT,SERVER}_{I,S}_DN</code> variables are formatted. Since

version 2.3.11, Apache HTTPD uses a RFC 2253 compatible format by

default. This uses commas as delimiters between the attributes, allows the

use of non-ASCII characters (which are converted to UTF8), escapes

various special characters with backslashes, and sorts the attributes

with the "C" attribute last.</p>

<p>If <code>LegacyDNStringFormat</code> is set, the old format will be

used which sorts the "C" attribute first, uses slashes as separators, and

does not handle non-ASCII and special characters in any consistent way.

</p>

</li>

</ul>

<example><title>Example</title>

SSLOptions +FakeBasicAuth -StrictRequire<br />

&lt;Files ~ "\.(cgi|shtml)$"&gt;<br />

SSLOptions +StdEnvVars -ExportCertData<br />

&lt;Files&gt;

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLRequireSSL</name>

<description>Deny access when SSL is not used for the

HTTP request</description>

<syntax>SSLRequireSSL</syntax>

<contextlist><context>directory</context>

<context>.htaccess</context></contextlist>

<override>AuthConfig</override>

<usage>

<p><!-- XXX: I think the syntax is wrong -->

This directive forbids access unless HTTP over SSL (i.e. HTTPS) is enabled for

the current connection. This is very handy inside the SSL-enabled virtual

host or directories for defending against configuration errors that expose

stuff that should be protected. When this directive is present all requests

are denied which are not using SSL.</p>

<example><title>Example</title>

SSLRequireSSL

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLRequire</name>

<description>Allow access only when an arbitrarily complex

boolean expression is true</description>

<syntax>SSLRequire <em>expression</em></syntax>

<contextlist><context>directory</context>

<context>.htaccess</context></contextlist>

<override>AuthConfig</override>

<usage>

<p>

This directive specifies a general access requirement which has to be

fulfilled in order to allow access. It is a very powerful directive because the

requirement specification is an arbitrarily complex boolean expression

containing any number of access checks.</p>

<p>

The <em>expression</em> must match the following syntax (given as a BNF

grammar notation):</p>

<blockquote>

<pre>

expr ::= "<strong>true</strong>" | "<strong>false</strong>"

| "<strong>!</strong>" expr

| expr "<strong>&amp;&amp;</strong>" expr

| expr "<strong>||</strong>" expr

| "<strong>(</strong>" expr "<strong>)</strong>"

| comp

comp ::= word "<strong>==</strong>" word | word "<strong>eq</strong>" word

| word "<strong>!=</strong>" word | word "<strong>ne</strong>" word

| word "<strong>&lt;</strong>" word | word "<strong>lt</strong>" word

| word "<strong>&lt;=</strong>" word | word "<strong>le</strong>" word

| word "<strong>&gt;</strong>" word | word "<strong>gt</strong>" word

| word "<strong>&gt;=</strong>" word | word "<strong>ge</strong>" word

| word "<strong>in</strong>" "<strong>{</strong>" wordlist "<strong>}</strong>"

| word "<strong>in</strong>" "<strong>PeerExtList(</strong>" word "<strong>)</strong>"

| word "<strong>=~</strong>" regex

| word "<strong>!~</strong>" regex

wordlist ::= word

| wordlist "<strong>,</strong>" word

word ::= digit

| cstring

| variable

| function

digit ::= [0-9]+

cstring ::= "..."

variable ::= "<strong>%{</strong>" varname "<strong>}</strong>"

function ::= funcname "<strong>(</strong>" funcargs "<strong>)</strong>"

</pre>

</blockquote>

<p>For <code>varname</code> any of the variables described in <a

href="#envvars">Environment Variables</a> can be used. For

<code>funcname</code> the available functions are listed in

the <a href="/expr.html#functions">ap_expr documentation</a>.</p>

<p>Notice that <em>expression</em> is first parsed into an internal machine

representation and then evaluated in a second step. Actually, in Global and

Per-Server Class context <em>expression</em> is parsed at startup time and

at runtime only the machine representation is executed. For Per-Directory

context this is different: here <em>expression</em> has to be parsed and

immediately executed for every request.</p>

<example><title>Example</title>

<pre>SSLRequire ( %{SSL_CIPHER} !~ m/^(EXP|NULL)-/ \

and %{SSL_CLIENT_S_DN_O} eq "Snake Oil, Ltd." \

and %{SSL_CLIENT_S_DN_OU} in {"Staff", "CA", "Dev"} \

and %{TIME_WDAY} &gt;= 1 and %{TIME_WDAY} &lt;= 5 \

and %{TIME_HOUR} &gt;= 8 and %{TIME_HOUR} &lt;= 20 ) \

or %{REMOTE_ADDR} =~ m/^192\.76\.162\.[0-9]+$/</pre>

</example>

<p>The <code>PeerExtList(<em>object-ID</em>)</code> function expects

to find zero or more instances of the X.509 certificate extension

identified by the given <em>object ID</em> (OID) in the client certificate.

