Apache Module mod_ssl

Available Languages: en | + fr

+ + + +

Description:	Strong cryptography using the Secure Sockets +Layer (SSL) and Transport Layer Security (TLS) protocols
Status:	Extension
Module Identifier:	ssl_module
Source File:	mod_ssl.c

Summary

+ +

This module provides SSL v3 and TLS v1.x support for the Apache +HTTP Server. SSL v2 is no longer supported.

+ +

This module relies on OpenSSL +to provide the cryptography engine.

+ +

Further details, discussion, and examples are provided in the +SSL documentation.

Topics

Environment Variables
Custom Log Formats
Request Notes
Expression Parser Extension
Authorization providers for use with Require

Directives

SSLCACertificateFile
SSLCACertificatePath
SSLCADNRequestFile
SSLCADNRequestPath
SSLCARevocationCheck
SSLCARevocationFile
SSLCARevocationPath
SSLCertificateChainFile
SSLCertificateFile
SSLCertificateKeyFile
SSLCipherSuite
SSLCompression
SSLCryptoDevice
SSLEngine
SSLFIPS
SSLHonorCipherOrder
SSLInsecureRenegotiation
SSLOCSPDefaultResponder
SSLOCSPEnable
SSLOCSPNoverify
SSLOCSPOverrideResponder
SSLOCSPProxyURL
SSLOCSPResponderCertificateFile
SSLOCSPResponderTimeout
SSLOCSPResponseMaxAge
SSLOCSPResponseTimeSkew
SSLOCSPUseRequestNonce
SSLOpenSSLConfCmd
SSLOptions
SSLPassPhraseDialog
SSLProtocol
SSLProxyCACertificateFile
SSLProxyCACertificatePath
SSLProxyCARevocationCheck
SSLProxyCARevocationFile
SSLProxyCARevocationPath
SSLProxyCheckPeerCN
SSLProxyCheckPeerExpire
SSLProxyCheckPeerName
SSLProxyCipherSuite
SSLProxyEngine
SSLProxyMachineCertificateChainFile
SSLProxyMachineCertificateFile
SSLProxyMachineCertificatePath
SSLProxyProtocol
SSLProxyVerify
SSLProxyVerifyDepth
SSLRandomSeed
SSLRenegBufferSize
SSLRequire
SSLRequireSSL
SSLSessionCache
SSLSessionCacheTimeout
SSLSessionTicketKeyFile
SSLSessionTickets
SSLSRPUnknownUserSeed
SSLSRPVerifierFile
SSLStaplingCache
SSLStaplingErrorCacheTimeout
SSLStaplingFakeTryLater
SSLStaplingForceURL
SSLStaplingResponderTimeout
SSLStaplingResponseMaxAge
SSLStaplingResponseTimeSkew
SSLStaplingReturnResponderErrors
SSLStaplingStandardCacheTimeout
SSLStrictSNIVHostCheck
SSLUserName
SSLUseStapling
SSLVerifyClient
SSLVerifyDepth

Bugfix checklist

Environment Variables

+ +

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 Compatibility chapter for details on the +compatibility variables.

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

Variable Name:	Value Type:	Description:
`HTTPS`	flag	HTTPS is being used.
`SSL_PROTOCOL`	string	The SSL protocol version (SSLv3, TLSv1, TLSv1.1, TLSv1.2)
`SSL_SESSION_ID`	string	The hex-encoded SSL session id
`SSL_SESSION_RESUMED`	string	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
`SSL_SECURE_RENEG`	string	`true` if secure renegotiation is supported, else `false`
`SSL_CIPHER`	string	The cipher specification name
`SSL_CIPHER_EXPORT`	string	`true` if cipher is an export cipher
`SSL_CIPHER_USEKEYSIZE`	number	Number of cipher bits (actually used)
`SSL_CIPHER_ALGKEYSIZE`	number	Number of cipher bits (possible)
`SSL_COMPRESS_METHOD`	string	SSL compression method negotiated
`SSL_VERSION_INTERFACE`	string	The mod_ssl program version
`SSL_VERSION_LIBRARY`	string	The OpenSSL program version
`SSL_CLIENT_M_VERSION`	string	The version of the client certificate
`SSL_CLIENT_M_SERIAL`	string	The serial of the client certificate
`SSL_CLIENT_S_DN`	string	Subject DN in client's certificate
`SSL_CLIENT_S_DN_`x509	string	Component of client's Subject DN
`SSL_CLIENT_SAN_Email_`n	string	Client certificate's subjectAltName extension entries of type rfc822Name
`SSL_CLIENT_SAN_DNS_`n	string	Client certificate's subjectAltName extension entries of type dNSName
`SSL_CLIENT_SAN_OTHER_msUPN_`n	string	Client certificate's subjectAltName extension entries of type otherName, Microsoft User Principal Name form (OID 1.3.6.1.4.1.311.20.2.3)
`SSL_CLIENT_I_DN`	string	Issuer DN of client's certificate
`SSL_CLIENT_I_DN_`x509	string	Component of client's Issuer DN
`SSL_CLIENT_V_START`	string	Validity of client's certificate (start time)
`SSL_CLIENT_V_END`	string	Validity of client's certificate (end time)
`SSL_CLIENT_V_REMAIN`	string	Number of days until client's certificate expires
`SSL_CLIENT_A_SIG`	string	Algorithm used for the signature of client's certificate
`SSL_CLIENT_A_KEY`	string	Algorithm used for the public key of client's certificate
`SSL_CLIENT_CERT`	string	PEM-encoded client certificate
`SSL_CLIENT_CERT_CHAIN_`n	string	PEM-encoded certificates in client certificate chain
`SSL_CLIENT_CERT_RFC4523_CEA`	string	Serial number and issuer of the certificate. The format matches that of the CertificateExactAssertion in RFC4523
`SSL_CLIENT_VERIFY`	string	`NONE`, `SUCCESS`, `GENEROUS` or `FAILED:`reason
`SSL_SERVER_M_VERSION`	string	The version of the server certificate
`SSL_SERVER_M_SERIAL`	string	The serial of the server certificate
`SSL_SERVER_S_DN`	string	Subject DN in server's certificate
`SSL_SERVER_SAN_Email_`n	string	Server certificate's subjectAltName extension entries of type rfc822Name
`SSL_SERVER_SAN_DNS_`n	string	Server certificate's subjectAltName extension entries of type dNSName
`SSL_SERVER_SAN_OTHER_dnsSRV_`n	string	Server certificate's subjectAltName extension entries of type otherName, SRVName form (OID 1.3.6.1.5.5.7.8.7, RFC 4985)
`SSL_SERVER_S_DN_`x509	string	Component of server's Subject DN
`SSL_SERVER_I_DN`	string	Issuer DN of server's certificate
`SSL_SERVER_I_DN_`x509	string	Component of server's Issuer DN
`SSL_SERVER_V_START`	string	Validity of server's certificate (start time)
`SSL_SERVER_V_END`	string	Validity of server's certificate (end time)
`SSL_SERVER_A_SIG`	string	Algorithm used for the signature of server's certificate
`SSL_SERVER_A_KEY`	string	Algorithm used for the public key of server's certificate
`SSL_SERVER_CERT`	string	PEM-encoded server certificate
`SSL_SRP_USER`	string	SRP username
`SSL_SRP_USERINFO`	string	SRP user info
`SSL_TLS_SNI`	string	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 httpd 2.2.0 and +later, x509 may also include a numeric _n +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, SSL_SERVER_S_DN_OU_0 +and +SSL_SERVER_S_DN_OU_1 could be used to reference each. A +variable name without a _n suffix is equivalent to that +name with a _0 suffix; the first (or only) attribute. +When the environment table is populated using +the StdEnvVars option of +the SSLOptions directive, the +first (or only) attribute of any DN is added only under a non-suffixed +name; i.e. no _0 suffixed entries are added.

