5 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
9 #include <openssl/ssl.h>
11 SSL_CTX *SSL_CTX_new(const SSL_METHOD *method);
15 SSL_CTX_new() creates a new B<SSL_CTX> object as framework to establish
16 TLS/SSL enabled connections.
20 The SSL_CTX object uses B<method> as connection method. The methods exist
21 in a generic type (for client and server use), a server only type, and a
22 client only type. B<method> can be of the following types:
26 =item SSLv3_method(void), SSLv3_server_method(void), SSLv3_client_method(void)
28 A TLS/SSL connection established with these methods will only understand the
29 SSLv3 protocol. A client will send out SSLv3 client hello messages
30 and will indicate that it only understands SSLv3. A server will only understand
31 SSLv3 client hello messages. This especially means, that it will
32 not understand SSLv2 client hello messages which are widely used for
33 compatibility reasons, see SSLv23_*_method().
35 =item TLSv1_method(void), TLSv1_server_method(void), TLSv1_client_method(void)
37 A TLS/SSL connection established with these methods will only understand the
38 TLSv1 protocol. A client will send out TLSv1 client hello messages
39 and will indicate that it only understands TLSv1. A server will only understand
40 TLSv1 client hello messages. This especially means, that it will
41 not understand SSLv2 client hello messages which are widely used for
42 compatibility reasons, see SSLv23_*_method(). It will also not understand
43 SSLv3 client hello messages.
45 =item TLSv1_1_method(void), TLSv1_1_server_method(void), TLSv1_1_client_method(void)
47 A TLS/SSL connection established with these methods will only understand the
48 TLSv1.1 protocol. A client will send out TLSv1.1 client hello messages
49 and will indicate that it only understands TLSv1.1. A server will only
50 understand TLSv1.1 client hello messages. This especially means, that it will
51 not understand SSLv2 client hello messages which are widely used for
52 compatibility reasons, see SSLv23_*_method(). It will also not understand
53 SSLv3 client hello messages.
55 =item SSLv23_method(void), SSLv23_server_method(void), SSLv23_client_method(void)
57 A TLS/SSL connection established with these methods may understand the
58 SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols.
60 If extensions are required (for example server name)
61 a client will send out TLSv1 client hello messages including extensions and
62 will indicate that it also understands TLSv1.1, TLSv1.2 and permits a
63 fallback to SSLv3. A server will support SSLv3, TLSv1, TLSv1.1 and TLSv1.2
64 protocols. This is the best choice when compatibility is a concern.
68 The list of protocols available can later be limited using the
69 SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1 and SSL_OP_NO_TLSv1_2
70 options of the SSL_CTX_set_options() or SSL_set_options() functions.
71 Using these options it is possible to choose e.g. SSLv23_server_method() and
72 be able to negotiate with all possible clients, but to only allow newer
73 protocols like TLSv1, TLSv1.1 or TLS v1.2.
75 Applications which never want to support SSLv3 can set SSL_OP_NO_SSLv3.
77 SSL_CTX_new() initializes the list of ciphers, the session cache setting,
78 the callbacks, the keys and certificates and the options to its default
83 The following return values can occur:
89 The creation of a new SSL_CTX object failed. Check the error stack to
92 =item Pointer to an SSL_CTX object
94 The return value points to an allocated SSL_CTX object.
100 SSLv2_method, SSLv2_server_method and SSLv2_client_method where removed in
105 L<SSL_CTX_free(3)|SSL_CTX_free(3)>, L<SSL_accept(3)|SSL_accept(3)>,
106 L<ssl(3)|ssl(3)>, L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>