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你可能喜欢mod_ssl - Apache HTTP Server Version 2.2
Please note
This document refers to a legacy release (2.2) of Apache httpd. The active release (2.4) is documented . If you have not already upgraded, please follow
for more information.
You may follow
to go to the current version of this document.Apache Module mod_ssl
Available Languages:
Strong cryptography using the Secure Sockets
Layer (SSL) and Transport Layer Security (TLS) protocols
ssl_module
This module provides SSL v2/v3 and TLS v1 support for the Apache
HTTP Server.
It was contributed by Ralf S. Engeschall based on his
mod_ssl project and originally derived from work by Ben Laurie.
This module relies on
to provide the cryptography engine.
Further details, discussion, and examples are provided in the
Directives
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
SSLOptions 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
chapter for details on the
compatibility variables.
Value Type:
Description:
HTTPS is being used.
SSL_PROTOCOL
The SSL protocol version (SSLv2, SSLv3, TLSv1, TLSv1.1, TLSv1.2)
SSL_SESSION_ID
The hex-encoded SSL session id
SSL_CIPHER
The cipher specification name
SSL_CIPHER_EXPORT
true if cipher is an export cipher
SSL_CIPHER_USEKEYSIZE
Number of cipher bits (actually used)
SSL_CIPHER_ALGKEYSIZE
Number of cipher bits (possible)
SSL_COMPRESS_METHOD
SSL compression method negotiated
SSL_VERSION_INTERFACE
The mod_ssl program version
SSL_VERSION_LIBRARY
The OpenSSL program version
SSL_CLIENT_M_VERSION
The version of the client certificate
SSL_CLIENT_M_SERIAL
The serial of the client certificate
SSL_CLIENT_S_DN
Subject DN in client's certificate
SSL_CLIENT_S_DN_x509 string
Component of client's Subject DN
SSL_CLIENT_I_DN
Issuer DN of client's certificate
SSL_CLIENT_I_DN_x509 string
Component of client's Issuer DN
SSL_CLIENT_V_START
Validity of client's certificate (start time)
SSL_CLIENT_V_END
Validity of client's certificate (end time)
SSL_CLIENT_V_REMAIN
Number of days until client's certificate expires
SSL_CLIENT_A_SIG
Algorithm used for the signature of client's certificate
SSL_CLIENT_A_KEY
Algorithm used for the public key of client's certificate
SSL_CLIENT_CERT
PEM-encoded client certificate
SSL_CLIENT_CERT_CHAIN_n string
PEM-encoded certificates in client certificate chain
SSL_CLIENT_VERIFY
NONE, SUCCESS, GENEROUS or FAILED:reason
SSL_SERVER_M_VERSION
The version of the server certificate
SSL_SERVER_M_SERIAL
The serial of the server certificate
SSL_SERVER_S_DN
Subject DN in server's certificate
SSL_SERVER_S_DN_x509 string
Component of server's Subject DN
SSL_SERVER_I_DN
Issuer DN of server's certificate
SSL_SERVER_I_DN_x509 string
Component of server's Issuer DN
SSL_SERVER_V_START
Validity of server's certificate (start time)
SSL_SERVER_V_END
Validity of server's certificate (end time)
SSL_SERVER_A_SIG
Algorithm used for the signature of server's certificate
SSL_SERVER_A_KEY
Algorithm used for the public key of server's certificate
SSL_SERVER_CERT
PEM-encoded server certificate
SSL_TLS_SNI
Contents of the SNI TLS extension (if supplied with ClientHello)
x509 specifies a component of an X.509 DN; one of
C,ST,L,O,OU,CN,T,I,G,S,D,UID,Email.
In Apache 2.1 and
later, x509 may also include a numeric _n
If the DN in question contains multiple attributes of the
same name, this suffix is used as an index to select a particular
attribute.
For example, where the server certificate subject DN
included two OU fields, SSL_SERVER_S_DN_OU_0 and
SSL_SERVER_S_DN_OU_1 could be used to reference each.
SSL_CLIENT_V_REMAIN is only available in version 2.1
and later.
is built into Apache or at least
loaded (under DSO situation) additional functions exist for the
. First there is an
additional ``%{varname}x''
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.
For backward compatibility there is additionally a special
``%{name}c'' cryptography format function
provided. Information about this function is provided in the
CustomLog logs/ssl_request_log \
"%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"
These formats even work without setting the StdEnvVars
option of the
directive.
File of concatenated PEM-encoded CA Certificates
for Client Auth
SSLCACertificateFile file-path
server config, virtual host
This directive sets the all-in-one file where you can assemble the
Certificates of Certification Authorities (CA) whose clients 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
SSLCACertificateFile /usr/local/apache2/conf/ssl.crt/ca-bundle-client.crt
Directory of PEM-encoded CA Certificates for
Client Auth
SSLCACertificatePath directory-path
server config, virtual host
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.
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
hash-value.N. And you should always make sure this directory
contains the appropriate symbolic links.
SSLCACertificatePath /usr/local/apache2/conf/ssl.crt/
File of concatenated PEM-encoded CA Certificates
for defining acceptable CA names
SSLCADNRequestFile file-path
server config, virtual host
When a client certificate is requested by mod_ssl, a list of
acceptable Certificate Authority names 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.
If neither of the directives
are given, then the
set of acceptable CA names sent to the client is the names of all the
CA certificates given by the
words, the names of the CAs which will actually be used to verify the
client certificate.
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,
acceptable CA names are then taken from the complete set of
certificates in the directory and/or file specified by this pair of
directives.
specify an all-in-one file containing a concatenation of
PEM-encoded CA certificates.