The expression evaluates to true if the left-hand side string matches

exactly against the value of an extension identified with this OID.

(If multiple extensions with the same OID are present, at least one

extension must match).</p>

<example><title>Example</title>

SSLRequire "foobar" in PeerExtList("1.2.3.4.5.6")

</example>

<note><title>Notes on the PeerExtList function</title>

<ul>

<li><p>The object ID can be specified either as a descriptive

name recognized by the SSL library, such as <code>"nsComment"</code>,

or as a numeric OID, such as <code>"1.2.3.4.5.6"</code>.</p></li>

<li><p>Expressions with types known to the SSL library are rendered to

a string before comparison. For an extension with a type not

recognized by the SSL library, mod_ssl will parse the value if it is

one of the primitive ASN.1 types UTF8String, IA5String, VisibleString,

or BMPString. For an extension of one of these types, the string

value will be converted to UTF-8 if necessary, then compared against

the left-hand-side expression.</p></li>

</ul>

</note>

<note><title>SSLRequire is deprecated</title>

<p><code>SSLRequire</code> is deprecated and should in general be replaced

by <a href="mod_authz_core.html#reqexpr">Require expr</a>. The so called

<a href="/expr.html">ap_expr</a> syntax of <code>Require expr</code> is

a superset of the syntax of <code>SSLRequire</code>, with the following

exception:</p>

<p>In <code>SSLRequire</code>, the comparison operators <code>&lt;</code>,

<code>&lt;=</code>, ... are completely equivalent to the operators

<code>lt</code>, <code>le</code>, ... and work in a somewhat pecular way that

first compares the length of two strings and then the lexical order.

On the other hand, <a href="/expr.html">ap_expr</a> has two sets of

comparison operators: The operators <code>&lt;</code>,

<code>&lt;=</code>, ... do lexical string comparison, while the operators

<code>-lt</code>, <code>-le</code>, ... do integer comparison.

For the latter, there are also aliases without the leading dashes:

<code>lt</code>, <code>le</code>, ...

</p>

</note>

</usage>

<seealso><a href="/env.html">Environment Variables in Apache HTTP Server</a>,

for additional examples.

</seealso>

<seealso><a href="mod_authz_core.html#reqexpr">Require expr</a></seealso>

<seealso><a href="/expr.html">Generic expression syntax in Apache HTTP Server</a>

</seealso>

</directivesynopsis>

<directivesynopsis>

<name>SSLRenegBufferSize</name>

<description>Set the size for the SSL renegotiation buffer</description>

<syntax>SSLRenegBufferSize <var>bytes</var></syntax>

<default>SSLRenegBufferSize 131072</default>

<contextlist><context>directory</context>

<context>.htaccess</context></contextlist>

<override>AuthConfig</override>

<usage>

<p>If an SSL renegotiation is required in per-location context, for

example, any use of <directive

module="mod_ssl">SSLVerifyClient</directive> in a Directory or

Location block, then <module>mod_ssl</module> must buffer any HTTP

request body into memory until the new SSL handshake can be performed.

This directive can be used to set the amount of memory that will be

used for this buffer. </p>

<note type="warning"><p>

Note that in many configurations, the client sending the request body

will be untrusted so a denial of service attack by consumption of

memory must be considered when changing this configuration setting.

</p></note>

<example><title>Example</title>

SSLRenegBufferSize 262144

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStrictSNIVHostCheck</name>

<description>Whether to allow non-SNI clients to access a name-based virtual

host.

</description>

<syntax>SSLStrictSNIVHostCheck on|off</syntax>

<default>SSLStrictSNIVHostCheck off</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in Apache 2.2.12 and later</compatibility>

<usage>

<p>

This directive sets whether a non-SNI client is allowed to access a name-based

virtual host. If set to <code>on</code> in the default name-based virtual

host, clients that are SNI unaware will not be allowed to access <em>any</em>

virtual host, belonging to this particular IP / port combination.

