OPENSSL_config.3ssl - Man Page

simple OpenSSL configuration functions


 #include <openssl/conf.h>

 #if OPENSSL_API_COMPAT < 0x10100000L
 void OPENSSL_config(const char *appname);
 void OPENSSL_no_config(void);


OPENSSL_config() configures OpenSSL using the standard openssl.cnf and reads from the application section appname. If appname is NULL then the default section, openssl_conf, will be used. Errors are silently ignored. Multiple calls have no effect.

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

If the application is built with OPENSSL_LOAD_CONF defined, then a call to OpenSSL_add_all_algorithms() will implicitly call OPENSSL_config() first.


The OPENSSL_config() function is designed to be a very simple “call it and forget it” function. It is however much better than nothing. Applications which need finer control over their configuration functionality should use the configuration functions such as CONF_modules_load() directly. This function is deprecated and its use should be avoided. Applications should instead call CONF_modules_load() during initialization (that is before starting any threads).

There are several reasons why calling the OpenSSL configuration routines is advisable. For example, 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.



The path to the config file. Ignored in set-user-ID and set-group-ID programs.

Return Values

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

See Also

config(5), CONF_modules_load_file(3)


The OPENSSL_no_config() and OPENSSL_config() functions were deprecated in OpenSSL 1.1.0 by OPENSSL_init_crypto().

Referenced By

CONF_modules_free.3ssl(3), CONF_modules_load_file.3ssl(3), OPENSSL_load_builtin_modules.3ssl(3).

The man page OPENSSL_no_config.3ssl(3) is an alias of OPENSSL_config.3ssl(3).

2021-03-26 1.1.1k OpenSSL