+ +

In httpd 2.4.32 and later, an optional _RAW suffix may be +added to x509 in a DN component, to suppress conversion of +the attribute value to UTF-8. This must be placed after the index +suffix (if any). For example, SSL_SERVER_S_DN_OU_RAW or +SSL_SERVER_S_DN_OU_0_RAW could be used.

+ +

The format of the *_DN variables has changed in Apache HTTPD +2.3.11. See the LegacyDNStringFormat option for +SSLOptions for details.

+ +

SSL_CLIENT_V_REMAIN is only available in version 2.1 +and later.

+ +

A number of additional environment variables can also be used +in SSLRequire expressions, or in custom log +formats:

+ +

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

+ +

In these contexts, two special formats can also be used:

+ +

ENV:variablename: This will expand to the standard environment + variable variablename.
HTTP:headername: This will expand to the value of the request header with name + headername.

+ +

Custom Log Formats

+ +

When mod_ssl is built into Apache or at least +loaded (under DSO situation) additional functions exist for the Custom Log Format of +mod_log_config. 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 Compatibility chapter.

Example

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 SSLOptions +directive.

Request Notes

+ +

mod_ssl sets "notes" for the request which can be +used in logging with the %{name}n format +string in mod_log_config.

+ +

The notes supported are as follows:

+ +

ssl-access-forbidden: This note is set to the value 1 if access was + denied due to an SSLRequire + or SSLRequireSSL directive.
ssl-secure-reneg: If mod_ssl is built against a version of + OpenSSL which supports the secure renegotiation extension, this note + is set to the value 1 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 0. + If mod_ssl 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.

+ +

Expression Parser Extension

+ +

When mod_ssl is built into Apache or at least +loaded (under DSO situation) any variables +provided by mod_ssl can be used in expressions +for the ap_expr Expression Parser. +The variables can be referenced using the syntax +``%{varname}''. Starting +with version 2.4.18 one can also use the +mod_rewrite style syntax +``%{SSL:varname}'' or +the function style syntax +``ssl(varname)''.

Example (using `mod_headers`)

Header set X-SSL-PROTOCOL "expr=%{SSL_PROTOCOL}"
+Header set X-SSL-CIPHER "expr=%{SSL:SSL_CIPHER}"

This feature even works without setting the StdEnvVars +option of the SSLOptions +directive.

Authorization providers for use with Require

+ +

mod_ssl provides a few authentication providers for use + with mod_authz_core's + Require directive.

+ +

Require ssl

+ +

The ssl provider denies access if a connection is not + encrypted with SSL. This is similar to the + SSLRequireSSL directive.

+ +

Require ssl

+ + + + +

Require ssl-verify-client

+ +

The ssl provider allows access if the user is + authenticated with a valid client certificate. This is only + useful if SSLVerifyClient optional is in effect.

+ +

The following example grants access if the user is authenticated + either with a client certificate or by username and password.

+ +

Require ssl-verify-client
+Require valid-user

+ + + + +

SSLCACertificateFile Directive

+ + + + + + +

Description:	File of concatenated PEM-encoded CA Certificates +for Client Auth
Syntax:	`SSLCACertificateFile file-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+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 +SSLCACertificatePath.

Example

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

+ +

SSLCACertificatePath Directive

+ + + + + + +

Description:	Directory of PEM-encoded CA Certificates for +Client Auth
Syntax:	`SSLCACertificatePath directory-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+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.

Example

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

+ +

SSLCADNRequestFile Directive

+ + + + + + +

Description:	File of concatenated PEM-encoded CA Certificates +for defining acceptable CA names
Syntax:	`SSLCADNRequestFile file-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

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 SSLCADNRequestPath or SSLCADNRequestFile are given, then the +set of acceptable CA names sent to the client is the names of all the +CA certificates given by the SSLCACertificateFile and SSLCACertificatePath directives; in other +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, SSLCADNRequestPath and/or SSLCADNRequestFile 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.

+ +

SSLCADNRequestFile must +specify an all-in-one file containing a concatenation of +PEM-encoded CA certificates.

+ +

Example

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

+ +

SSLCADNRequestPath Directive

+ + + + + + +

Description:	Directory of PEM-encoded CA Certificates for +defining acceptable CA names
Syntax:	`SSLCADNRequestPath directory-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+ +

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. See the SSLCADNRequestFile directive for more +details.

+ +

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.

Example

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

+ +

SSLCARevocationCheck Directive

+ + + + + + + + +

Description:	Enable CRL-based revocation checking
Syntax:	`SSLCARevocationCheck chain\|leaf\|none flags`
Default:	`SSLCARevocationCheck none`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Optional flags available in httpd 2.4.21 or +later

+Enables certificate revocation list (CRL) checking. At least one of +SSLCARevocationFile +or SSLCARevocationPath must be +configured. When set to chain (recommended setting), +CRL checks are applied to all certificates in the chain, while setting it to +leaf limits the checks to the end-entity cert. +

The available flags are:

no_crl_for_cert_ok +
+ Prior to version 2.3.15, CRL checking in mod_ssl also succeeded when + no CRL(s) for the checked certificate(s) were found in any of the locations + configured with SSLCARevocationFile + or SSLCARevocationPath. +
+
+ With the introduction of SSLCARevocationFile, + the behavior has been changed: by default with chain or + leaf, CRLs must be present for the + validation to succeed - otherwise it will fail with an + "unable to get certificate CRL" error. +
+
+ The flag no_crl_for_cert_ok allows to restore + previous behaviour. +
+

Example

SSLCARevocationCheck chain

Compatibility with versions 2.2

SSLCARevocationCheck chain no_crl_for_cert_ok

+ +

SSLCARevocationFile Directive

+ + + + + + +

Description:	File of concatenated PEM-encoded CA CRLs for +Client Auth
Syntax:	`SSLCARevocationFile file-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+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 SSLCARevocationPath.

Example

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

+ +

SSLCARevocationPath Directive

+ + + + + + +

Description:	Directory of PEM-encoded CA CRLs for +Client Auth
Syntax:	`SSLCARevocationPath directory-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+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.

Example

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

+ +

SSLCertificateChainFile Directive

+ + + + + + +

Description:	File of PEM-encoded Server CA Certificates
Syntax:	`SSLCertificateChainFile file-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

SSLCertificateChainFile is deprecated

SSLCertificateChainFile became obsolete with version 2.4.8, +when SSLCertificateFile +was extended to also load intermediate CA certificates from the server +certificate file.

+ +

+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 SSLCACertificatePath 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 SSLCACertificatePath 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.