If set to <code>on</code> in any other virtual host, SNI unaware clients

are not allowed to access this particular virtual host.

</p>

<note type="warning"><p>

This option is only available if httpd was compiled against an SNI capable

version of OpenSSL.

</p></note>

<example><title>Example</title>

SSLStrictSNIVHostCheck on

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyMachineCertificatePath</name>

<description>Directory of PEM-encoded client certificates and keys to be used by the proxy</description>

<syntax>SSLProxyMachineCertificatePath <em>directory</em></syntax>

<contextlist><context>server config</context></contextlist>

<override>Not applicable</override>

<usage>

<p>

This directive sets the directory where you keep the certificates and

keys used for authentication of the proxy server to remote servers.

</p>

<p>The files in this directory must be PEM-encoded and are accessed through

hash filenames. Additionally, you must create symbolic links named

<code><em>hash-value</em>.N</code>. And you should always make sure this

directory contains the appropriate symbolic links. Use the Makefile which

comes with mod_ssl to accomplish this task.

</p>

<note type="warning">

<p>Currently there is no support for encrypted private keys</p>

</note>

<example><title>Example</title>

SSLProxyMachineCertificatePath /usr/local/apache2/conf/proxy.crt/

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyMachineCertificateFile</name>

<description>File of concatenated PEM-encoded client certificates and keys to be used by the proxy</description>

<syntax>SSLProxyMachineCertificateFile <em>filename</em></syntax>

<contextlist><context>server config</context></contextlist>

<override>Not applicable</override>

<usage>

<p>

This directive sets the all-in-one file where you keep the certificates and

keys used for authentication of the proxy server to remote servers.

</p>

<p>

This referenced file is simply the concatenation of the various PEM-encoded

certificate files, in order of preference. Use this directive alternatively

or additionally to <code>SSLProxyMachineCertificatePath</code>.

</p>

<note type="warning">

<p>Currently there is no support for encrypted private keys</p>

</note>

<example><title>Example</title>

SSLProxyMachineCertificateFile /usr/local/apache2/conf/ssl.crt/proxy.pem

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyMachineCertificateChainFile</name>

<description>File of concatenated PEM-encoded CA certificates to be used by the proxy for choosing a certificate</description>

<syntax>SSLProxyMachineCertificateChainFile <em>filename</em></syntax>

<contextlist><context>server config</context></contextlist>

<override>Not applicable</override>

<usage>

<p>

This directive sets the all-in-one file where you keep the certificate chain

for all of the client certs in use. This directive will be needed if the

remote server presents a list of CA certificates that are not direct signers

of one of the configured client certificates.

</p>

<p>

This referenced file is simply the concatenation of the various PEM-encoded

certificate files. Upon startup, each client certificate configured will

be examined and a chain of trust will be constructed.

</p>

<note type="warning"><title>Security warning</title>

<p>If this directive is enabled, all of the certificates in the file will be

trusted as if they were also in <directive module="mod_ssl">

SSLProxyCACertificateFile</directive>.</p>

</note>

<example><title>Example</title>

SSLProxyMachineCertificateChainFile /usr/local/apache2/conf/ssl.crt/proxyCA.pem

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyVerify</name>

<description>Type of remote server Certificate verification</description>

<syntax>SSLProxyVerify <em>level</em></syntax>

<default>SSLProxyVerify none</default>

<contextlist><context>server config</context>

<context>virtual host</context> </contextlist>

<usage>

<p>When a proxy is configured to forward requests to a remote SSL

server, this directive can be used to configure certificate

verification of the remote server. </p>

<p>

The following levels are available for <em>level</em>:</p>

<ul>

<li><strong>none</strong>:

no remote server Certificate is required at all</li>

<li><strong>optional</strong>:

the remote server <em>may</em> present a valid Certificate</li>

<li><strong>require</strong>:

the remote server <em>has to</em> present a valid Certificate</li>

<li><strong>optional_no_ca</strong>:

