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SSL_CTX_NEW(3)			    OpenSSL			SSL_CTX_NEW(3)

NAME
       TLSv1_2_method, TLSv1_2_server_method, TLSv1_2_client_method,
       SSL_CTX_new, SSL_CTX_up_ref, SSLv3_method, SSLv3_server_method,
       SSLv3_client_method, TLSv1_method, TLSv1_server_method,
       TLSv1_client_method, TLSv1_1_method, TLSv1_1_server_method,
       TLSv1_1_client_method, TLS_method, TLS_server_method,
       TLS_client_method, SSLv23_method, SSLv23_server_method,
       SSLv23_client_method, DTLS_method, DTLS_server_method,
       DTLS_client_method, DTLSv1_method, DTLSv1_server_method,
       DTLSv1_client_method, DTLSv1_2_method, DTLSv1_2_server_method,
       DTLSv1_2_client_method -	create a new SSL_CTX object as framework for
       TLS/SSL or DTLS enabled functions

SYNOPSIS
	#include <openssl/ssl.h>

	SSL_CTX	*SSL_CTX_new(const SSL_METHOD *method);
	int SSL_CTX_up_ref(SSL_CTX *ctx);

	const SSL_METHOD *TLS_method(void);
	const SSL_METHOD *TLS_server_method(void);
	const SSL_METHOD *TLS_client_method(void);

	const SSL_METHOD *SSLv23_method(void);
	const SSL_METHOD *SSLv23_server_method(void);
	const SSL_METHOD *SSLv23_client_method(void);

	#ifndef	OPENSSL_NO_SSL3_METHOD
	const SSL_METHOD *SSLv3_method(void);
	const SSL_METHOD *SSLv3_server_method(void);
	const SSL_METHOD *SSLv3_client_method(void);
	#endif

	#ifndef	OPENSSL_NO_TLS1_METHOD
	const SSL_METHOD *TLSv1_method(void);
	const SSL_METHOD *TLSv1_server_method(void);
	const SSL_METHOD *TLSv1_client_method(void);
	#endif

	#ifndef	OPENSSL_NO_TLS1_1_METHOD
	const SSL_METHOD *TLSv1_1_method(void);
	const SSL_METHOD *TLSv1_1_server_method(void);
	const SSL_METHOD *TLSv1_1_client_method(void);
	#endif

	#ifndef	OPENSSL_NO_TLS1_2_METHOD
	const SSL_METHOD *TLSv1_2_method(void);
	const SSL_METHOD *TLSv1_2_server_method(void);
	const SSL_METHOD *TLSv1_2_client_method(void);
	#endif

	const SSL_METHOD *DTLS_method(void);
	const SSL_METHOD *DTLS_server_method(void);
	const SSL_METHOD *DTLS_client_method(void);

	#ifndef	OPENSSL_NO_DTLS1_METHOD
	const SSL_METHOD *DTLSv1_method(void);
	const SSL_METHOD *DTLSv1_server_method(void);
	const SSL_METHOD *DTLSv1_client_method(void);
	#endif

	#ifndef	OPENSSL_NO_DTLS1_2_METHOD
	const SSL_METHOD *DTLSv1_2_method(void);
	const SSL_METHOD *DTLSv1_2_server_method(void);
	const SSL_METHOD *DTLSv1_2_client_method(void);
	#endif

DESCRIPTION
       SSL_CTX_new() creates a new SSL_CTX object as framework to establish
       TLS/SSL or DTLS enabled connections. An SSL_CTX object is reference
       counted.	Creating an SSL_CTX object for the first time increments the
       reference count.	Freeing	it (using SSL_CTX_free)	decrements it. When
       the reference count drops to zero, any memory or	resources allocated to
       the SSL_CTX object are freed. SSL_CTX_up_ref() increments the reference
       count for an existing SSL_CTX structure.

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:

       TLS_method(), TLS_server_method(), TLS_client_method()
	   These are the general-purpose version-flexible SSL/TLS methods.
	   The actual protocol version used will be negotiated to the highest
	   version mutually supported by the client and	the server.  The
	   supported protocols are SSLv3, TLSv1, TLSv1.1, TLSv1.2 and TLSv1.3.
	   Applications	should use these methods, and avoid the	version-
	   specific methods described below.