Example

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

+ +

SSLCertificateFile Directive

+ + + + + + +

Description:	Server PEM-encoded X.509 certificate data file
Syntax:	`SSLCertificateFile file-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+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 multiple times (referencing different filenames) +to support multiple algorithms for server authentication - typically +RSA, DSA, and ECC. The number of supported algorithms depends on the +OpenSSL version being used for mod_ssl: with version 1.0.0 or later, +openssl list-public-key-algorithms will output a list +of supported algorithms, see also the note below about limitations +of OpenSSL versions prior to 1.0.2 and the ways to work around them. +

+ +

+The files may also include intermediate CA certificates, sorted from +leaf to root. This is supported with version 2.4.8 and later, +and obsoletes SSLCertificateChainFile. +When running with OpenSSL 1.0.2 or later, this allows +to configure the intermediate CA chain on a per-certificate basis. +

+ +

+Custom DH parameters and an EC curve name for ephemeral keys, +can also be added to end of the first file configured using +SSLCertificateFile. +This is supported in version 2.4.7 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 end-entity certificate's private key can also be +added to the certificate file instead of using a separate +SSLCertificateKeyFile +directive. This practice is highly discouraged. If it is used, +the certificate files using such an embedded key must be configured +after the certificates using a separate key file. 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 2.4.7, mod_ssl makes use of +standardized DH parameters with prime lengths of 2048, 3072 and 4096 bits +and with additional prime lengths of 6144 and 8192 bits beginning with +version 2.4.10 +(from RFC 3526), and hands +them out to clients based on the length of the certificate's RSA/DSA key. +With Java-based clients in particular (Java 7 or earlier), this may lead +to handshake failures - see this +FAQ answer for working around +such issues. +

+ +

Default DH parameters when using multiple certificates and OpenSSL +versions prior to 1.0.2

+When using multiple certificates to support different authentication algorithms +(like RSA, DSA, but mainly ECC) and OpenSSL prior to 1.0.2, it is recommended +to either use custom DH parameters (preferably) by adding them to the +first certificate file (as described above), or to order the +SSLCertificateFile directives such that RSA/DSA +certificates are placed after the ECC one. +

+This is due to a limitation in older versions of OpenSSL which don't let the +Apache HTTP Server determine the currently selected certificate at handshake +time (when the DH parameters must be sent to the peer) but instead always +provide the last configured certificate. Consequently, the server may select +default DH parameters based on the length of the wrong certificate's key (ECC +keys are much smaller than RSA/DSA ones and their length is not relevant for +selecting DH primes). +

+Since custom DH parameters always take precedence over the default ones, this +issue can be avoided by creating and configuring them (as described above), +thus using a custom/suitable length. +

+ +

Example

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

+ +

SSLCertificateKeyFile Directive

+ + + + + + +

Description:	Server PEM-encoded private key file
Syntax:	`SSLCertificateKeyFile file-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+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 multiple times (referencing different filenames) +to support multiple algorithms for server authentication. For each +SSLCertificateKeyFile +directive, there must be a matching SSLCertificateFile +directive.

+ +

+The private key may also be combined with the certificate in the file given by +SSLCertificateFile, but this practice +is highly discouraged. If it is used, the certificate files using such +an embedded key must be configured after the certificates using a separate +key file.

+ +

Example

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

+ +

SSLCipherSuite Directive

+ + + + + + + + +

Description:	Cipher Suite available for negotiation in SSL +handshake
Syntax:	`SSLCipherSuite [protocol] cipher-spec`
Default:	`SSLCipherSuite DEFAULT (depends on OpenSSL version)`
Context:	server config, virtual host, directory, .htaccess
Override:	AuthConfig
Status:	Extension
Module:	mod_ssl

+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. The optional +protocol specifier can configure the Cipher Suite for a specific SSL version. +Possible values include "SSL" for all SSL Protocols up to and including TLSv1.2. +

+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.

+If the SSL library supports TLSv1.3 (OpenSSL 1.1.1 and later), the protocol +specifier "TLSv1.3" can be used to configure the cipher suites for that protocol. +Since TLSv1.3 does not offer renegotiations, specifying ciphers for it in +a directory context is not allowed.

+For a list of TLSv1.3 cipher names, see +the OpenSSL +documentation.

+An SSL cipher specification in cipher-spec is composed of 4 major +attributes plus a few extra minor ones:

Key Exchange Algorithm:
+ RSA, Diffie-Hellman, Elliptic Curve Diffie-Hellman, Secure Remote Password +
Authentication Algorithm:
+ RSA, Diffie-Hellman, DSS, ECDSA, or none. +
Cipher/Encryption Algorithm:
+ AES, DES, Triple-DES, RC4, RC2, IDEA, etc. +
MAC Digest Algorithm:
+ MD5, SHA or SHA1, SHA256, SHA384. +

An SSL cipher can also be an export cipher. SSLv2 ciphers are no longer +supported. 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 Table +1). The actually available ciphers and aliases depends on the used +openssl version. Newer openssl versions may include additional ciphers.

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

Tag	Description
Key Exchange Algorithm:
`kRSA`	RSA key exchange
`kDHr`	Diffie-Hellman key exchange with RSA key
`kDHd`	Diffie-Hellman key exchange with DSA key
`kEDH`	Ephemeral (temp.key) Diffie-Hellman key exchange (no cert)
`kSRP`	Secure Remote Password (SRP) key exchange
Authentication Algorithm:
`aNULL`	No authentication
`aRSA`	RSA authentication
`aDSS`	DSS authentication
`aDH`	Diffie-Hellman authentication
Cipher Encoding Algorithm:
`eNULL`	No encryption
`NULL`	alias for eNULL
`AES`	AES encryption
`DES`	DES encryption
`3DES`	Triple-DES encryption
`RC4`	RC4 encryption
`RC2`	RC2 encryption
`IDEA`	IDEA encryption
MAC Digest Algorithm:
`MD5`	MD5 hash function
`SHA1`	SHA1 hash function
`SHA`	alias for SHA1
`SHA256`	SHA256 hash function
`SHA384`	SHA384 hash function
Aliases:
`SSLv3`	all SSL version 3.0 ciphers
`TLSv1`	all TLS version 1.0 ciphers
`EXP`	all export ciphers
`EXPORT40`	all 40-bit export ciphers only
`EXPORT56`	all 56-bit export ciphers only
`LOW`	all low strength ciphers (no export, single DES)
`MEDIUM`	all ciphers with 128 bit encryption
`HIGH`	all ciphers using Triple-DES
`RSA`	all ciphers using RSA key exchange
`DH`	all ciphers using Diffie-Hellman key exchange
`EDH`	all ciphers using Ephemeral Diffie-Hellman key exchange
`ECDH`	Elliptic Curve Diffie-Hellman key exchange
`ADH`	all ciphers using Anonymous Diffie-Hellman key exchange
`AECDH`	all ciphers using Anonymous Elliptic Curve Diffie-Hellman key exchange
`SRP`	all ciphers using Secure Remote Password (SRP) key exchange
`DSS`	all ciphers using DSS authentication
`ECDSA`	all ciphers using ECDSA authentication
`aNULL`	all ciphers using no authentication

+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 (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 2.4.7, null and export-grade +ciphers are always disabled, as mod_ssl unconditionally adds +!aNULL:!eNULL:!EXP to any cipher string 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 +depends on the version of the OpenSSL libraries used. Let's suppose it is +``RC4-SHA:AES128-SHA:HIGH:MEDIUM:!aNULL:!MD5'' which +means the following: Put RC4-SHA and AES128-SHA at +the beginning. We do this, because these ciphers offer a good compromise +between speed and security. Next, include high and medium security ciphers. +Finally, remove all ciphers which do not authenticate, i.e. for SSL the +Anonymous Diffie-Hellman ciphers, as well as all ciphers which use +MD5 as hash algorithm, because it has been proven insufficient.

