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SSL_CTX_config(3)                   OpenSSL                  SSL_CTX_config(3)

       SSL_CTX_config, SSL_config - configure SSL_CTX or SSL structure

       libcrypto, -lcrypto

        #include <openssl/ssl.h>

        int SSL_CTX_config(SSL_CTX *ctx, const char *name);
        int SSL_config(SSL *s, const char *name);

       The functions SSL_CTX_config() and SSL_config() configure an SSL_CTX or
       SSL structure using the configuration name.

       By calling SSL_CTX_config() or SSL_config() an application can perform
       many complex tasks based on the contents of the configuration file:
       greatly simplifying application configuration code. A degree of future
       proofing can also be achieved: an application can support configuration
       features in newer versions of OpenSSL automatically.

       A configuration file must have been previously loaded, for example
       using CONF_modules_load_file(). See openssl.cnf(5) for details of the
       configuration file syntax.

       SSL_CTX_config() and SSL_config() return 1 for success or 0 if an error

       If the file "config.cnf" contains the following:

        testapp = test_sect

        # list of configuration modules

        ssl_conf = ssl_sect

        server = server_section

        RSA.Certificate = server-rsa.pem
        ECDSA.Certificate = server-ecdsa.pem
        Ciphers = ALL:!RC4

       An application could call:

        if (CONF_modules_load_file("config.cnf", "testapp", 0) <= 0) {
            fprintf(stderr, "Error processing config file\n");
            goto err;

        ctx = SSL_CTX_new(TLS_server_method());

        if (SSL_CTX_config(ctx, "server") == 0) {
            fprintf(stderr, "Error configuring server.\n");
            goto err;

       In this example two certificates and the cipher list are configured
       without the need for any additional application code.

       openssl.cnf(5), SSL_CONF_cmd(3), CONF_modules_load_file(3)

       SSL_CTX_config() and SSL_config() were first added to OpenSSL 1.1.0

       Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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

1.1.1                             2018-09-17                 SSL_CTX_config(3)