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NAME

SSL_CTX_new, TLS_method, TLS_server_method, TLS_client_method, SSLv23_method, SSLv23_server_method, SSLv23_client_method, TLSv1_method, TLSv1_server_method, TLSv1_client_method, TLSv1_1_method, TLSv1_1_server_method, TLSv1_1_client_method, TLSv1_2_method, TLSv1_2_server_method, TLSv1_2_client_method, DTLSv1_method, DTLSv1_server_method, DTLSv1_client_method — create a new SSL_CTX object as framework for TLS/SSL enabled functions

SYNOPSIS

#include <openssl/ssl.h>

SSL_CTX *
SSL_CTX_new(const SSL_METHOD *method);

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);

const SSL_METHOD *
TLSv1_method(void);

const SSL_METHOD *
TLSv1_server_method(void);

const SSL_METHOD *
TLSv1_client_method(void);

const SSL_METHOD *
TLSv1_1_method(void);

const SSL_METHOD *
TLSv1_1_server_method(void);

const SSL_METHOD *
TLSv1_1_client_method(void);

const SSL_METHOD *
TLSv1_2_method(void);

const SSL_METHOD *
TLSv1_2_server_method(void);

const SSL_METHOD *
TLSv1_2_client_method(void);

const SSL_METHOD *
DTLSv1_method(void);

const SSL_METHOD *
DTLSv1_server_method(void);

const SSL_METHOD *
DTLSv1_client_method(void);

DESCRIPTION

SSL_CTX_new() creates a new SSL_CTX object as framework to establish TLS/SSL or DTLS enabled connections. It initializes the list of ciphers, the session cache setting, the callbacks, the keys and certificates, and the options to its default values.

The SSL_CTX object uses method as its 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 TLSv1, TLSv1.1 and TLSv1.2. 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_method(), TLSv1_server_method(), TLSv1_client_method()

A TLS/SSL connection established with these methods will only understand the TLSv1 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_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.

DTLSv1_method(), DTLSv1_server_method(), DTLSv1_client_method()

These are the version-specific methods for DTLSv1.

The list of protocols available can also be limited using the SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1, and SSL_OP_NO_TLSv1_2 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.

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(3), SSL_accept(3), SSL_CTX_free(3), SSL_CTX_set_min_proto_version(3), SSL_CTX_set_options(3), SSL_set_connect_state(3)