SSLCADNRequestFile /usr/local/apache2/conf/ca-names.crt
Directory of PEM-encoded CA Certificates for
defining acceptable CA names
SSLCADNRequestPath directory-path
server config, virtual host
This optional directive can be used to specify the set of
acceptable CA names which will be sent to the client when a
client certificate is requested.
directive for more
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
hash-value.N. And you should always make sure
this directory contains the appropriate symbolic links.
SSLCADNRequestPath /usr/local/apache2/conf/ca-names.crt/
File of concatenated PEM-encoded CA CRLs for
Client Auth
SSLCARevocationFile file-path
server config, virtual host
This directive sets the all-in-one file where you can
assemble the Certificate Revocation Lists (CRL) of Certification
Authorities (CA) whose clients 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 .
SSLCARevocationFile /usr/local/apache2/conf/ssl.crl/ca-bundle-client.crl
Directory of PEM-encoded CA CRLs for
Client Auth
SSLCARevocationPath directory-path
server config, virtual host
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.
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
hash-value.rN. And you should always make sure this directory
contains the appropriate symbolic links.
SSLCARevocationPath /usr/local/apache2/conf/ssl.crl/
File of PEM-encoded Server CA Certificates
SSLCertificateChainFile file-path
server config, virtual host
This directive sets the optional all-in-one 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.
This should be used alternatively and/or additionally to
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
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.
But be careful: Providing the certificate chain works only if you are using a
single RSA or DSA based server certificate. If you are
using a coupled RSA+DSA certificate pair, this will work only if actually both
certificates use the same certificate chain. Else the browsers will be
confused in this situation.
SSLCertificateChainFile /usr/local/apache2/conf/ssl.crt/ca.crt
Server PEM-encoded X.509 Certificate file
SSLCertificateFile file-path
server config, virtual host
ECC support is available in Apache 2.2.26 and later
This directive points to a file with certificate data in PEM format.
At a minimum, the file must include an end-entity (leaf) certificate.
The directive can be used up to three times (referencing different filenames)
when an RSA, a DSA, and an ECC based server certificate is used in parallel.
Custom DH parameters and an EC curve name for ephemeral keys,
can be added to end of the first file configured using
This is supported in version 2.2.30 or later.
Such parameters can be generated using the commands
openssl dhparam and openssl ecparam.
The parameters can be added as-is to the end of the first
certificate file. Only the first file can be used for custom
parameters, as they are applied independently of the authentication
algorithm type.
Finally the the end-entity certificate's private key can also be
added to the certificate file instead of using a separate
directive. This practice is highly discouraged. If the private
key is encrypted, the pass phrase dialog is forced at startup time.
DH parameter interoperability with primes & 1024 bit
Beginning with version 2.2.30, mod_ssl makes use of
standardized DH parameters with prime lengths of ,
8192 bits (from ),
and hands them out to clients based on the length of the certificate's RSA/DSA
With Java-based clients in particular (Java 7 or earlier), this may lead
to handshake failures - see this
for working around
such issues.
SSLCertificateFile /usr/local/apache2/conf/ssl.crt/server.crt
Server PEM-encoded Private Key file
SSLCertificateKeyFile file-path
server config, virtual host
ECC support is available in Apache 2.2.26 and later
This directive points to the PEM-encoded private key file for the
server. If the contained private key is encrypted, the pass phrase
dialog is forced at startup time.
The directive can be used up to three times (referencing different filenames)
when an RSA, a DSA, and an ECC based private key is used in parallel. For each
directive, there must be a matching SSLCertificateFile
directive.
The private key may also be combined with the certificate in the file given by
, but this practice
is highly discouraged.
SSLCertificateKeyFile /usr/local/apache2/conf/ssl.key/server.key
Cipher Suite available for negotiation in SSL
SSLCipherSuite cipher-spec
SSLCipherSuite ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP
server config, virtual host, directory, .htaccess
AuthConfig
This complex directive uses a colon-separated cipher-spec 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.
An SSL cipher specification in cipher-spec is composed of 4 major
attributes plus a few extra minor ones:
Key Exchange Algorithm:
RSA or Diffie-Hellman variants.
Authentication Algorithm:
RSA, Diffie-Hellman, DSS or none.
Cipher/Encryption Algorithm:
DES, Triple-DES, RC4, RC2, IDEA or none.
MAC Digest Algorithm:
MD5, SHA or SHA1.
An SSL cipher can also be an export cipher and is either a 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 ).
Description
Key Exchange Algorithm:
RSA key exchange
Diffie-Hellman key exchange with RSA key
Diffie-Hellman key exchange with DSA key
Ephemeral (temp.key) Diffie-Hellman key exchange (no cert)
Authentication Algorithm:
No authentication
RSA authentication
DSS authentication
Diffie-Hellman authentication
Cipher Encoding Algorithm:
No encoding
DES encoding
Triple-DES encoding
RC4 encoding
RC2 encoding
IDEA encoding
MAC Digest Algorithm:
MD5 hash function
SHA1 hash function
SHA hash function
all SSL version 2.0 ciphers
all SSL version 3.0 ciphers
all TLS version 1.0 ciphers
all export ciphers
EXPORT40 all 40-bit export ciphers only
EXPORT56 all 56-bit export ciphers only
all low strength ciphers (no export, single DES)
MEDIUM all ciphers with 128 bit encryption
all ciphers using Triple-DES
all ciphers using RSA key exchange
all ciphers using Diffie-Hellman key exchange
all ciphers using Ephemeral Diffie-Hellman key exchange
all ciphers using Anonymous Diffie-Hellman key exchange
all ciphers using DSS authentication
all ciphers using no encryption
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 (SSLv2, SSLv3, TLSv1, EXP, LOW, MEDIUM,
HIGH) for certain groups of ciphers. These tags can be joined
together with prefixes to form the cipher-spec. Available
prefixes are:
none: add cipher to list
+: move matching ciphers to the current location in list
-: remove cipher from list (can be added later again)
!: kill cipher from list completely (can not be added later again)
aNULL, eNULL and EXP
ciphers are always disabled
Beginning with version 2.2.30, null and export-grade
ciphers are always disabled, as mod_ssl unconditionally prepends any supplied
cipher suite string with !aNULL:!eNULL:!EXP: at initialization.