$ openssl ciphers -v 'RC4-SHA:AES128-SHA:HIGH:MEDIUM:!aNULL:!MD5'
+RC4-SHA                 SSLv3 Kx=RSA      Au=RSA  Enc=RC4(128)  Mac=SHA1
+AES128-SHA              SSLv3 Kx=RSA      Au=RSA  Enc=AES(128)  Mac=SHA1
+DHE-RSA-AES256-SHA      SSLv3 Kx=DH       Au=RSA  Enc=AES(256)  Mac=SHA1
+...                     ...               ...     ...           ...
+SEED-SHA                SSLv3 Kx=RSA      Au=RSA  Enc=SEED(128) Mac=SHA1
+PSK-RC4-SHA             SSLv3 Kx=PSK      Au=PSK  Enc=RC4(128)  Mac=SHA1
+KRB5-RC4-SHA            SSLv3 Kx=KRB5     Au=KRB5 Enc=RC4(128)  Mac=SHA1

The complete list of particular RSA & DH ciphers for SSL is given in Table 2.

Example

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

+ + + + + + + + + + + + + + + + + + + + + + + + + + +

Cipher-Tag	Protocol	Key Ex.	Auth.	Enc.	MAC	Type
RSA Ciphers:
`DES-CBC3-SHA`	SSLv3	RSA	RSA	3DES(168)	SHA1
`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
`DES-CBC-SHA`	SSLv3	RSA	RSA	DES(56)	SHA1
`EXP-DES-CBC-SHA`	SSLv3	RSA(512)	RSA	DES(40)	SHA1	export
`EXP-RC2-CBC-MD5`	SSLv3	RSA(512)	RSA	RC2(40)	MD5	export
`EXP-RC4-MD5`	SSLv3	RSA(512)	RSA	RC4(40)	MD5	export
`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	export
`EXP-EDH-DSS-DES-CBC-SHA`	SSLv3	DH(512)	DSS	DES(40)	SHA1	export
`EXP-ADH-DES-CBC-SHA`	SSLv3	DH(512)	None	DES(40)	SHA1	export
`EXP-ADH-RC4-MD5`	SSLv3	DH(512)	None	RC4(40)	MD5	export

+ +

SSLCompression Directive

+ + + + + + + + +

Description:	Enable compression on the SSL level
Syntax:	`SSLCompression on\|off`
Default:	`SSLCompression off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.3 and later, if using OpenSSL 0.9.8 or later; +virtual host scope available if using OpenSSL 1.0.0 or later. +The default used to be `on` in version 2.4.3.

This directive allows to enable compression on the SSL level.

Enabling compression causes security issues in most setups (the so called +CRIME attack).

+ +

SSLCryptoDevice Directive

+ + + + + + + +

Description:	Enable use of a cryptographic hardware accelerator
Syntax:	`SSLCryptoDevice engine`
Default:	`SSLCryptoDevice builtin`
Context:	server config
Status:	Extension
Module:	mod_ssl

+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.

+ +

To discover which engine names are supported, run the command +"openssl engine".

+ +

Example

# For a Broadcom accelerator:
+SSLCryptoDevice ubsec

+ +

SSLEngine Directive

+ + + + + + + +

Description:	SSL Engine Operation Switch
Syntax:	`SSLEngine on\|off\|optional`
Default:	`SSLEngine off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+This directive toggles the usage of the SSL/TLS Protocol Engine. This +is should be used inside a <VirtualHost> 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.

Example

<VirtualHost _default_:443>
+SSLEngine on
+#...
+</VirtualHost>

In Apache 2.1 and later, SSLEngine can be set to +optional. This enables support for +RFC 2817, Upgrading to TLS +Within HTTP/1.1. At this time no web browsers support RFC 2817.

+ +

SSLFIPS Directive

+ + + + + + + +

Description:	SSL FIPS mode Switch
Syntax:	`SSLFIPS on\|off`
Default:	`SSLFIPS off`
Context:	server config
Status:	Extension
Module:	mod_ssl

+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. +

+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 +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. +

+ +

SSLHonorCipherOrder Directive

+ + + + + + + +

Description:	Option to prefer the server's cipher preference order
Syntax:	`SSLHonorCipherOrder on\|off`
Default:	`SSLHonorCipherOrder off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

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.

Example

SSLHonorCipherOrder on

+ +

SSLInsecureRenegotiation Directive

+ + + + + + + + +

Description:	Option to enable support for insecure renegotiation
Syntax:	`SSLInsecureRenegotiation on\|off`
Default:	`SSLInsecureRenegotiation off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	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 +attack +(CVE-2009-3555) +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.

+ +

If mod_ssl 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 +in CVE-2009-3555.

+ +

Example

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.

+ + +

SSLOCSPDefaultResponder Directive

+ + + + + + +

Description:	Set the default responder URI for OCSP validation
Syntax:	`SSLOCSDefaultResponder uri`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

This option sets the default OCSP responder to use. If SSLOCSPOverrideResponder is not enabled, +the URI given will be used only if no responder URI is specified in +the certificate being verified.

+ +

SSLOCSPEnable Directive

+ + + + + + + + +

Description:	Enable OCSP validation of the client certificate chain
Syntax:	`SSLOCSPEnable on\|leaf\|off`
Default:	`SSLOCSPEnable off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Mode leaf available in httpd 2.4.34 and later

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. In +mode 'leaf', only the client certificate itself will be validated.

+ +

The OCSP responder used is either extracted from the certificate +itself, or derived by configuration; see the +SSLOCSPDefaultResponder and +SSLOCSPOverrideResponder +directives.

+ +

Example

SSLVerifyClient on
+SSLOCSPEnable on
+SSLOCSPDefaultResponder "http://responder.example.com:8888/responder"
+SSLOCSPOverrideResponder on

+ +

SSLOCSPNoverify Directive

+ + + + + + + + +

Description:	skip the OCSP responder certificates verification
Syntax:	`SSLOCSPNoverify On/Off`
Default:	`SSLOCSPNoverify Off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.26 and later, if using OpenSSL 0.9.7 or later

Skip the OCSP responder certificates verification, mostly useful when +testing an OCSP server.

+ +

SSLOCSPOverrideResponder Directive

+ + + + + + + +

Description:	Force use of the default responder URI for OCSP validation
Syntax:	`SSLOCSPOverrideResponder on\|off`
Default:	`SSLOCSPOverrideResponder off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

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.

+ +

SSLOCSPProxyURL Directive

+ + + + + + + +

Description:	Proxy URL to use for OCSP requests
Syntax:	`SSLOCSPProxyURL url`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.19 and later

This option allows to set the URL of a HTTP proxy that should be used for +all queries to OCSP responders.

+ +

SSLOCSPResponderCertificateFile Directive

+ + + + + + + +

Description:	Set of trusted PEM encoded OCSP responder certificates
Syntax:	`SSLOCSPResponderCertificateFile file`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.26 and later, if using OpenSSL 0.9.7 or later

This supplies a list of trusted OCSP responder certificates to be used +during OCSP responder certificate validation. The supplied certificates are +implicitly trusted without any further validation. This is typically used +where the OCSP responder certificate is self signed or omitted from the OCSP +response.

+ +

SSLOCSPResponderTimeout Directive

+ + + + + + + +

Description:	Timeout for OCSP queries
Syntax:	`SSLOCSPResponderTimeout seconds`
Default:	`SSLOCSPResponderTimeout 10`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

This option sets the timeout for queries to OCSP responders, when +SSLOCSPEnable is turned on.