the remote server may present a valid Certificate<br />

but it need not to be (successfully) verifiable.</li>

</ul>

<p>In practice only levels <strong>none</strong> and

<strong>require</strong> are really interesting, because level

<strong>optional</strong> doesn't work with all servers and level

<strong>optional_no_ca</strong> is actually against the idea of

authentication (but can be used to establish SSL test pages, etc.)</p>

<example><title>Example</title>

SSLProxyVerify require

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyVerifyDepth</name>

<description>Maximum depth of CA Certificates in Remote Server

Certificate verification</description>

<syntax>SSLProxyVerifyDepth <em>number</em></syntax>

<default>SSLProxyVerifyDepth 1</default>

<contextlist><context>server config</context>

<context>virtual host</context> </contextlist>

<usage>

<p>

This directive sets how deeply mod_ssl should verify before deciding that the

remote server does not have a valid certificate. </p>

<p>

The depth actually is the maximum number of intermediate certificate issuers,

i.e. the number of CA certificates which are max allowed to be followed while

verifying the remote server certificate. A depth of 0 means that self-signed

remote server certificates are accepted only, the default depth of 1 means

the remote server certificate can be self-signed or has to be signed by a CA

which is directly known to the server (i.e. the CA's certificate is under

<directive module="mod_ssl">SSLProxyCACertificatePath</directive>), etc.</p>

<example><title>Example</title>

SSLProxyVerifyDepth 10

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyCheckPeerExpire</name>

<description>Whether to check if remote server certificate is expired

</description>

<syntax>SSLProxyCheckPeerExpire on|off</syntax>

<default>SSLProxyCheckPeerExpire on</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets whether it is checked if the remote server certificate

is expired or not. If the check fails a 502 status code (Bad Gateway) is

sent.

</p>

<example><title>Example</title>

SSLProxyCheckPeerExpire on

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyCheckPeerCN</name>

<description>Whether to check the remote server certificates CN field

</description>

<syntax>SSLProxyCheckPeerCN on|off</syntax>

<default>SSLProxyCheckPeerCN on</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets whether the remote server certificates CN field is

compared against the hostname of the request URL. If both are not equal

a 502 status code (Bad Gateway) is sent.

</p>

<example><title>Example</title>

SSLProxyCheckPeerCN on

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyEngine</name>

<description>SSL Proxy Engine Operation Switch</description>

<syntax>SSLProxyEngine on|off</syntax>

<default>SSLProxyEngine off</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive toggles the usage of the SSL/TLS Protocol Engine for proxy. This

is usually used inside a <directive module="core"

type="section">VirtualHost</directive> section to enable SSL/TLS for proxy

usage in a particular virtual host. By default the SSL/TLS Protocol Engine is

disabled for proxy image both for the main server and all configured virtual hosts.</p>

<example><title>Example</title>

&lt;VirtualHost _default_:443&gt;<br />

SSLProxyEngine on<br />

...<br />

&lt;/VirtualHost&gt;

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyProtocol</name>

<description>Configure usable SSL protocol flavors for proxy usage</description>

<syntax>SSLProxyProtocol [+|-]<em>protocol</em> ...</syntax>

<default>SSLProxyProtocol all</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<override>Options</override>

<usage>

<p>

This directive can be used to control the SSL protocol flavors mod_ssl should

use when establishing its server environment for proxy . It will only connect

to servers using one of the provided protocols.</p>

<p>Please refer to <directive module="mod_ssl">SSLProtocol</directive>

for additional information.

</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyCipherSuite</name>

<description>Cipher Suite available for negotiation in SSL

proxy handshake</description>

<syntax>SSLProxyCipherSuite <em>cipher-spec</em></syntax>

<default>SSLProxyCipherSuite ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context></contextlist>

<override>AuthConfig</override>

<usage>

<p>Equivalent to <code>SSLCipherSuite</code>, but for the proxy connection.

Please refer to <directive module="mod_ssl">SSLCipherSuite</directive>

for additional information.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyCACertificatePath</name>

<description>Directory of PEM-encoded CA Certificates for

Remote Server Auth</description>

<syntax>SSLProxyCACertificatePath <em>directory-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the directory where you keep the Certificates of

Certification Authorities (CAs) whose remote servers you deal with. These are used to

verify the remote server certificate on Remote Server Authentication.</p>

<p>

The files in this directory have to be PEM-encoded and are accessed through

hash filenames. So usually you can't just place the Certificate files

there: you also have to create symbolic links named

<em>hash-value</em><code>.N</code>. And you should always make sure this directory

contains the appropriate symbolic links. Use the <code>Makefile</code> which

comes with mod_ssl to accomplish this task.</p>

<example><title>Example</title>

SSLProxyCACertificatePath /usr/local/apache2/conf/ssl.crt/

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyCACertificateFile</name>

<description>File of concatenated PEM-encoded CA Certificates

for Remote Server Auth</description>

<syntax>SSLProxyCACertificateFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the <em>all-in-one</em> file where you can assemble the