A simpler way to look at all of this is to use the ``openssl ciphers
-v'' command which provides a nice way to successively create the
correct cipher-spec string. The default cipher-spec string
is ``ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP'' which
means the following: first, remove from consideration any ciphers that do not
authenticate, i.e. for SSL only the Anonymous Diffie-Hellman ciphers. Next,
use ciphers using RC4 and RSA. Next include the high, medium and then the low
security ciphers. Finally pull all SSLv2 and export ciphers to the
end of the list.
$ openssl ciphers -v 'ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP'
SSLv3 Kx=RSA
SSLv3 Kx=RSA
EDH-RSA-DES-CBC3-SHA
SSLv3 Kx=DH
Enc=3DES(168) Mac=SHA1
EXP-RC4-MD5
SSLv3 Kx=RSA(512) Au=RSA
Enc=RC4(40)
EXP-RC2-CBC-MD5
SSLv2 Kx=RSA(512) Au=RSA
Enc=RC2(40)
EXP-RC4-MD5
SSLv2 Kx=RSA(512) Au=RSA
Enc=RC4(40)
The complete list of particular RSA & DH ciphers for SSL is given in .
SSLCipherSuite RSA:!EXP:!NULL:+HIGH:+MEDIUM:-LOW
Protocol Key Ex. Auth. Enc. MAC Type
RSA Ciphers:
DES-CBC3-SHA SSLv3 RSA RSA 3DES(168) SHA1
DES-CBC3-MD5 SSLv2 RSA RSA 3DES(168) MD5
IDEA-CBC-SHA SSLv3 RSA RSA IDEA(128) SHA1
RC4-SHA SSLv3 RSA RSA RC4(128) SHA1
RC4-MD5 SSLv3 RSA RSA RC4(128) MD5
IDEA-CBC-MD5 SSLv2 RSA RSA IDEA(128) MD5
RC2-CBC-MD5 SSLv2 RSA RSA RC2(128) MD5
RC4-MD5 SSLv2 RSA RSA RC4(128) MD5
DES-CBC-SHA SSLv3 RSA RSA DES(56) SHA1
RC4-64-MD5 SSLv2 RSA RSA RC4(64) MD5
DES-CBC-MD5 SSLv2 RSA RSA DES(56) MD5
EXP-DES-CBC-SHA SSLv3 RSA(512) RSA DES(40) SHA1
EXP-RC2-CBC-MD5 SSLv3 RSA(512) RSA RC2(40) MD5
EXP-RC4-MD5 SSLv3 RSA(512) RSA RC4(40) MD5
EXP-RC2-CBC-MD5 SSLv2 RSA(512) RSA RC2(40) MD5
EXP-RC4-MD5 SSLv2 RSA(512) RSA RC4(40) MD5
NULL-SHA SSLv3 RSA RSA None SHA1
NULL-MD5 SSLv3 RSA RSA None MD5
Diffie-Hellman Ciphers:
ADH-DES-CBC3-SHA SSLv3 DH None 3DES(168) SHA1
ADH-DES-CBC-SHA SSLv3 DH None DES(56) SHA1
ADH-RC4-MD5 SSLv3 DH None RC4(128) MD5
EDH-RSA-DES-CBC3-SHA SSLv3 DH RSA 3DES(168) SHA1
EDH-DSS-DES-CBC3-SHA SSLv3 DH DSS 3DES(168) SHA1
EDH-RSA-DES-CBC-SHA SSLv3 DH RSA DES(56) SHA1
EDH-DSS-DES-CBC-SHA SSLv3 DH DSS DES(56) SHA1
EXP-EDH-RSA-DES-CBC-SHA SSLv3 DH(512) RSA DES(40) SHA1
EXP-EDH-DSS-DES-CBC-SHA SSLv3 DH(512) DSS DES(40) SHA1
EXP-ADH-DES-CBC-SHA SSLv3 DH(512) None DES(40) SHA1
EXP-ADH-RC4-MD5 SSLv3 DH(512) None RC4(40) MD5
Enable compression on the SSL level
SSLCompression on|off
SSLCompression off
server config, virtual host
Available in httpd 2.2.24 and later, if using OpenSSL 0.9.8
virtual host scope available if using OpenSSL 1.0.0 or later.
The default used to be on in versions 2.2.24 to 2.2.25.
This directive allows to enable compression on the SSL level.
Enabling compression causes security issues in most setups (the so called
CRIME attack).
Enable use of a cryptographic hardware accelerator
SSLCryptoDevice engine
SSLCryptoDevice builtin
server config
Available in Apache 2.1 and later, if using -engine flavor of OpenSSL
0.9.6, or OpenSSL 0.9.7 or later
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"
OpenSSL 0.9.7 and later releases have "engine" support by default, the
separate "-engine" releases of OpenSSL 0.9.6 must be used.
