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OPENSSL_config(3)                   OpenSSL                  OPENSSL_config(3)



NAME
       OPENSSL_config, OPENSSL_no_config - simple OpenSSL configuration
       functions

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/conf.h>

        void OPENSSL_config(const char *config_name);
        void OPENSSL_no_config(void);

DESCRIPTION
       OPENSSL_config() configures OpenSSL using the standard openssl.cnf
       configuration file name using config_name. If config_name is NULL then
       the default name openssl_conf will be used. Any errors are ignored.
       Further calls to OPENSSL_config() will have no effect. The
       configuration file format is documented in the conf(5) manual page.

       OPENSSL_no_config() disables configuration. If called before
       OPENSSL_config() no configuration takes place.

NOTES
       It is strongly recommended that all new applications call
       OPENSSL_config() or the more sophisticated functions such as
       CONF_modules_load() during initialization (that is before starting any
       threads). By doing this an application does not need to keep track of
       all configuration options and some new functionality can be supported
       automatically.

       It is also possible to automatically call OPENSSL_config() when an
       application calls OPENSSL_add_all_algorithms() by compiling an
       application with the preprocessor symbol OPENSSL_LOAD_CONF #define'd.
       In this way configuration can be added without source changes.

       The environment variable OPENSSL_CONF can be set to specify the
       location of the configuration file.

       Currently ASN1 OBJECTs and ENGINE configuration can be performed future
       versions of OpenSSL will add new configuration options.

       There are several reasons why calling the OpenSSL configuration
       routines is advisable. For example new ENGINE functionality was added
       to OpenSSL 0.9.7.  In OpenSSL 0.9.7 control functions can be supported
       by ENGINEs, this can be used (among other things) to load dynamic
       ENGINEs from shared libraries (DSOs).  However very few applications
       currently support the control interface and so very few can load and
       use dynamic ENGINEs. Equally in future more sophisticated ENGINEs will
       require certain control operations to customize them. If an application
       calls OPENSSL_config() it doesn't need to know or care about ENGINE
       control operations because they can be performed by editing a
       configuration file.

       Applications should free up configuration at application closedown by
       calling CONF_modules_free().

RESTRICTIONS
       The OPENSSL_config() function is designed to be a very simple "call it
       and forget it" function. As a result its behaviour is somewhat limited.
       It ignores all errors silently and it can only load from the standard
       configuration file location for example.

       It is however much better than nothing. Applications which need finer
       control over their configuration functionality should use the
       configuration functions such as CONF_load_modules() directly.

RETURN VALUES
       Neither OPENSSL_config() nor OPENSSL_no_config() return a value.

SEE ALSO
       conf(5), CONF_load_modules_file(3), CONF_modules_free(3)

HISTORY
       OPENSSL_config() and OPENSSL_no_config() first appeared in OpenSSL
       0.9.7



1.0.1i                            2014-06-05                 OPENSSL_config(3)