Certificates of Certification Authorities (CA) whose <em>remote servers</em> you deal

with. These are used for Remote Server Authentication. Such a file is simply the

concatenation of the various PEM-encoded Certificate files, in order of

preference. This can be used alternatively and/or additionally to

<directive module="mod_ssl">SSLProxyCACertificatePath</directive>.</p>

<example><title>Example</title>

SSLProxyCACertificateFile /usr/local/apache2/conf/ssl.crt/ca-bundle-remote-server.crt

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyCARevocationPath</name>

<description>Directory of PEM-encoded CA CRLs for

Remote Server Auth</description>

<syntax>SSLProxyCARevocationPath <em>directory-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the directory where you keep the Certificate Revocation

Lists (CRL) of Certification Authorities (CAs) whose remote servers you deal with.

These are used to revoke the remote server certificate on Remote Server Authentication.</p>

<p>

The files in this directory have to be PEM-encoded and are accessed through

hash filenames. So usually you have not only to place the CRL files there.

Additionally you have to create symbolic links named

<em>hash-value</em><code>.rN</code>. And you should always make sure this directory

contains the appropriate symbolic links. Use the <code>Makefile</code> which

comes with <module>mod_ssl</module> to accomplish this task.</p>

<example><title>Example</title>

SSLProxyCARevocationPath /usr/local/apache2/conf/ssl.crl/

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyCARevocationFile</name>

<description>File of concatenated PEM-encoded CA CRLs for

Remote Server Auth</description>

<syntax>SSLProxyCARevocationFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

This directive sets the <em>all-in-one</em> file where you can

assemble the Certificate Revocation Lists (CRL) of Certification

Authorities (CA) whose <em>remote servers</em> you deal with. These are used

for Remote Server Authentication. Such a file is simply the concatenation of

the various PEM-encoded CRL files, in order of preference. This can be

used alternatively and/or additionally to <directive

module="mod_ssl">SSLProxyCARevocationPath</directive>.</p>

<example><title>Example</title>

SSLProxyCARevocationFile /usr/local/apache2/conf/ssl.crl/ca-bundle-remote-server.crl

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLProxyCARevocationCheck</name>

<description>Enable CRL-based revocation checking for Remote Server Auth</description>

<syntax>SSLProxyCARevocationCheck chain|leaf|none</syntax>

<default>SSLProxyCARevocationCheck none</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<usage>

<p>

Enables certificate revocation list (CRL) checking for the

<em>remote servers</em> you deal with. At least one of

<directive module="mod_ssl">SSLProxyCARevocationFile</directive>

or <directive module="mod_ssl">SSLProxyCARevocationPath</directive> must be

configured. When set to <code>chain</code> (recommended setting),

CRL checks are applied to all certificates in the chain, while setting it to

<code>leaf</code> limits the checks to the end-entity cert.

</p>

<note>

<title>When set to <code>chain</code> or <code>leaf</code>,

CRLs <em>must</em> be available for successful validation</title>

<p>

Prior to version 2.3.15, CRL checking in mod_ssl also succeeded when

no CRL(s) were found in any of the locations configured with

<directive module="mod_ssl">SSLProxyCARevocationFile</directive>

or <directive module="mod_ssl">SSLProxyCARevocationPath</directive>.

With the introduction of this directive, the behavior has been changed:

when checking is enabled, CRLs <em>must</em> be present for the validation

to succeed - otherwise it will fail with an

<code>"unable to get certificate CRL"</code> error.

</p>

</note>

<example><title>Example</title>

SSLProxyCARevocationCheck chain

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLUserName</name>

<description>Variable name to determine user name</description>

<syntax>SSLUserName <em>varname</em></syntax>

<contextlist><context>server config</context>

<context>directory</context>

<context>.htaccess</context></contextlist>

<override>AuthConfig</override>

<compatibility>Available in Apache 2.0.51 and later</compatibility>

<usage>

<p>

This directive sets the "user" field in the Apache request object.