To discover which engine names are supported, run the command
"openssl engine".
# For a Broadcom accelerator:
SSLCryptoDevice ubsec
SSL Engine Operation Switch
SSLEngine on|off|optional
SSLEngine off
server config, virtual host
This directive toggles the usage of the SSL/TLS Protocol Engine. This
should be used inside a
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.
&VirtualHost _default_:443&
SSLEngine on
&/VirtualHost&
In Apache 2.1 and later, SSLEngine can be set to
optional. This enables support for
, Upgrading to TLS
Within HTTP/1.1. At this time no web browsers support RFC 2817.
SSL FIPS mode Switch
SSLFIPS on|off
SSLFIPS off
server config
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
The mode applies to all SSL library operations.
If httpd was compiled against an SSL library which did not support
the FIPS_mode flag, SSLFIPS on 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
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.
Option to prefer the server's cipher preference order
SSLHonorCipherOrder flag
server config, virtual host
Available in Apache 2.1 and later, if using OpenSSL 0.9.7 or later
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.
SSLHonorCipherOrder on
Option to enable support for insecure renegotiation
SSLInsecureRenegotiation flag
SSLInsecureRenegotiation off
server config, virtual host
Available in httpd 2.2.15 and later, if using OpenSSL 0.9.8m or later
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
during a renegotiation.
This vulnerability allowed an attacker to
"prefix" a chosen plaintext to the HTTP request as seen by the web
A protocol extension was developed which fixed this
vulnerability if supported by both client and server.
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.
Security warning
If this directive is enabled, SSL connections will be vulnerable to
the Man-in-the-Middle prefix attack as described
SSLInsecureRenegotiation on
The SSL_SECURE_RENEG environment variable can be used
from an SSI or CGI script to determine whether secure renegotiation is
supported for a given SSL connection.
Semaphore for internal mutual exclusion of
operations
SSLMutex type
SSLMutex none
server config
This configures the SSL engine's semaphore (aka. lock) which is used for mutual
exclusion of operations which have to be done in a synchronized way between the
pre-forked Apache server processes. This directive can only be used in the
global server context because it's only useful to have one global mutex.
This directive is designed to closely match the
directive.
The following Mutex types are available:
This is the default where no Mutex is used at all. Use it at your own
risk. But because currently the Mutex is mainly used for synchronizing
write access to the SSL Session Cache you can live without it as long
as you accept a sometimes garbled Session Cache. So it's not recommended
to leave this the default. Instead configure a real Mutex.
This is an elegant Mutex variant where a Posix Semaphore is used when possible.
It is only available when the underlying platform
supports it.
This is a somewhat elegant Mutex variant where a SystemV IPC Semaphore is used when
possible. It is possible to "leak" SysV semaphores if processes crash before
the semaphore is removed. It is only available when the underlying platform
supports it.
This directive tells the SSL Module to pick the "best" semaphore implementation
available to it, choosing between Posix and SystemV IPC, in that order. It is only
available when the underlying platform and
supports at least one of the 2.
This directive tells the SSL Module to use Posix thread mutexes. It is only available
if the underlying platform and
supports it.
fcntl:/path/to/mutex
This is a portable Mutex variant where a physical (lock-)file and the fcntl()
function are used as the Mutex.
Always use a local disk filesystem for /path/to/mutex and never a file
residing on a NFS- or AFS-filesystem. It is only available when the underlying platform
supports it. Note: Internally, the Process ID (PID) of the
Apache parent process is automatically appended to
/path/to/mutex to make it unique, so you don't have to worry
about conflicts yourself. Notice that this type of mutex is not available
under the Win32 environment. There you have to use the semaphore
flock:/path/to/mutex
This is similar to the fcntl:/path/to/mutex method with the
exception that the flock() function is used to provide file
locking. It is only available when the underlying platform
supports it.
file:/path/to/mutex
This directive tells the SSL Module to pick the "best" file locking implementation
available to it, choosing between fcntl and flock,
in that order. It is only available when the underlying platform and
at least one of the 2.
default | yes
This directive tells the SSL Module to pick the default locking implementation
as determined by the platform and .
SSLMutex file:/usr/local/apache/logs/ssl_mutex
Configure various SSL engine run-time options
SSLOptions [+|-]option ...
server config, virtual host, directory, .htaccess
This directive can be used to control various run-time options on a
per-directory basis. Normally, if multiple SSLOptions
could apply to a directory, then the most specific one is taken
the options are not merged. However if all the
options on the SSLOptions directive are preceded by a
plus (+) or minus (-) symbol, the options
are merged. Any options preceded by a + are added to the
options currently in force, and any options preceded by a
- are removed from the options currently in force.
The available options are:
StdEnvVars
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.
ExportCertData
When this option is enabled, additional CGI/SSI environment variables are
created: SSL_SERVER_CERT, SSL_CLIENT_CERT and
SSL_CLIENT_CERT_CHAIN_n (with n = 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
FakeBasicAuth
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
openssl x509 command: openssl x509 -noout -subject -in
certificate.crt). Note that no password is
obtained from the user. Every entry in the user file needs this password:
``xxj31ZMTZzkVA'', which is the DES-encrypted version of the
word `password''. 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: ``$1$OXLyS...$Owx8s2/m9/gfkcRVXzgoE/''.
