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SSL_CTX_new(3)                      OpenSSL                     SSL_CTX_new(3)



NAME
       SSL_CTX_new - create a new SSL_CTX object as framework for TLS/SSL
       enabled functions

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/ssl.h>

        SSL_CTX *SSL_CTX_new(const SSL_METHOD *method);

DESCRIPTION
       SSL_CTX_new() creates a new SSL_CTX object as framework to establish
       TLS/SSL enabled connections.

NOTES
       The SSL_CTX object uses method as connection method. The methods exist
       in a generic type (for client and server use), a server only type, and
       a client only type. method can be of the following types:

       SSLv2_method(void), SSLv2_server_method(void),
           SSLv2_client_method(void)
           A TLS/SSL connection established with these methods will only
           understand the SSLv2 protocol. A client will send out SSLv2 client
           hello messages and will also indicate that it only understand
           SSLv2. A server will only understand SSLv2 client hello messages.

       SSLv3_method(void), SSLv3_server_method(void),
           SSLv3_client_method(void)
           A TLS/SSL connection established with these methods will only
           understand the SSLv3 protocol. A client will send out SSLv3 client
           hello messages and will indicate that it only understands SSLv3. A
           server will only understand SSLv3 client hello messages. This
           especially means, that it will not understand SSLv2 client hello
           messages which are widely used for compatibility reasons, see
           SSLv23_*_method().

       TLSv1_method(void), TLSv1_server_method(void),
           TLSv1_client_method(void)
           A TLS/SSL connection established with these methods will only
           understand the TLSv1 protocol. A client will send out TLSv1 client
           hello messages and will indicate that it only understands TLSv1. A
           server will only understand TLSv1 client hello messages. This
           especially means, that it will not understand SSLv2 client hello
           messages which are widely used for compatibility reasons, see
           SSLv23_*_method(). It will also not understand SSLv3 client hello
           messages.

       SSLv23_method(void), SSLv23_server_method(void),
           SSLv23_client_method(void)
           A TLS/SSL connection established with these methods may understand
           the SSLv2, SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols.

           If the cipher list does not contain any SSLv2 ciphersuites (the
           default cipher list does not) or extensions are required (for
           example server name) a client will send out TLSv1 client hello
           messages including extensions and will indicate that it also
           understands TLSv1.1, TLSv1.2 and permits a fallback to SSLv3. A
           server will support SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols.
           This is the best choice when compatibility is a concern.

           If any SSLv2 ciphersuites are included in the cipher list and no
           extensions are required then SSLv2 compatible client hellos will be
           used by clients and SSLv2 will be accepted by servers. This is not
           recommended due to the insecurity of SSLv2 and the limited nature
           of the SSLv2 client hello prohibiting the use of extensions.

       The list of protocols available can later be limited using the
       SSL_OP_NO_SSLv2, SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1
       and SSL_OP_NO_TLSv1_2 options of the SSL_CTX_set_options() or
       SSL_set_options() functions.  Using these options it is possible to
       choose e.g. SSLv23_server_method() and be able to negotiate with all
       possible clients, but to only allow newer protocols like TLSv1, TLSv1.1
       or TLS v1.2.

       Applications which never want to support SSLv2 (even is the cipher
       string is configured to use SSLv2 ciphersuites) can set
       SSL_OP_NO_SSLv2.

       SSL_CTX_new() initializes the list of ciphers, the session cache
       setting, the callbacks, the keys and certificates and the options to
       its default values.

RETURN VALUES
       The following return values can occur:

       NULL
           The creation of a new SSL_CTX object failed. Check the error stack
           to find out the reason.

       Pointer to an SSL_CTX object
           The return value points to an allocated SSL_CTX object.

SEE ALSO
       SSL_CTX_free(3), SSL_accept(3), ssl(3),  SSL_set_connect_state(3)



1.0.1i                            2014-08-10                    SSL_CTX_new(3)