This is used by lower modules to identify the user with a character

string. In particular, this may cause the environment variable

<code>REMOTE_USER</code> to be set. The <em>varname</em> can be

any of the <a href="#envvars">SSL environment variables</a>.</p>

<p>Note that this directive has no effect if the

<code>FakeBasicAuth</code> option is used (see <a

href="#ssloptions">SSLOptions</a>).</p>

<example><title>Example</title>

SSLUserName SSL_CLIENT_S_DN_CN

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLHonorCipherOrder</name>

<description>Option to prefer the server's cipher preference order</description>

<syntax>SSLHonorCipherOrder <em>flag</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in Apache 2.1 and later, if using OpenSSL 0.9.7 or later</compatibility>

<usage>

<p>When choosing a cipher during an SSLv3 or TLSv1 handshake, normally

the client's preference is used. If this directive is enabled, the

server's preference will be used instead.</p>

<example><title>Example</title>

SSLHonorCipherOrder on

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLCryptoDevice</name>

<description>Enable use of a cryptographic hardware accelerator</description>

<syntax>SSLCryptoDevice <em>engine</em></syntax>

<default>SSLCryptoDevice builtin</default>

<contextlist><context>server config</context></contextlist>

<usage>

<p>

This directive enables use of a cryptographic hardware accelerator

board to offload some of the SSL processing overhead. This directive

can only be used if the SSL toolkit is built with "engine" support;

OpenSSL 0.9.7 and later releases have "engine" support by default, the

separate "-engine" releases of OpenSSL 0.9.6 must be used.</p>

<p>To discover which engine names are supported, run the command

&quot;<code>openssl engine</code>&quot;.</p>

<example><title>Example</title>

# For a Broadcom accelerator:<br />

SSLCryptoDevice ubsec

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLOCSPEnable</name>

<description>Enable OCSP validation of the client certificate chain</description>

<syntax>SSLOCSPEnable <em>flag</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3 and later, if using OpenSSL 0.9.7 or later</compatibility>

<usage>

<p>This option enables OCSP validation of the client certificate

chain. If this option is enabled, certificates in the client's

certificate chain will be validated against an OCSP responder after

normal verification (including CRL checks) have taken place.</p>

<p>The OCSP responder used is either extracted from the certificate

itself, or derived by configuration; see the

<directive module="mod_ssl">SSLOCSPDefaultResponder</directive> and

<directive module="mod_ssl">SSLOCSPOverrideResponder</directive>

directives.</p>

<example><title>Example</title>

SSLVerifyClient on<br/>

SSLOCSPEnable on<br/>

SSLOCSPDefaultResponder http://responder.example.com:8888/responder<br/>

SSLOCSPOverrideResponder on

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLOCSPDefaultResponder</name>

<description>Set the default responder URI for OCSP validation</description>

<syntax>SSLOCSDefaultResponder <em>uri</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3 and later, if using OpenSSL 0.9.7 or later</compatibility>

<usage>

<p>This option sets the default OCSP responder to use. If <directive

module="mod_ssl">SSLOCSPOverrideResponder</directive> is not enabled,

the URI given will be used only if no responder URI is specified in

the certificate being verified.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLOCSPOverrideResponder</name>

<description>Force use of the default responder URI for OCSP validation</description>

<syntax>SSLOCSPOverrideResponder <em>flag</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3 and later, if using OpenSSL 0.9.7 or later</compatibility>

<usage>

<p>This option forces the configured default OCSP responder to be used

during OCSP certificate validation, regardless of whether the

certificate being validated references an OCSP responder.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLOCSPResponseTimeSkew</name>

<description>Maximum allowable time skew for OCSP response validation</description>

<syntax>SSLOCSPResponseTimeSkew <em>seconds</em></syntax>

<default>SSLOCSPResponseTimeSkew 300</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3 and later, if using OpenSSL 0.9.7 or later</compatibility>

<usage>

<p>This option sets the maximum allowable time skew for OCSP responses

(when checking their <code>thisUpdate</code> and <code>nextUpdate</code> fields).</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLOCSPResponseMaxAge</name>

<description>Maximum allowable age for OCSP responses</description>

<syntax>SSLOCSPResponseMaxAge <em>seconds</em></syntax>

<default>SSLOCSPResponseMaxAge -1</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3 and later, if using OpenSSL 0.9.7 or later</compatibility>

<usage>

<p>This option sets the maximum allowable age ("freshness") for OCSP responses.