+ +

SSLOCSPResponseMaxAge Directive

+ + + + + + + +

Description:	Maximum allowable age for OCSP responses
Syntax:	`SSLOCSPResponseMaxAge seconds`
Default:	`SSLOCSPResponseMaxAge -1`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

This option sets the maximum allowable age ("freshness") for OCSP responses. +The default value (-1) does not enforce a maximum age, +which means that OCSP responses are considered valid as long as their +nextUpdate field is in the future.

+ +

SSLOCSPResponseTimeSkew Directive

+ + + + + + + +

Description:	Maximum allowable time skew for OCSP response validation
Syntax:	`SSLOCSPResponseTimeSkew seconds`
Default:	`SSLOCSPResponseTimeSkew 300`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

This option sets the maximum allowable time skew for OCSP responses +(when checking their thisUpdate and nextUpdate fields).

+ +

SSLOCSPUseRequestNonce Directive

+ + + + + + + + +

Description:	Use a nonce within OCSP queries
Syntax:	`SSLOCSPUseRequestNonce on\|off`
Default:	`SSLOCSPUseRequestNonce on`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.10 and later

This option determines whether queries to OCSP responders should contain +a nonce or not. By default, a query nonce is always used and checked against +the response's one. When the responder does not use nonces (e.g. Microsoft OCSP +Responder), this option should be turned off.

+ +

SSLOpenSSLConfCmd Directive

+ + + + + + + +

Description:	Configure OpenSSL parameters through its SSL_CONF API
Syntax:	`SSLOpenSSLConfCmd command-name command-value`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.8 and later, if using OpenSSL 1.0.2 or later

This directive exposes OpenSSL's SSL_CONF API to mod_ssl, +allowing a flexible configuration of OpenSSL parameters without the need +of implementing additional mod_ssl directives when new +features are added to OpenSSL.

+ +

The set of available SSLOpenSSLConfCmd commands +depends on the OpenSSL version being used for mod_ssl +(at least version 1.0.2 is required). For a list of supported command +names, see the section Supported configuration file commands in the +SSL_CONF_cmd(3) manual page for OpenSSL.

+ +

Some of the SSLOpenSSLConfCmd commands can be used +as an alternative to existing directives (such as +SSLCipherSuite or +SSLProtocol), +though it should be noted that the syntax / allowable values for the parameters +may sometimes differ.

+ +

Examples

SSLOpenSSLConfCmd Options -SessionTicket,ServerPreference
+SSLOpenSSLConfCmd ECDHParameters brainpoolP256r1
+SSLOpenSSLConfCmd ServerInfoFile "/usr/local/apache2/conf/server-info.pem"
+SSLOpenSSLConfCmd Protocol "-ALL, TLSv1.2"
+SSLOpenSSLConfCmd SignatureAlgorithms RSA+SHA384:ECDSA+SHA256

+ +

SSLOptions Directive

+ + + + + + + +

Description:	Configure various SSL engine run-time options
Syntax:	`SSLOptions [+\|-]option ...`
Context:	server config, virtual host, directory, .htaccess
Override:	Options
Status:	Extension
Module:	mod_ssl

+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 +completely; 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 + demand.
+
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/''.
+ +
Note that the AuthBasicFake + directive within mod_auth_basic can be used as a more + general mechanism for faking basic authentication, giving control over the + structure of both the username and password.
+
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 may not be what the user expects, so enable this on a + per-directory basis only, please.
+
LegacyDNStringFormat +
+ This option influences how values of the + SSL_{CLIENT,SERVER}_{I,S}_DN 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.
+ +
If LegacyDNStringFormat 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. +
+

Example

SSLOptions +FakeBasicAuth -StrictRequire
+<Files ~ "\.(cgi|shtml)$">
+    SSLOptions +StdEnvVars -ExportCertData
+</Files>

+ +

SSLPassPhraseDialog Directive

+ + + + + + + +

Description:	Type of pass phrase dialog for encrypted private +keys
Syntax:	`SSLPassPhraseDialog type`
Default:	`SSLPassPhraseDialog builtin`
Context:	server config
Status:	Extension
Module:	mod_ssl

+When Apache starts up it has to read the various Certificate (see +SSLCertificateFile) and +Private Key (see SSLCertificateKeyFile) 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 +type:

builtin +
+ 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 particular input device; the program is sent the standard + prompt text used for the builtin mode on + stdin, and is expected to write password strings on + stdout. 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'', ``ECC'' or an + integer index starting at 3 if more than three keys are configured), which + indicate for which server and algorithm it has to print the corresponding + Pass Phrase to stdout. In versions 2.4.8 (unreleased) + and 2.4.9, it is called with one argument, a string of the + form ``servername:portnumber:index'' (with index + being a zero-based integer number), which indicate the server, TCP port + and certificate number. 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.

Example

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

+ +

SSLProtocol Directive

+ + + + + + + +

Description:	Configure usable SSL/TLS protocol versions
Syntax:	`SSLProtocol [+\|-]protocol ...`
Default:	`SSLProtocol all -SSLv3 (up to 2.4.16: all)`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl

+This directive can be used to control which versions of the SSL/TLS protocol +will be accepted in new connections.

+The available (case-insensitive) protocols are:

SSLv3 +
+ 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, but is + deprecated in RFC 7568.
TLSv1 +
+ This is the Transport Layer Security (TLS) protocol, version 1.0. + It is the successor to SSLv3 and is defined in + RFC 2246. + It is supported by nearly every client.
TLSv1.1 (when using OpenSSL 1.0.1 and later) +
+ A revision of the TLS 1.0 protocol, as defined in + RFC 4346.
TLSv1.2 (when using OpenSSL 1.0.1 and later) +
+ A revision of the TLS 1.1 protocol, as defined in + RFC 5246.
TLSv1.3 (when using OpenSSL 1.1.1 and later) +
+ A new version of the TLS protocol, as defined in + RFC 8446.
all +
+ This is a shortcut for ``+SSLv3 +TLSv1'' or + - when using OpenSSL 1.0.1 and later - + ``+SSLv3 +TLSv1 +TLSv1.1 +TLSv1.2'', respectively + (except for OpenSSL versions compiled with the ``no-ssl3'' configuration + option, where all does not include +SSLv3).

Example

SSLProtocol TLSv1

+ +

SSLProxyCACertificateFile Directive

+ + + + + + +

Description:	File of concatenated PEM-encoded CA Certificates +for Remote Server Auth
Syntax:	`SSLProxyCACertificateFile file-path`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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 +SSLProxyCACertificatePath.

Example

SSLProxyCACertificateFile "/usr/local/apache2/conf/ssl.crt/ca-bundle-remote-server.crt"

+ +

SSLProxyCACertificatePath Directive

+ + + + + + +

Description:	Directory of PEM-encoded CA Certificates for +Remote Server Auth
Syntax:	`SSLProxyCACertificatePath directory-path`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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.

Example

SSLProxyCACertificatePath "/usr/local/apache2/conf/ssl.crt/"

+ +

SSLProxyCARevocationCheck Directive

+ + + + + + + +

Description:	Enable CRL-based revocation checking for Remote Server Auth
Syntax:	`SSLProxyCARevocationCheck chain\|leaf\|none`
Default:	`SSLProxyCARevocationCheck none`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+Enables certificate revocation list (CRL) checking for the +remote servers you deal with. At least one of +SSLProxyCARevocationFile +or SSLProxyCARevocationPath must be +configured. When set to chain (recommended setting), +CRL checks are applied to all certificates in the chain, while setting it to +leaf limits the checks to the end-entity cert. +

When set to `chain` or `leaf`, +CRLs must be available for successful validation

+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 +SSLProxyCARevocationFile +or SSLProxyCARevocationPath. +With the introduction of this directive, the behavior has been changed: +when checking is enabled, CRLs must be present for the validation +to succeed - otherwise it will fail with an +"unable to get certificate CRL" error. +

Example

SSLProxyCARevocationCheck chain

+ +

SSLProxyCARevocationFile Directive

+ + + + + + +

Description:	File of concatenated PEM-encoded CA CRLs for +Remote Server Auth
Syntax:	`SSLProxyCARevocationFile file-path`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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 SSLProxyCARevocationPath.