StrictRequire
This forces forbidden access when SSLRequireSSL or
SSLRequire successfully decided that access should be
forbidden. Usually the default is that in the case where a ``Satisfy
any'' directive is used, and other access restrictions are passed,
denial of access due to SSLRequireSSL or
SSLRequire is overridden (because that's how the Apache
Satisfy mechanism should work.) But for strict access restriction
you can use SSLRequireSSL and/or SSLRequire in
combination with an ``SSLOptions +StrictRequire''. Then an
additional ``Satisfy Any'' has no chance once mod_ssl has
decided to deny access.
OptRenegotiate
This enables optimized SSL connection renegotiation handling when SSL
directives are used in per-directory context. By default a strict
scheme is enabled where every per-directory reconfiguration of
SSL parameters causes a full SSL renegotiation handshake. When this
option is used mod_ssl tries to avoid unnecessary handshakes by doing more
granular (but still safe) parameter checks. Nevertheless these granular
checks sometimes maybe not what the user expects, so enable this on a
per-directory basis only, please.
SSLOptions +FakeBasicAuth -StrictRequire
&Files ~ "\.(cgi|shtml)$"&
SSLOptions +StdEnvVars -ExportCertData
Type of pass phrase dialog for encrypted private
SSLPassPhraseDialog type
SSLPassPhraseDialog builtin
server config
When Apache starts up it has to read the various Certificate (see
Private Key (see ) 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
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).
This scheme allows mod_ssl to be maximally flexible (because for N encrypted
Private Key files you can 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).
|/path/to/program [args...]
This mode allows an external program to be used which acts as a
pipe to a par the program is sent the standard
prompt text used for the builtin mode on
stdin, and is expected to write password strings on
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.
exec:/path/to/program
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 ``servername:portnumber'', the second is either
``RSA'', ``DSA'', or ``ECC''), which
indicate for which server and algorithm it has to print the corresponding
Pass Phrase to stdout.
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.
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 stdout.
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.
The reuse-algorithm above is used here, too. In other words: The external
program is called only once per unique Pass Phrase.
SSLPassPhraseDialog exec:/usr/local/apache/sbin/pp-filter
Configure usable SSL protocol flavors
SSLProtocol [+|-]protocol ...
SSLProtocol all
server config, virtual host
This directive can be used to control the SSL protocol flavors mod_ssl should
use when establishing its server environment. Clients then can only connect
with one of the provided protocols.
The available (case-insensitive) protocols are:
This is the Secure Sockets Layer (SSL) protocol, version 2.0. It is the
original SSL protocol as designed by Netscape Corporation.
Though its
use has been deprecated, because of weaknesses in the security of the protocol.
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.
This is the Transport Layer Security (TLS) protocol, version 1.0.
It is the successor to SSLv3 and is defined in
TLSv1.1 (when using OpenSSL 1.0.1 and later)
A revision of the TLS 1.0 protocol, as defined in
TLSv1.2 (when using OpenSSL 1.0.1 and later)
A revision of the TLS 1.1 protocol, as defined in
This is a shortcut for ``+SSLv2 +SSLv3 +TLSv1'' or
- when using OpenSSL 1.0.1 and later -
``+SSLv2 +SSLv3 +TLSv1 +TLSv1.1 +TLSv1.2'', respectively.
# enable SSLv3 and all available TLSv1 flavors, but not SSLv2
SSLProtocol All -SSLv2
File of concatenated PEM-encoded CA Certificates
for Remote Server Auth
SSLProxyCACertificateFile file-path
server config, virtual host
This directive sets the all-in-one file where you can assemble the
Certificates of Certification Authorities (CA) whose remote servers 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
SSLProxyCACertificateFile /usr/local/apache2/conf/ssl.crt/ca-bundle-remote-server.crt
Directory of PEM-encoded CA Certificates for
Remote Server Auth
SSLProxyCACertificatePath directory-path
server config, virtual host
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.
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
hash-value.N. And you should always make sure this directory
contains the appropriate symbolic links.
SSLProxyCACertificatePath /usr/local/apache2/conf/ssl.crt/
File of concatenated PEM-encoded CA CRLs for
Remote Server Auth
SSLProxyCARevocationFile file-path
server config, virtual host
This directive sets the all-in-one file where you can
assemble the Certificate Revocation Lists (CRL) of Certification
Authorities (CA) whose remote servers 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 .
SSLProxyCARevocationFile /usr/local/apache2/conf/ssl.crl/ca-bundle-remote-server.crl
Directory of PEM-encoded CA CRLs for
Remote Server Auth
SSLProxyCARevocationPath directory-path
server config, virtual host
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.
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
hash-value.rN. And you should always make sure this directory
contains the appropriate symbolic links.
SSLProxyCARevocationPath /usr/local/apache2/conf/ssl.crl/
Whether to check the remote server certificates CN field
SSLProxyCheckPeerCN on|off
SSLProxyCheckPeerCN off
server config, virtual host
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.
SSLProxyCheckPeerCN on
Whether to check if remote server certificate is expired
SSLProxyCheckPeerExpire on|off
SSLProxyCheckPeerExpire off
server config, virtual host
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
SSLProxyCheckPeerExpire on
Cipher Suite available for negotiation in SSL
proxy handshake
SSLProxyCipherSuite cipher-spec
SSLProxyCipherSuite ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP
server config, virtual host, directory, .htaccess
AuthConfig
Equivalent to SSLCipherSuite, but for the proxy connection.
Please refer to
for additional information.
SSL Proxy Engine Operation Switch
SSLProxyEngine on|off
SSLProxyEngine off
server config, virtual host
This directive toggles the usage of the SSL/TLS Protocol Engine for proxy. This
is usually used inside a
section to enable SSL/TLS for proxy
usage in a particular virtual host. By default the SSL/TLS Protocol Engine is
disabled for proxy both for the main server and all configured virtual hosts.