The default value (<code>-1</code>) does not enforce a maximum age,

which means that OCSP responses are considered valid as long as their

<code>nextUpdate</code> field is in the future.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLOCSPResponderTimeout</name>

<description>Timeout for OCSP queries</description>

<syntax>SSLOCSPResponderTimeout <em>seconds</em></syntax>

<default>SSLOCSPResponderTimeout 10</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3 and later, if using OpenSSL 0.9.7 or later</compatibility>

<usage>

<p>This option sets the timeout for queries to OCSP responders, when

<directive module="mod_ssl">SSLOCSPEnable</directive> is turned on.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLInsecureRenegotiation</name>

<description>Option to enable support for insecure renegotiation</description>

<syntax>SSLInsecureRenegotiation <em>flag</em></syntax>

<default>SSLInsecureRenegotiation off</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.2.15 and later, if using OpenSSL 0.9.8m or later</compatibility>

<usage>

<p>As originally specified, all versions of the SSL and TLS protocols

(up to and including TLS/1.2) were vulnerable to a Man-in-the-Middle

attack

(<a href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2009-3555">CVE-2009-3555</a>)

during a renegotiation. This vulnerability allowed an attacker to

"prefix" a chosen plaintext to the HTTP request as seen by the web

server. A protocol extension was developed which fixed this

vulnerability if supported by both client and server.</p>

<p>If <module>mod_ssl</module> is linked against OpenSSL version 0.9.8m

or later, by default renegotiation is only supported with

clients supporting the new protocol extension. If this directive is

enabled, renegotiation will be allowed with old (unpatched) clients,

albeit insecurely.</p>

<note type="warning"><title>Security warning</title>

<p>If this directive is enabled, SSL connections will be vulnerable to

the Man-in-the-Middle prefix attack as described

in <a href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2009-3555">CVE-2009-3555</a>.</p>

</note>

<example><title>Example</title>

SSLInsecureRenegotiation on

</example>

<p>The <code>SSL_SECURE_RENEG</code> environment variable can be used

from an SSI or CGI script to determine whether secure renegotiation is

supported for a given SSL connection.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLUseStapling</name>

<description>Enable stapling of OCSP responses in the TLS handshake</description>

<syntax>SSLUseStapling on|off</syntax>

<default>SSLUseStapling off</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>This option enables OCSP stapling, as defined by the "Certificate

Status Request" TLS extension specified in RFC 6066. If enabled (and

requested by the client), mod_ssl will include an OCSP response

for its own certificate in the TLS handshake. Configuring an

<directive module="mod_ssl">SSLStaplingCache</directive> is a

prerequisite for enabling OCSP stapling.</p>

<p>OCSP stapling relieves the client of querying the OCSP responder

on its own, but it should be noted that in its current specification,

the server's <code>CertificateStatus</code> reply may only include an

OCSP response for a single cert. For server certificates with intermediate

CA certificates in their chain (the typical case nowadays),

stapling in its current form therefore only partially achieves the

stated goal of "saving roundtrips and resources" - see also the <a

href="https://datatracker.ietf.org/doc/draft-pettersen-tls-ext-multiple-ocsp/">

"Adding Multiple TLS Certificate Status Extension requests"</a> Internet draft.

</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingCache</name>

<description>Configures the OCSP stapling cache</description>

<syntax>SSLStaplingCache <em>type</em></syntax>

<contextlist><context>server config</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>Configures the cache used to store OCSP responses which get included

in the TLS handshake if <directive module="mod_ssl">SSLUseStapling</directive>

is enabled. Configuration of a cache is mandatory for OCSP stapling.

With the exception of <code>none</code> and <code>nonenotnull</code>,

the same storage types are supported as with

<directive module="mod_ssl">SSLSessionCache</directive>.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingResponseTimeSkew</name>

<description>Maximum allowable time skew for OCSP stapling response validation</description>

<syntax>SSLStaplingResponseTimeSkew <em>seconds</em></syntax>

<default>SSLStaplingResponseTimeSkew 300</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>This option sets the maximum allowable time skew when mod_ssl checks the

<code>thisUpdate</code> and <code>nextUpdate</code> fields of OCSP responses

which get included in the TLS handshake (OCSP stapling). Only applicable

if <directive module="mod_ssl">SSLUseStapling</directive> is turned on.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingResponderTimeout</name>

<description>Timeout for OCSP stapling queries</description>

<syntax>SSLStaplingResponderTimeout <em>seconds</em></syntax>

<default>SSLStaplingResponderTimeout 10</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>This option sets the timeout for queries to OCSP responders when

<directive module="mod_ssl">SSLUseStapling</directive> is enabled

and mod_ssl is querying a responder for OCSP stapling purposes.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingResponseMaxAge</name>

<description>Maximum allowable age for OCSP stapling responses</description>

<syntax>SSLStaplingResponseMaxAge <em>seconds</em></syntax>

<default>SSLStaplingResponseMaxAge -1</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>This option sets the maximum allowable age ("freshness") when

considering OCSP responses for stapling purposes, i.e. when

<directive module="mod_ssl">SSLUseStapling</directive> is turned on.