Example

SSLProxyCARevocationFile "/usr/local/apache2/conf/ssl.crl/ca-bundle-remote-server.crl"

+ +

SSLProxyCARevocationPath Directive

+ + + + + + +

Description:	Directory of PEM-encoded CA CRLs for +Remote Server Auth
Syntax:	`SSLProxyCARevocationPath directory-path`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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.

Example

SSLProxyCARevocationPath "/usr/local/apache2/conf/ssl.crl/"

+ +

SSLProxyCheckPeerCN Directive

+ + + + + + + +

Description:	Whether to check the remote server certificate's CN field +
Syntax:	`SSLProxyCheckPeerCN on\|off`
Default:	`SSLProxyCheckPeerCN on`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+This directive sets whether the remote server certificate's 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 is +superseded by SSLProxyCheckPeerName +in release 2.4.5 and later. +

+In all releases 2.4.5 through 2.4.20, setting +SSLProxyCheckPeerName off was sufficient to enable this behavior +(as the SSLProxyCheckPeerCN default was on.) In +these releases, both directives must be set to off to completely +avoid remote server certificate name validation. Many users reported this +to be very confusing. +

+As of release 2.4.21, all configurations which enable either one of the +SSLProxyCheckPeerName or SSLProxyCheckPeerCN options +will use the new SSLProxyCheckPeerName +behavior, and all configurations which disable either one of the +SSLProxyCheckPeerName or SSLProxyCheckPeerCN options +will suppress all remote server certificate name validation. Only the following +configuration will trigger the legacy certificate CN comparison in 2.4.21 and +later releases; +

Example

SSLProxyCheckPeerCN on
+SSLProxyCheckPeerName off

+ +

SSLProxyCheckPeerExpire Directive

+ + + + + + + +

Description:	Whether to check if remote server certificate is expired +
Syntax:	`SSLProxyCheckPeerExpire on\|off`
Default:	`SSLProxyCheckPeerExpire on`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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. +

Example

SSLProxyCheckPeerExpire on

+ +

SSLProxyCheckPeerName Directive

+ + + + + + + + +

Description:	Configure host name checking for remote server certificates +
Syntax:	`SSLProxyCheckPeerName on\|off`
Default:	`SSLProxyCheckPeerName on`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl
Compatibility:	Apache HTTP Server 2.4.5 and later

+This directive configures host name checking for server certificates when +mod_ssl is acting as an SSL client. The check will succeed if the host name +from the request URI matches one of the CN attribute(s) of the certificate's +subject, or matches the subjectAltName extension. If the check fails, the SSL +request is aborted and a 502 status code (Bad Gateway) is returned. +

+Wildcard matching is supported for specific cases: an subjectAltName entry +of type dNSName, or CN attributes starting with *. will match +with any host name of the same number of name elements and the same suffix. +E.g. *.example.org will match foo.example.org, +but will not match foo.bar.example.org, because the number of +elements in the respective host names differs. +

+This feature was introduced in 2.4.5 and superseded the behavior of the +SSLProxyCheckPeerCN directive, which +only tested the exact value in the first CN attribute against the host name. +However, many users were confused by the behavior of using these directives +individually, so the mutual behavior of SSLProxyCheckPeerName +and SSLProxyCheckPeerCN directives were improved in release +2.4.21. See the SSLProxyCheckPeerCN +directive description for the original behavior and details of these +improvements. +

+ +

SSLProxyCipherSuite Directive

+ + + + + + + +

Description:	Cipher Suite available for negotiation in SSL +proxy handshake
Syntax:	`SSLProxyCipherSuite [protocol] cipher-spec`
Default:	`SSLProxyCipherSuite ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+EXP`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

Equivalent to SSLCipherSuite, but +for the proxy connection. +Please refer to SSLCipherSuite +for additional information.

+ +

SSLProxyEngine Directive

+ + + + + + + +

Description:	SSL Proxy Engine Operation Switch
Syntax:	`SSLProxyEngine on\|off`
Default:	`SSLProxyEngine off`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+This directive toggles the usage of the SSL/TLS Protocol Engine for proxy. This +is usually used inside a <VirtualHost> 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 ProxyRequests directives). +SSLProxyEngine is not required to enable a forward proxy +server to proxy SSL/TLS requests.

+ +

Example

<VirtualHost _default_:443>
+    SSLProxyEngine on
+    #...
+</VirtualHost>

+ +

SSLProxyMachineCertificateChainFile Directive

+ + + + + + +

Description:	File of concatenated PEM-encoded CA certificates to be used by the proxy for choosing a certificate
Syntax:	`SSLProxyMachineCertificateChainFile filename`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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 +SSLProxyCACertificateFile.

Example

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

+ +

SSLProxyMachineCertificateFile Directive

+ + + + + + +

Description:	File of concatenated PEM-encoded client certificates and keys to be used by the proxy
Syntax:	`SSLProxyMachineCertificateFile filename`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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

Example

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

+ +

SSLProxyMachineCertificatePath Directive

+ + + + + + +

Description:	Directory of PEM-encoded client certificates and keys to be used by the proxy
Syntax:	`SSLProxyMachineCertificatePath directory`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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

Example

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

+ +

SSLProxyProtocol Directive

+ + + + + + + +

Description:	Configure usable SSL protocol flavors for proxy usage
Syntax:	`SSLProxyProtocol [+\|-]protocol ...`
Default:	`SSLProxyProtocol all -SSLv3 (up to 2.4.16: all)`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+ +

+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 SSLProtocol +for additional information. +

+ +

SSLProxyVerify Directive

+ + + + + + + +

Description:	Type of remote server Certificate verification
Syntax:	`SSLProxyVerify level`
Default:	`SSLProxyVerify none`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+ +

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.

+The following levels are available for level:

none: + no remote server Certificate is required at all
optional: + the remote server may present a valid Certificate
require: + 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.)

Example

SSLProxyVerify require

+ +

SSLProxyVerifyDepth Directive

+ + + + + + + +

Description:	Maximum depth of CA Certificates in Remote Server +Certificate verification
Syntax:	`SSLProxyVerifyDepth number`
Default:	`SSLProxyVerifyDepth 1`
Context:	server config, virtual host, proxy section
Status:	Extension
Module:	mod_ssl

+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 +SSLProxyCACertificatePath), etc.

Example

SSLProxyVerifyDepth 10

+ +

SSLRandomSeed Directive

+ + + + + + +

Description:	Pseudo Random Number Generator (PRNG) seeding +source
Syntax:	`SSLRandomSeed context source +[bytes]`
Context:	server config
Status:	Extension
Module:	mod_ssl

+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:

builtin +
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 a randomly + chosen 128 bytes extract of the stack. + 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.
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 http://www.lothar.com/tech + /crypto/) to seed the PRNG. Use this if no random device exists + on your platform.

