OPENSSL\_CONFIG(3ossl) OpenSSL OPENSSL\_CONFIG(3ossl)

# [NAME](#NAME)

OPENSSL\_config, OPENSSL\_no\_config - simple OpenSSL configuration functions

# [SYNOPSIS](#SYNOPSIS)

```
 #include <openssl/conf.h>
```

The following functions have been deprecated since OpenSSL 1.1.0, and can be hidden entirely by defining **OPENSSL\_API\_COMPAT** with a suitable version value, see [**openssl\_user\_macros**(7)](/man/os/openssl-4.0/openssl_user_macros.7):

```
 void OPENSSL_config(const char *appname);
 void OPENSSL_no_config(void);
```

# [DESCRIPTION](#DESCRIPTION)

**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.

# [NOTES](#NOTES)

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).

# [ENVIRONMENT](#ENVIRONMENT)

[**OPENSSL\_CONF**](#OPENSSL_CONF)

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

# [RETURN VALUES](#RETURN_VALUES)

Neither **OPENSSL\_config()** nor **OPENSSL\_no\_config()** return a value.

# [SEE ALSO](#SEE_ALSO)

[**config**(5)](/man/os/openssl-4.0/config.5), [**CONF\_modules\_load\_file**(3)](/man/os/openssl-4.0/CONF_modules_load_file.3)

# [HISTORY](#HISTORY)

The **OPENSSL\_no\_config()** and **OPENSSL\_config()** functions were deprecated in OpenSSL 1.1.0 by **OPENSSL\_init\_crypto()**.

# [COPYRIGHT](#COPYRIGHT)

Copyright 2004-2025 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at &lt;https://www.openssl.org/source/license.html&gt;.

2026-09-29 4.0.3

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Document: OPENSSL_no_config(3ossl) from openssl-4.0 4.0.3-r4 (Chainguard OS)