Note that the SSLProxyEngine directive should not, in
general, be included in a virtual host that will be acting as a
forward proxy (using &Proxy& or &ProxyRequest& directives.
SSLProxyEngine is not required to enable a forward proxy server to
proxy SSL/TLS requests.
&VirtualHost _default_:443&
SSLProxyEngine on
&/VirtualHost&
File of concatenated PEM-encoded CA certificates to be used by the proxy for choosing a certificate
SSLProxyMachineCertificateChainFile filename
server config
Not applicable
Available in Apache 2.2.23 and later
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.
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.
Security warning
If this directive is enabled, all of the certificates in the file will be
trusted as if they were also in .
SSLProxyMachineCertificateChainFile /usr/local/apache2/conf/ssl.crt/proxyCA.pem
File of concatenated PEM-encoded client certificates and keys to be used by the proxy
SSLProxyMachineCertificateFile filename
server config
Not applicable
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.
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 SSLProxyMachineCertificatePath.
Currently there is no support for encrypted private keys
SSLProxyMachineCertificateFile /usr/local/apache2/conf/ssl.crt/proxy.pem
Directory of PEM-encoded client certificates and keys to be used by the proxy
SSLProxyMachineCertificatePath directory
server config
Not applicable
This directive sets the directory where you keep the certificates and
keys used for authentication of the proxy server to remote servers.
The files in this directory must be PEM-encoded and are accessed through
hash filenames. Additionally, you must create symbolic links named
hash-value.N. And you should always make sure this
directory contains the appropriate symbolic links.
Currently there is no support for encrypted private keys
SSLProxyMachineCertificatePath /usr/local/apache2/conf/proxy.crt/
Configure usable SSL protocol flavors for proxy usage
SSLProxyProtocol [+|-]protocol ...
SSLProxyProtocol all
server config, virtual host
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.
Please refer to
for additional information.
Type of remote server Certificate verification
SSLProxyVerify level
SSLProxyVerify none
server config, virtual host
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.
Note that even when certificate verification is enabled,
does not check whether the
commonName (hostname) attribute of the server certificate
matches the hostname used to connect to the server.
In other words,
the proxy does not guarantee that the SSL connection to the backend
server is "secure" beyond the fact that the certificate is signed by
one of the CAs configured using the
SSLProxyCACertificatePath and/or
SSLProxyCACertificateFile directives.
In order to get this check done please have a look at
SSLProxyCheckPeerCN and
SSLProxyCheckPeerExpire directives which are off by
The following levels are available for level:
no remote server Certificate is required at all
the remote server may present a valid Certificate
the remote server has to present a valid Certificate
optional_no_ca:
the remote server may present a valid Certificate
but it need not to be (successfully) verifiable.
In practice only levels none and
require are really interesting, because level
optional doesn't work with all servers and level
optional_no_ca is actually against the idea of
authentication (but can be used to establish SSL test pages, etc.)
SSLProxyVerify require
Maximum depth of CA Certificates in Remote Server
Certificate verification
SSLProxyVerifyDepth number
SSLProxyVerifyDepth 1
server config, virtual host
AuthConfig
This directive sets how deeply mod_ssl should verify before deciding that the
remote server does not have a valid certificate.
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
SSLProxyVerifyDepth 10
Pseudo Random Number Generator (PRNG) seeding
SSLRandomSeed context source
server config
This configures one or more sources for seeding the Pseudo Random Number
Generator (PRNG) in OpenSSL at startup time (context is
startup) and/or just before a new SSL connection is established
(context is connect). This directive can only be used
in the global server context because the PRNG is a global facility.
The following source variants are available:
This is the always available builtin seeding source. Its 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.
file:/path/to/source
This variant uses an external file /path/to/source as the
source for seeding the PRNG. When bytes is specified, only the
first bytes number of bytes of the file form the entropy (and
bytes is given to /path/to/source as the first
argument). When bytes is not specified the whole file forms the
entropy (and 0 is given to /path/to/source as
the first argument). Use this especially at startup time, for instance
with an available /dev/random and/or
/dev/urandom devices (which usually exist on modern Unix
derivatives like FreeBSD and Linux).
But be careful: Usually /dev/random 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 /dev/urandom 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.
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 rndcontrol(8) on those platforms. Alternatively, when
your system lacks such a random device, you can use a tool
(Entropy Gathering Daemon) and run its client program with the
exec:/path/to/program/ variant (see below) or use
egd:/path/to/egd-socket (see below).
exec:/path/to/program
This variant uses an external executable
/path/to/program as the source for seeding the
PRNG. When bytes is specified, only the first
bytes number of bytes of its stdout contents
form the entropy. When bytes is not specified, the
entirety of the data produced on stdout 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 truerand utility you can
find in the mod_ssl distribution which is based on the AT&T
truerand 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.
egd:/path/to/egd-socket (Unix only)
This variant uses the Unix domain socket of the
external Entropy Gathering Daemon (EGD) (see ) to seed the PRNG. Use this if no random device exists
on your platform.
SSLRandomSeed startup builtin
SSLRandomSeed startup file:/dev/random
SSLRandomSeed startup file:/dev/urandom 1024
SSLRandomSeed startup exec:/usr/local/bin/truerand 16
SSLRandomSeed connect builtin
SSLRandomSeed connect file:/dev/random
SSLRandomSeed connect file:/dev/urandom 1024
Set the size for the SSL renegotiation buffer
SSLRenegBufferSize bytes
SSLRenegBufferSize 131072
directory, .htaccess
AuthConfig
If an SSL renegotiation is required in per-location context, for
example, any use of
in a Directory or
Location block, then
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.
