SSL_CTX_new - create a new SSL_CTX object as framework for
TLS/SSL enabled functions
libcrypto, -lcrypto
#include <openssl/ssl.h>
SSL_CTX *SSL_CTX_new(SSL_METHOD *method);
SSL_CTX_new() creates a new SSL_CTX object as framework to
establish TLS/SSL enabled connections.
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
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 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.
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_free(3), SSL_accept(3), ssl(3), SSL_set_connect_state(3)
2002-06-10 0.9.6g SSL_CTX_new(3)
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