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


SYNOPSIS

        #include <openssl/ssl.h>

        SSL_CTX *SSL_CTX_new(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

           A client will send out SSLv2 client hello messages and
           will indicate that it also understands SSLv3 and
           TLSv1. A server will understand SSLv2, SSLv3, and
           TLSv1 client hello messages. This is the best choice
           when compatibility is a concern.

       If a generic method is used, it is necessary to explicitly
       set client or server mode with SSL_set_connect_state(3) or
       SSL_set_accept_state().

       The list of protocols available can later be limited using
       the SSL_OP_NO_SSLv2, SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1
       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 SSLv3 or TLSv1.

       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)


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