NAME
SSL_CTX_new, SSLv23_method, SSLv23_server_method, SSLv23_client_method,
TLSv1_2_method, TLSv1_2_server_method, TLSv1_2_client_method, TLSv1_1_method,
TLSv1_1_server_method, TLSv1_1_client_method, TLSv1_method,
TLSv1_server_method, TLSv1_client_method, SSLv3_method, SSLv3_server_method,
SSLv3_client_method, SSLv2_method, SSLv2_server_method, SSLv2_client_method,
DTLS_method, DTLS_server_method, DTLS_client_method, DTLSv1_2_method,
DTLSv1_2_server_method, DTLSv1_2_client_method, DTLSv1_method,
DTLSv1_server_method, DTLSv1_client_method - 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);
const SSL_METHOD *SSLv23_method(void);
const SSL_METHOD *SSLv23_server_method(void);
const SSL_METHOD *SSLv23_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 *TLSv1_1_method(void);
const SSL_METHOD *TLSv1_1_server_method(void);
const SSL_METHOD *TLSv1_1_client_method(void);
const SSL_METHOD *TLSv1_method(void);
const SSL_METHOD *TLSv1_server_method(void);
const SSL_METHOD *TLSv1_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_SSL2
const SSL_METHOD *SSLv2_method(void);
const SSL_METHOD *SSLv2_server_method(void);
const SSL_METHOD *SSLv2_client_method(void);
#endif
const SSL_METHOD *DTLS_method(void);
const SSL_METHOD *DTLS_server_method(void);
const SSL_METHOD *DTLS_client_method(void);
const SSL_METHOD *DTLSv1_2_method(void);
const SSL_METHOD *DTLSv1_2_server_method(void);
const SSL_METHOD *DTLSv1_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 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:
- SSLv23_method(), SSLv23_server_method(),
SSLv23_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 SSLv2, SSLv3, TLSv1, TLSv1.1 and TLSv1.2. Most
applications should use these method, and avoid the version specific
methods described below.
The list of protocols available can be further 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(3) or SSL_set_options(3) functions.
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 SSLv2 and SSLv3 protocols are deprecated and should generally not be
used. Applications should typically use SSL_CTX_set_options(3) in
combination with the SSL_OP_NO_SSLv3 flag to disable negotiation of
SSLv3 via the above version-flexible SSL/TLS methods. The
SSL_OP_NO_SSLv2 option is set by default, and would need to be
cleared via SSL_CTX_clear_options(3) in order to enable negotiation
of SSLv2.
- 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. A client will send out TLSv1.2
client hello messages and will also indicate that it only understand
TLSv1.2. A server will only understand TLSv1.2 client hello messages.
- 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. A client will send out TLSv1.1
client hello messages and will also indicate that it only understand
TLSv1.1. A server will only understand TLSv1.1 client hello messages.
- TLSv1_method(), TLSv1_server_method(),
TLSv1_client_method()
- 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.
- SSLv3_method(), SSLv3_server_method(),
SSLv3_client_method()
- 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. The SSLv3 protocol is
deprecated and should not be used.
- SSLv2_method(), SSLv2_server_method(),
SSLv2_client_method()
- 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. The SSLv2
protocol offers little to no security and should not be used. As of
OpenSSL 1.0.2g, EXPORT ciphers and 56-bit DES are no longer available with
SSLv2.
- DTLS_method(), DTLS_server_method(),
DTLS_client_method()
- These are the version-flexible DTLS methods.
- 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 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_set_options(3),
SSL_CTX_clear_options(3),
SSL_set_options(3),
SSL_CTX_free(3),
SSL_accept(3),
ssl(3),
SSL_set_connect_state(3)