Example

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

+ +

SSLRenegBufferSize Directive

+ + + + + + + + +

Description:	Set the size for the SSL renegotiation buffer
Syntax:	`SSLRenegBufferSize bytes`
Default:	`SSLRenegBufferSize 131072`
Context:	directory, .htaccess
Override:	AuthConfig
Status:	Extension
Module:	mod_ssl

+ +

If an SSL renegotiation is required in per-location context, for +example, any use of SSLVerifyClient in a Directory or +Location block, then mod_ssl 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. +

+ +

Example

SSLRenegBufferSize 262144

+ +

SSLRequire Directive

+ + + + + + + +

Description:	Allow access only when an arbitrarily complex +boolean expression is true
Syntax:	`SSLRequire expression`
Context:	directory, .htaccess
Override:	AuthConfig
Status:	Extension
Module:	mod_ssl

+ +

SSLRequire is deprecated

SSLRequire is deprecated and should in general be replaced +by Require expr. The so called +ap_expr syntax of Require expr is +a superset of the syntax of SSLRequire, with the following +exception:

+ +

In SSLRequire, the comparison operators <, +<=, ... are completely equivalent to the operators +lt, le, ... and work in a somewhat peculiar way that +first compares the length of two strings and then the lexical order. +On the other hand, ap_expr has two sets of +comparison operators: The operators <, +<=, ... do lexical string comparison, while the operators +-lt, -le, ... do integer comparison. +For the latter, there are also aliases without the leading dashes: +lt, le, ... +

+ +

+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 expression must match the following syntax (given as a BNF +grammar notation):

expr     ::= "true" | "false"
+           | "!" expr
+           | expr "&&" expr
+           | expr "||" expr
+           | "(" expr ")"
+           | comp
+
+comp     ::= 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" "PeerExtList(" word ")"
+           | word "=~" regex
+           | word "!~" regex
+
+wordlist ::= word
+           | wordlist "," word
+
+word     ::= digit
+           | cstring
+           | variable
+           | function
+
+digit    ::= [0-9]+
+cstring  ::= "..."
+variable ::= "%{" varname "}"
+function ::= funcname "(" funcargs ")"

For varname any of the variables described in Environment Variables can be used. For +funcname the available functions are listed in +the ap_expr documentation.

+ +

The expression is parsed into an internal machine +representation when the configuration is loaded, and then evaluated +during request processing. In .htaccess context, the expression is +both parsed and executed each time the .htaccess file is encountered during +request processing.

+ +

Example

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} -ge 1 and %{TIME_WDAY} -le 5          \
+            and %{TIME_HOUR} -ge 8 and %{TIME_HOUR} -le 20       ) \
+           or %{REMOTE_ADDR} =~ m/^192\.76\.162\.[0-9]+$/

+ +

The PeerExtList(object-ID) function expects +to find zero or more instances of the X.509 certificate extension +identified by the given object ID (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).

+ +

Example

SSLRequire "foobar" in PeerExtList("1.2.3.4.5.6")

+ +

Notes on the PeerExtList function

+ +

The object ID can be specified either as a descriptive +name recognized by the SSL library, such as "nsComment", +or as a numeric OID, such as "1.2.3.4.5.6".
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.

+ + +

SSLRequireSSL Directive

+ + + + + + + +

Description:	Deny access when SSL is not used for the +HTTP request
Syntax:	`SSLRequireSSL`
Context:	directory, .htaccess
Override:	AuthConfig
Status:	Extension
Module:	mod_ssl

+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.

Example

SSLRequireSSL

+ +

SSLSessionCache Directive

+ + + + + + + +

Description:	Type of the global/inter-process SSL Session +Cache
Syntax:	`SSLSessionCache type`
Default:	`SSLSessionCache none`
Context:	server config
Status:	Extension
Module:	mod_ssl

+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 five storage types are currently supported:

none + +
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.
nonenotnull + +
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.
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. To use this, ensure that + mod_socache_dbm is loaded.
shmcb:/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. To use this, + ensure that mod_socache_shmcb is loaded.
dc:UNIX:/path/to/socket + +
This makes use of the distcache 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, UNIX:/path/to/socket specifies a UNIX + domain socket (typically a local dc_client proxy); + IP:server.example.com:9001 specifies an IP + address. To use this, ensure that + mod_socache_dc is loaded.

+ +

Examples

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

+ +

The ssl-cache mutex is used to serialize access to +the session cache to prevent corruption. This mutex can be configured +using the Mutex directive.

+ +

SSLSessionCacheTimeout Directive

+ + + + + + + + +

Description:	Number of seconds before an SSL session expires +in the Session Cache
Syntax:	`SSLSessionCacheTimeout seconds`
Default:	`SSLSessionCacheTimeout 300`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Applies also to RFC 5077 TLS session resumption in Apache 2.4.10 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.

Example

SSLSessionCacheTimeout 600

+ +

SSLSessionTicketKeyFile Directive

+ + + + + + + +

Description:	Persistent encryption/decryption key for TLS session tickets
Syntax:	`SSLSessionTicketKeyFile file-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.0 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 +RFC 5077. +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 +SSLCertificateKeyFile.

+ +

SSLSessionTickets Directive

+ + + + + + + + +

Description:	Enable or disable use of TLS session tickets
Syntax:	`SSLSessionTickets on\|off`
Default:	`SSLSessionTickets on`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.11 and later, if using OpenSSL 0.9.8f +or later.

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.

+ +

SSLSRPUnknownUserSeed Directive

+ + + + + + + +

Description:	SRP unknown user seed
Syntax:	`SSLSRPUnknownUserSeed secret-string`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.4 and later, if using OpenSSL 1.0.1 or +later

+This directive sets the seed used to fake SRP user parameters for unknown +users, to avoid leaking whether a given user exists. Specify a secret +string. If this directive is not used, then Apache will return the +UNKNOWN_PSK_IDENTITY alert to clients who specify an unknown username. +

Example

+SSLSRPUnknownUserSeed "secret" +

+ +

SSLSRPVerifierFile Directive

+ + + + + + + +

Description:	Path to SRP verifier file
Syntax:	`SSLSRPVerifierFile file-path`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available in httpd 2.4.4 and later, if using OpenSSL 1.0.1 or +later

+This directive enables TLS-SRP and sets the path to the OpenSSL SRP (Secure +Remote Password) verifier file containing TLS-SRP usernames, verifiers, salts, +and group parameters.

Example

+SSLSRPVerifierFile "/path/to/file.srpv" +

+The verifier file can be created with the openssl command line +utility:

Creating the SRP verifier file

+openssl srp -srpvfile passwd.srpv -userinfo "some info" -add username +

The value given with the optional -userinfo parameter is +avalable in the SSL_SRP_USERINFO request environment variable.

+ + +

SSLStaplingCache Directive

+ + + + + + + +

Description:	Configures the OCSP stapling cache
Syntax:	`SSLStaplingCache type`
Context:	server config
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

Configures the cache used to store OCSP responses which get included +in the TLS handshake if SSLUseStapling +is enabled. Configuration of a cache is mandatory for OCSP stapling. +With the exception of none and nonenotnull, +the same storage types are supported as with +SSLSessionCache.

+ +

SSLStaplingErrorCacheTimeout Directive

+ + + + + + + + +

Description:	Number of seconds before expiring invalid responses in the OCSP stapling cache
Syntax:	`SSLStaplingErrorCacheTimeout seconds`
Default:	`SSLStaplingErrorCacheTimeout 600`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

Sets the timeout in seconds before invalid responses +in the OCSP stapling cache (configured through SSLStaplingCache) will expire. +To set the cache timeout for valid responses, see +SSLStaplingStandardCacheTimeout.