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.
SSLRenegBufferSize 262144
Allow access only when an arbitrarily complex
boolean expression is true
SSLRequire expression
directory, .htaccess
AuthConfig
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.
The implementation of SSLRequire is not thread safe.
Using SSLRequire inside .htaccess files
on a threaded
may cause random crashes.
The expression must match the following syntax (given as a BNF
grammar notation):
::= "true" | "false"
| "!" expr
| expr "&&" expr
| expr "||" expr
| "(" expr ")"
::= word "==" word | word "eq" word
| word "!=" word | word "ne" word
| word "&"
word | word "lt" word
| word "&=" word | word "le" word
| word "&"
word | word "gt" word
| word "&=" word | word "ge" word
| word "in" "{" wordlist "}"
| word "in" "OID(" word ")"
| word "=~" regex
| word "!~" regex
wordlist ::= word
| wordlist "," word
| variable
| function
::= [0-9]+
variable ::= "%{" varname "}"
function ::= funcname "(" funcargs ")"
while for varname any variable from
can be used. Finally for
funcname the following functions are available:
file(filename)
This function takes one string argument and expands to the contents of the
file. This is especially useful for matching this contents against a
regular expression, etc.
Notice that expression is first parsed into an internal machine
representation and then evaluated in a second step. Actually, in Global and
Per-Server Class context expression is parsed at startup time and
at runtime only the machine representation is executed. For Per-Directory
context, specifically in a .htaccess context, this is different: here
expression has to be parsed and immediately executed for every request.
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} &= 1 and %{TIME_WDAY} &= 5 \
and %{TIME_HOUR} &= 8 and %{TIME_HOUR} &= 20
or %{REMOTE_ADDR} =~ m/^192\.76\.162\.[0-9]+$/
The OID() function expects to find zero or more instances
of the given OID in the client certificate, and compares the left-hand side
string against the value of matching OID attributes. Every matching OID is
checked, until a match is found.
Standard CGI/1.0 and Apache variables:
HTTP_USER_AGENT
HTTP_REFERER
QUERY_STRING
SERVER_SOFTWARE
HTTP_COOKIE
REMOTE_HOST
API_VERSION
HTTP_FORWARDED
REMOTE_IDENT
HTTP_PROXY_CONNECTION
DOCUMENT_ROOT
HTTP_ACCEPT
SERVER_ADMIN
HTTP:headername
SERVER_NAME
THE_REQUEST
SERVER_PORT
REQUEST_METHOD
SERVER_PROTOCOL
REQUEST_SCHEME
REMOTE_ADDR
REQUEST_URI
REMOTE_USER
ENV:variablename
REQUEST_FILENAME
SSL-related variables:
SSL_CLIENT_M_VERSION
SSL_SERVER_M_VERSION
SSL_CLIENT_M_SERIAL
SSL_SERVER_M_SERIAL
SSL_PROTOCOL
SSL_CLIENT_V_START
SSL_SERVER_V_START
SSL_SESSION_ID
SSL_CLIENT_V_END
SSL_SERVER_V_END
SSL_CIPHER
SSL_CLIENT_S_DN
SSL_SERVER_S_DN
SSL_CIPHER_EXPORT
SSL_CLIENT_S_DN_C
SSL_SERVER_S_DN_C
SSL_CIPHER_ALGKEYSIZE
SSL_CLIENT_S_DN_ST
SSL_SERVER_S_DN_ST
SSL_CIPHER_USEKEYSIZE
SSL_CLIENT_S_DN_L
SSL_SERVER_S_DN_L
SSL_VERSION_LIBRARY
SSL_CLIENT_S_DN_O
SSL_SERVER_S_DN_O
SSL_VERSION_INTERFACE
SSL_CLIENT_S_DN_OU
SSL_SERVER_S_DN_OU
SSL_CLIENT_S_DN_CN
SSL_SERVER_S_DN_CN
SSL_CLIENT_S_DN_T
SSL_SERVER_S_DN_T
SSL_CLIENT_S_DN_I
SSL_SERVER_S_DN_I
SSL_CLIENT_S_DN_G
SSL_SERVER_S_DN_G
SSL_CLIENT_S_DN_S
SSL_SERVER_S_DN_S
SSL_CLIENT_S_DN_D
SSL_SERVER_S_DN_D
SSL_CLIENT_S_DN_UID
SSL_SERVER_S_DN_UID
SSL_CLIENT_S_DN_Email
SSL_SERVER_S_DN_Email
SSL_CLIENT_I_DN
SSL_SERVER_I_DN
SSL_CLIENT_I_DN_C
SSL_SERVER_I_DN_C
SSL_CLIENT_I_DN_ST
SSL_SERVER_I_DN_ST
SSL_CLIENT_I_DN_L
SSL_SERVER_I_DN_L
SSL_CLIENT_I_DN_O
SSL_SERVER_I_DN_O
SSL_CLIENT_I_DN_OU
SSL_SERVER_I_DN_OU
SSL_CLIENT_I_DN_CN
SSL_SERVER_I_DN_CN
SSL_CLIENT_I_DN_T
SSL_SERVER_I_DN_T
SSL_CLIENT_I_DN_I
SSL_SERVER_I_DN_I
SSL_CLIENT_I_DN_G
SSL_SERVER_I_DN_G
SSL_CLIENT_I_DN_S
SSL_SERVER_I_DN_S
SSL_CLIENT_I_DN_D
SSL_SERVER_I_DN_D
SSL_CLIENT_I_DN_UID
SSL_SERVER_I_DN_UID
SSL_CLIENT_I_DN_Email
SSL_SERVER_I_DN_Email
SSL_CLIENT_A_SIG
SSL_SERVER_A_SIG
SSL_CLIENT_A_KEY
SSL_SERVER_A_KEY
SSL_CLIENT_CERT
SSL_SERVER_CERT
SSL_CLIENT_CERT_CHAIN_n
SSL_CLIENT_VERIFY
SSL_TLS_SNI
Deny access when SSL is not used for the
HTTP request
SSLRequireSSL
directory, .htaccess
AuthConfig
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.
