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_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.
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)
