SSL_CTX_new(3)

     SSL_CTX_new(3)         0.9.6h (2001-07-25)         SSL_CTX_new(3)

     NAME
          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_client_method(void)
          SSLv2_method(void), SSLv2_server_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_client_method(void)
          SSLv3_method(void), SSLv3_server_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_client_method(void)
          TLSv1_method(void), TLSv1_server_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_client_method(void)
          SSLv23_method(void), SSLv23_server_method(void),

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     SSL_CTX_new(3)         0.9.6h (2001-07-25)         SSL_CTX_new(3)

              A TLS/SSL connection established with these methods will
              understand the SSLv2, SSLv3, and TLSv1 protocol. 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.

          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 SSSSLL_CCTTXX_sseett_ooppttiioonnss(()) or SSSSLL_sseett_ooppttiioonnss(())
          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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