+ +

SSLStaplingFakeTryLater Directive

+ + + + + + + + +

Description:	Synthesize "tryLater" responses for failed OCSP stapling queries
Syntax:	`SSLStaplingFakeTryLater on\|off`
Default:	`SSLStaplingFakeTryLater on`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

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 SSLStaplingReturnResponderErrors +is also enabled.

+ +

SSLStaplingForceURL Directive

+ + + + + + + +

Description:	Override the OCSP responder URI specified in the certificate's AIA extension
Syntax:	`SSLStaplingForceURL uri`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

This directive overrides the URI of an OCSP responder as obtained from +the authorityInfoAccess (AIA) extension of the certificate. +One potential use is when a proxy is used for retrieving OCSP queries.

+ +

SSLStaplingResponderTimeout Directive

+ + + + + + + + +

Description:	Timeout for OCSP stapling queries
Syntax:	`SSLStaplingResponderTimeout seconds`
Default:	`SSLStaplingResponderTimeout 10`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

This option sets the timeout for queries to OCSP responders when +SSLUseStapling is enabled +and mod_ssl is querying a responder for OCSP stapling purposes.

+ +

SSLStaplingResponseMaxAge Directive

+ + + + + + + + +

Description:	Maximum allowable age for OCSP stapling responses
Syntax:	`SSLStaplingResponseMaxAge seconds`
Default:	`SSLStaplingResponseMaxAge -1`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

This option sets the maximum allowable age ("freshness") when +considering OCSP responses for stapling purposes, i.e. when +SSLUseStapling is turned on. +The default value (-1) does not enforce a maximum age, +which means that OCSP responses are considered valid as long as their +nextUpdate field is in the future.

+ +

SSLStaplingResponseTimeSkew Directive

+ + + + + + + + +

Description:	Maximum allowable time skew for OCSP stapling response validation
Syntax:	`SSLStaplingResponseTimeSkew seconds`
Default:	`SSLStaplingResponseTimeSkew 300`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

This option sets the maximum allowable time skew when mod_ssl checks the +thisUpdate and nextUpdate fields of OCSP responses +which get included in the TLS handshake (OCSP stapling). Only applicable +if SSLUseStapling is turned on.

+ +

SSLStaplingReturnResponderErrors Directive

+ + + + + + + + +

Description:	Pass stapling related OCSP errors on to client
Syntax:	`SSLStaplingReturnResponderErrors on\|off`
Default:	`SSLStaplingReturnResponderErrors on`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

When enabled, mod_ssl will pass responses from unsuccessful +stapling related OCSP queries (such as responses with an overall status +other than "successful", responses with a certificate status other than +"good", expired responses etc.) on to the client. +If set to off, only responses indicating a certificate status +of "good" will be included in the TLS handshake.

+ +

SSLStaplingStandardCacheTimeout Directive

+ + + + + + + + +

Description:	Number of seconds before expiring responses in the OCSP stapling cache
Syntax:	`SSLStaplingStandardCacheTimeout seconds`
Default:	`SSLStaplingStandardCacheTimeout 3600`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

Sets the timeout in seconds before responses in the OCSP stapling cache +(configured through SSLStaplingCache) +will expire. This directive applies to valid responses, while +SSLStaplingErrorCacheTimeout is +used for controlling the timeout for invalid/unavailable responses. +

+ +

SSLStrictSNIVHostCheck Directive

+ + + + + + + + +

Description:	Whether to allow non-SNI clients to access a name-based virtual +host. +
Syntax:	`SSLStrictSNIVHostCheck on\|off`
Default:	`SSLStrictSNIVHostCheck off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	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 default name-based virtual +host, clients that are SNI unaware will not be allowed to access any +virtual host, belonging to this particular IP / port combination. +If set to on in any other virtual host, SNI unaware clients +are not allowed to access this particular virtual host. +

+ +

+This option is only available if httpd was compiled against an SNI capable +version of OpenSSL. +

+ +

Example

SSLStrictSNIVHostCheck on

+ +

SSLUserName Directive

+ + + + + + + +

Description:	Variable name to determine user name
Syntax:	`SSLUserName varname`
Context:	server config, directory, .htaccess
Override:	AuthConfig
Status:	Extension
Module:	mod_ssl

+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 SSL environment variables.

+ +

Note that this directive has no effect if the +FakeBasicAuth option is used (see SSLOptions).

+ +

Example

SSLUserName SSL_CLIENT_S_DN_CN

+ +

SSLUseStapling Directive

+ + + + + + + + +

Description:	Enable stapling of OCSP responses in the TLS handshake
Syntax:	`SSLUseStapling on\|off`
Default:	`SSLUseStapling off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_ssl
Compatibility:	Available if using OpenSSL 0.9.8h or later

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 +SSLStaplingCache is a +prerequisite for enabling OCSP stapling.

+ +

OCSP stapling relieves the client of querying the OCSP responder +on its own, but it should be noted that with the RFC 6066 specification, +the server's CertificateStatus 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 implementation therefore only partially achieves the +stated goal of "saving roundtrips and resources" - see also +RFC 6961 +(TLS Multiple Certificate Status Extension). +

+ +

When OCSP stapling is enabled, the ssl-stapling mutex is used +to control access to the OCSP stapling cache in order to prevent corruption, +and the sss-stapling-refresh mutex is used to control refreshes +of OCSP responses. These mutexes can be configured using the +Mutex directive. +

+ + +

SSLVerifyClient Directive

+ + + + + + + + +

Description:	Type of Client Certificate verification
Syntax:	`SSLVerifyClient level`
Default:	`SSLVerifyClient none`
Context:	server config, virtual host, directory, .htaccess
Override:	AuthConfig
Status:	Extension
Module:	mod_ssl

+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:

none: + no client Certificate is required at all
optional: + the client may present a valid Certificate
require: + 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. This option + cannot be relied upon for client authentication.

Example

SSLVerifyClient require

+ +

SSLVerifyDepth Directive

+ + + + + + + + +

Description:	Maximum depth of CA Certificates in Client +Certificate verification
Syntax:	`SSLVerifyDepth number`
Default:	`SSLVerifyDepth 1`
Context:	server config, virtual host, directory, .htaccess
Override:	AuthConfig
Status:	Extension
Module:	mod_ssl

+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 +SSLCACertificatePath), etc.

Example

SSLVerifyDepth 10

+ +

Apache Module mod_ssl

Summary

Topics

Directives

Bugfix checklist

See also

Example

Example (using mod_headers)

Example

Example

Example

Example

Example

Compatibility with versions 2.2

Example

Example

SSLCertificateChainFile is deprecated

Example

DH parameter interoperability with primes > 1024 bit

Default DH parameters when using multiple certificates and OpenSSL +versions prior to 1.0.2

Example

Example

aNULL, eNULL and EXP +ciphers are always disabled

Example

Example

Example

Example

Security warning

Example

Example

Examples

Example

Example

Example

Example

Example

When set to chain or leaf, +CRLs must be available for successful validation

Example

Example

Example

Example

Example

Example

Security warning

Example

Example

Example

Example

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Example

SSLRequire is deprecated

Example

Example

Notes on the PeerExtList function

See also

Example

Examples

Example

Example

Example

Creating the SRP verifier file

Example

Example

Example

Example

Example (using `mod_headers`)

`aNULL`, `eNULL` and `EXP` +ciphers are always disabled

When set to `chain` or `leaf`, +CRLs must be available for successful validation