SSL_CTX_NEW(3) BSD Library Functions Manual SSL_CTX_NEW(3)NAME
SSL_CTX_new, 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, SSLv23_method,
SSLv23_server_method, SSLv23_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);
DESCRIPTIONSSL_CTX_new() creates a new SSL_CTX object as framework to establish
TLS/SSL enabled connections.
NOTES
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:
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 mes‐
sages. Importantly, this 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 mes‐
sages. Importantly, this 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 may under‐
stand the SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols.
A client will send out TLSv1 client hello messages including
extensions and will indicate that it also understands TLSv1.1,
TLSv1.2 and permits a fallback to SSLv3. A server will support
SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols. This is the best
choice when compatibility is a concern.
The list of protocols available can later be limited using the
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() or
SSL_set_options() functions. Using these options it is possible to
choose, for example, SSLv23_server_method() and be able to negotiate with
all possible clients, but to only allow newer protocols like TLSv1,
TLSv1.1 or TLS v1.2.
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 ALSOssl(3), SSL_accept(3), SSL_CTX_free(3), SSL_set_connect_state(3)BSD April 24, 2024 BSD