The default value (<code>-1</code>) does not enforce a maximum age,

which means that OCSP responses are considered valid as long as their

<code>nextUpdate</code> field is in the future.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingStandardCacheTimeout</name>

<description>Number of seconds before expiring responses in the OCSP stapling cache</description>

<syntax>SSLStaplingStandardCacheTimeout <em>seconds</em></syntax>

<default>SSLStaplingStandardCacheTimeout 3600</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>Sets the timeout in seconds before responses in the OCSP stapling cache

(configured through <directive module="mod_ssl">SSLStaplingCache</directive>)

will expire. This directive applies to <em>valid</em> responses, while

<directive module="mod_ssl">SSLStaplingErrorCacheTimeout</directive> is

used for controlling the timeout for invalid/unavailable responses.

</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingReturnResponderErrors</name>

<description>Pass stapling related OCSP errors on to client</description>

<syntax>SSLStaplingReturnResponderErrors on|off</syntax>

<default>SSLStaplingReturnResponderErrors on</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>When enabled, mod_ssl will pass responses from unsuccessful

stapling related OCSP queries (such as status errors, expired responses etc.)

on to the client. If set to <code>off</code>, no stapled responses

for failed queries will be included in the TLS handshake.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingFakeTryLater</name>

<description>Synthesize "tryLater" responses for failed OCSP stapling queries</description>

<syntax>SSLStaplingFakeTryLater on|off</syntax>

<default>SSLStaplingFakeTryLater on</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>When enabled and a query to an OCSP responder for stapling

purposes fails, mod_ssl will synthesize a "tryLater" response for the

client. Only effective if <directive

module="mod_ssl">SSLStaplingReturnResponderErrors</directive>

is also enabled.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingErrorCacheTimeout</name>

<description>Number of seconds before expiring invalid responses in the OCSP stapling cache</description>

<syntax>SSLStaplingErrorCacheTimeout <em>seconds</em></syntax>

<default>SSLStaplingErrorCacheTimeout 600</default>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>Sets the timeout in seconds before <em>invalid</em> responses

in the OCSP stapling cache (configured through <directive

module="mod_ssl">SSLStaplingCache</directive>) will expire.

To set the cache timeout for valid responses, see

<directive module="mod_ssl">SSLStaplingStandardCacheTimeout</directive>.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLStaplingForceURL</name>

<description>Override the OCSP responder URI specified in the certificate's AIA extension</description>

<syntax>SSLStaplingForceURL <em>uri</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.3.3 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>This directive overrides the URI of an OCSP responder as obtained from

the authorityInfoAccess (AIA) extension of the certificate.

Of potential use when going through a proxy for retrieving OCSP queries.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SSLSessionTicketKeyFile</name>

<description>Persistent encryption/decryption key for TLS session tickets</description>

<syntax>SSLSessionTicketKeyFile <em>file-path</em></syntax>

<contextlist><context>server config</context>

<context>virtual host</context></contextlist>

<compatibility>Available in httpd 2.4.0 and later, if using OpenSSL 0.9.8h or later</compatibility>

<usage>

<p>Optionally configures a secret key for encrypting and decrypting

TLS session tickets, as defined in

<a href="http://www.ietf.org/rfc/rfc5077.txt">RFC 5077</a>.

Primarily suitable for clustered environments where TLS sessions information

should be shared between multiple nodes. For single-instance httpd setups,

it is recommended to <em>not</em> configure a ticket key file, but to

rely on (random) keys generated by mod_ssl at startup, instead.</p>

<p>The ticket key file must contain 48 bytes of random data,

preferrably created from a high-entropy source. On a Unix-based system,

a ticket key file can be created as follows:</p>

<example>

dd if=/dev/random of=/path/to/file.tkey bs=1 count=48

</example>

<p>Ticket keys should be rotated (replaced) on a frequent basis,

as this is the only way to invalidate an existing session ticket -

OpenSSL currently doesn't allow to specify a limit for ticket lifetimes.</p>

<note type="warning">

<p>The ticket key file contains sensitive keying material and should

be protected with file permissions similar to those used for

<directive module="mod_ssl">SSLCertificateKeyFile</directive>.</p>

</note>

</usage>

</directivesynopsis>

</modulesynopsis>