SSLRequireSSL
Type of the global/inter-process SSL Session
SSLSessionCache type
SSLSessionCache none
server config
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
different pre-forked server processes. Here an inter-process cache
helps to avoid unnecessary session handshakes.
The following four storage types are currently supported:
This disables the global/inter-process Session Cache.
will incur a noticeable speed penalty and may cause problems if
using certain browsers, particularly if client certificates are
This setting is not recommended.
nonenotnull
This disables any global/inter-process Session Cache.
it does force OpenSSL to send a non-null session ID to
accommodate buggy clients that require one.
dbm:/path/to/datafile
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.
shm:/path/to/datafile[(size)]
This makes use of a high-performance cyclic buffer
(approx. size bytes in size) inside a shared memory
segment in RAM (established via /path/to/datafile) to
synchronize the local OpenSSL memory caches of the server
processes.
This is the recommended session cache.
dc:UNIX:/path/to/socket
This makes use of the
distributed session
caching libraries.
The argument should specify the location of
the server or proxy to be used using the dist
for example, UNIX:/path/to/socket specifies a UNIX
domain socket (typically a local dc_client proxy);
IP::9001 specifies an IP
SSLSessionCache dbm:/usr/local/apache/logs/ssl_gcache_data
SSLSessionCache shm:/usr/local/apache/logs/ssl_gcache_data(512000)
Number of seconds before an SSL session expires
in the Session Cache
SSLSessionCacheTimeout seconds
SSLSessionCacheTimeout 300
server config, virtual host
Applies also to RFC 5077 TLS session resumption in Apache 2.2.28 and later
This directive sets the timeout in seconds for the information stored in the
global/inter-process SSL Session Cache, the OpenSSL internal memory cache and
for sessions resumed by TLS session resumption (RFC 5077).
It can be set as low as 15 for testing, but should be set to higher
values like 300 in real life.
SSLSessionCacheTimeout 600
Persistent encryption/decryption key for TLS session tickets
SSLSessionTicketKeyFile file-path
server config, virtual host
Available in httpd 2.2.30 and later, if using OpenSSL 0.9.8h or later
Optionally configures a secret key for encrypting and decrypting
TLS session tickets, as defined in
Primarily suitable for clustered environments where TLS sessions information
should be shared between multiple nodes. For single-instance httpd setups,
it is recommended to not configure a ticket key file, but to
rely on (random) keys generated by mod_ssl at startup, instead.
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:
dd if=/dev/random of=/path/to/file.tkey bs=1 count=48
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.
A new ticket key only gets used after restarting the web server.
All existing session tickets become invalid after a restart.
The ticket key file contains sensitive keying material and should
be protected with file permissions similar to those used for
Enable or disable use of TLS session tickets
SSLSessionTickets on|off
SSLSessionTickets on
server config, virtual host
Available in httpd 2.2.30 and later, if using OpenSSL 0.9.8f
This directive allows to enable or disable the use of TLS session tickets
(RFC 5077).
TLS session tickets are enabled by default. Using them without restarting
the web server with an appropriate frequency (e.g. daily) compromises perfect
forward secrecy.
Whether to allow non SNI clients to access a name based virtual
SSLStrictSNIVHostCheck on|off
SSLStrictSNIVHostCheck off
server config, virtual host
Available in Apache 2.2.12 and later
This directive sets whether a non SNI client is allowed to access a name based
virtual host. If set to on in the non default name based virtual
host, non SNI clients are not allowed to access this particular virtual host.
If set to on in the default name based virtual host, non SNI
clients are not allowed to access any name based virtual host belonging to
this IP / port combination.
This option is only available if httpd was compiled against an SNI capable
version of OpenSSL.
SSLStrictSNIVHostCheck on
Variable name to determine user name
SSLUserName varname
server config, directory, .htaccess
AuthConfig
Available in Apache 2.0.51 and later
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
REMOTE_USER to be set.
The varname can be
any of the .
Note that this directive has no effect if the
FakeBasicAuth option is used (see ).
SSLUserName SSL_CLIENT_S_DN_CN
Type of Client Certificate verification
SSLVerifyClient level
SSLVerifyClient none
server config, virtual host, directory, .htaccess
AuthConfig
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.
The following levels are available for level:
no client Certificate is required at all
the client may present a valid Certificate
the client has to present a valid Certificate
optional_no_ca:
the client may present a valid Certificate
but it need not to be (successfully) verifiable.
In practice only levels none and
require are really interesting, because level
optional doesn't work with all browsers and level
optional_no_ca is actually against the idea of
authentication (but can be used to establish SSL test pages, etc.)
SSLVerifyClient require
Maximum depth of CA Certificates in Client
Certificate verification
SSLVerifyDepth number
SSLVerifyDepth 1
server config, virtual host, directory, .htaccess
AuthConfig
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.
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
SSLVerifyDepth 10
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