       SSLv23_method(),	SSLv23_server_method(),	SSLv23_client_method()
	   Use of these	functions is deprecated. They have been	replaced with
	   the above TLS_method(), TLS_server_method() and TLS_client_method()
	   respectively. New code should use those functions instead.

       TLSv1_2_method(), TLSv1_2_server_method(), TLSv1_2_client_method()
	   A TLS/SSL connection	established with these methods will only
	   understand the TLSv1.2 protocol.

       TLSv1_1_method(), TLSv1_1_server_method(), TLSv1_1_client_method()
	   A TLS/SSL connection	established with these methods will only
	   understand the TLSv1.1 protocol.

       TLSv1_method(), TLSv1_server_method(), TLSv1_client_method()
	   A TLS/SSL connection	established with these methods will only
	   understand the TLSv1	protocol.

       SSLv3_method(), SSLv3_server_method(), SSLv3_client_method()
	   A TLS/SSL connection	established with these methods will only
	   understand the SSLv3	protocol.  The SSLv3 protocol is deprecated
	   and should not be used.

       DTLS_method(), DTLS_server_method(), DTLS_client_method()
	   These are the version-flexible DTLS methods.	 Currently supported
	   protocols are DTLS 1.0 and DTLS 1.2.

       DTLSv1_2_method(), DTLSv1_2_server_method(), DTLSv1_2_client_method()
	   These are the version-specific methods for DTLSv1.2.

       DTLSv1_method(),	DTLSv1_server_method(),	DTLSv1_client_method()
	   These are the version-specific methods for DTLSv1.

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

       TLS_method(), TLS_server_method(), TLS_client_method(), DTLS_method(),
       DTLS_server_method() and	DTLS_client_method() are the version-flexible
       methods.	 All other methods only	support	one specific protocol version.
       Use the version-flexible	methods	instead	of the version specific
       methods.

       If you want to limit the	supported protocols for	the version flexible
       methods you can use SSL_CTX_set_min_proto_version(3),
       SSL_set_min_proto_version(3), SSL_CTX_set_max_proto_version(3) and
       SSL_set_max_proto_version(3) functions.	Using these functions it is
       possible	to choose e.g. TLS_server_method() and be able to negotiate
       with all	possible clients, but to only allow newer protocols like TLS
       1.0, TLS	1.1, TLS 1.2 or	TLS 1.3.

       The list	of protocols available can also	be limited using the
       SSL_OP_NO_SSLv3,	SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1, SSL_OP_NO_TLSv1_3,
       SSL_OP_NO_TLSv1_2 and SSL_OP_NO_TLSv1_3 options of the
       SSL_CTX_set_options(3) or SSL_set_options(3) functions, but this
       approach	is not recommended. Clients should avoid creating "holes" in
       the set of protocols they support. When disabling a protocol, make sure
       that you	also disable either all	previous or all	subsequent protocol
       versions.  In clients, when a protocol version is disabled without
       disabling all previous protocol versions, the effect is to also disable
       all subsequent protocol versions.

       The SSLv3 protocol is deprecated	and should generally not be used.
       Applications should typically use SSL_CTX_set_min_proto_version(3) to
       set the minimum protocol	to at least TLS1_VERSION.

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.

	   SSL_CTX_up_ref() returns 1 for success and 0	for failure.

HISTORY
       Support for SSLv2 and the corresponding SSLv2_method(),
       SSLv2_server_method() and SSLv2_client_method() functions where removed
       in OpenSSL 1.1.0.

       SSLv23_method(),	SSLv23_server_method() and SSLv23_client_method() were
       deprecated and the preferred TLS_method(), TLS_server_method() and
       TLS_client_method() functions were introduced in	OpenSSL	1.1.0.

       All version-specific methods were deprecated in OpenSSL 1.1.0.

SEE ALSO
       SSL_CTX_set_options(3), SSL_CTX_free(3),	SSL_accept(3),
       SSL_CTX_set_min_proto_version(3), ssl(7), SSL_set_connect_state(3)

COPYRIGHT
       Copyright 2000-2018 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
       <https://www.openssl.org/source/license.html>.

1.1.1a				  2018-11-20			SSL_CTX_NEW(3)

NAME | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUES | HISTORY | SEE ALSO | COPYRIGHT

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