5 SSL_CTX_new, SSL_CTX_up_ref, SSLv3_method, SSLv3_server_method,
6 SSLv3_client_method, TLSv1_method, TLSv1_server_method, TLSv1_client_method,
7 TLSv1_1_method, TLSv1_1_server_method, TLSv1_1_client_method, TLS_method,
8 TLS_server_method, TLS_client_method, SSLv23_method, SSLv23_server_method,
9 SSLv23_client_method, DTLS_method, DTLS_server_method, DTLS_client_method,
10 DTLSv1_method, DTLSv1_server_method, DTLSv1_client_method,
11 DTLSv1_2_method, DTLSv1_2_server_method, DTLSv1_2_client_method -
12 create a new SSL_CTX object as framework for TLS/SSL or DTLS enabled
17 #include <openssl/ssl.h>
19 SSL_CTX *SSL_CTX_new(const SSL_METHOD *method);
20 void SSL_CTX_up_ref(SSL_CTX *ctx);
22 const SSL_METHOD *TLS_method(void);
23 const SSL_METHOD *TLS_server_method(void);
24 const SSL_METHOD *TLS_client_method(void);
26 #define SSLv23_method TLS_method
27 #define SSLv23_server_method TLS_server_method
28 #define SSLv23_client_method TLS_client_method
30 #ifndef OPENSSL_NO_SSL3_METHOD
31 const SSL_METHOD *SSLv3_method(void);
32 const SSL_METHOD *SSLv3_server_method(void);
33 const SSL_METHOD *SSLv3_client_method(void);
36 const SSL_METHOD *TLSv1_method(void);
37 const SSL_METHOD *TLSv1_server_method(void);
38 const SSL_METHOD *TLSv1_client_method(void);
40 const SSL_METHOD *TLSv1_1_method(void);
41 const SSL_METHOD *TLSv1_1_server_method(void);
42 const SSL_METHOD *TLSv1_1_client_method(void);
44 const SSL_METHOD *TLSv1_2_method(void);
45 const SSL_METHOD *TLSv1_2_server_method(void);
46 const SSL_METHOD *TLSv1_2_client_method(void);
48 const SSL_METHOD *DTLS_method(void);
49 const SSL_METHOD *DTLS_server_method(void);
50 const SSL_METHOD *DTLS_client_method(void);
52 const SSL_METHOD *DTLSv1_method(void);
53 const SSL_METHOD *DTLSv1_server_method(void);
54 const SSL_METHOD *DTLSv1_client_method(void);
56 const SSL_METHOD *DTLSv1_2_method(void);
57 const SSL_METHOD *DTLSv1_2_server_method(void);
58 const SSL_METHOD *DTLSv1_2_client_method(void);
62 SSL_CTX_new() creates a new B<SSL_CTX> object as framework to
63 establish TLS/SSL or DTLS enabled connections. An B<SSL_CTX> object is
64 reference counted. Creating an B<SSL_CTX> object for the first time increments
65 the reference count. Freeing it (using SSL_CTX_free) decrements it. When the
66 reference count drops to zero, any memory or resources allocated to the
67 B<SSL_CTX> object are freed. SSL_CTX_up_ref() increments the reference count for
68 an existing B<SSL_CTX> structure.
72 The SSL_CTX object uses B<method> as connection method.
73 The methods exist in a generic type (for client and server use), a server only
74 type, and a client only type.
75 B<method> can be of the following types:
79 =item SSLv3_method(), SSLv3_server_method(), SSLv3_client_method()
81 An SSL connection established with these methods will only understand
83 A client will send out a SSLv3 client hello messages and will
84 indicate that it supports SSLv3.
85 A server will only understand SSLv3 client hello message and only
86 support the SSLv3 protocol.
88 =item TLSv1_method(), TLSv1_server_method(), TLSv1_client_method()
90 A TLS connection established with these methods will only understand
93 =item TLSv1_1_method(), TLSv1_1_server_method(), TLSv1_1_client_method()
95 A TLS connection established with these methods will only understand
98 =item TLSv1_2_method(), TLSv1_2_server_method(), TLSv1_2_client_method()
100 A TLS connection established with these methods will only understand
101 the TLS 1.2 protocol.
103 =item TLS_method(), TLS_server_method(), TLS_client_method()
105 A TLS/SSL connection established with these methods may understand
106 the SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols.
108 If extensions are required (for example server name)
109 a client will send out TLSv1 client hello messages including extensions and
110 will indicate that it also understands TLSv1.1, TLSv1.2 and permits a
111 fallback to SSLv3. A server will support SSLv3, TLSv1, TLSv1.1 and TLSv1.2
112 protocols. This is the best choice when compatibility is a concern.
114 =item SSLv23_method(), SSLv23_server_method(), SSLv23_client_method()
116 Use of these functions is deprecated. They have been replaced with TLS_method(),
117 TLS_server_method() and TLS_client_method() respectively. New code should use
118 those functions instead.
120 =item DTLS_method(), DTLS_server_method(), DTLS_client_method()
122 A DTLS connection established with those methods understands all
123 supported DTLS protocols.
124 Currently supported protocols are DTLS 1.0 and DTLS 1.2.
126 =item DTLSv1_method(), DTLSv1_server_method(), DTLSv1_client_method()
128 A DTLS connection established with these methods will only understand
129 the DTLS 1.0 protocol.
131 =item DTLSv1_2_method(), DTLSv1_2_server_method(), DTLSv1_2_client_method()
133 A DTLS connection established with these methods will only understand
134 the DTLS 1.2 protocol.
138 TLS_method(), TLS_server_method(), TLS_client_method(), DTLS_method(),
139 DTLS_server_method() and DTLS_client_method() are the version
141 All other methods only support one specific protocol version.
142 Use these methods instead of the other version specific methods.
144 If you want to limit the supported protocols for the version flexible
145 methods you can use SSL_CTX_set_min_proto_version(),
146 SSL_set_min_proto_version(), SSL_CTX_set_max_proto_version() and
147 SSL_set_max_proto_version() functions.
148 They can also be limited by setting an option like B<SSL_OP_NO_SSLv3>
149 via the L<SSL_CTX_set_options(3)> or L<SSL_set_options(3)> functions,
150 but that's not recommended.
151 Using these functions it is possible to choose e.g. TLS_server_method()
152 and be able to negotiate with all possible clients, but to only
153 allow newer protocols like TLS 1.0, TLS 1.1 or TLS 1.2.
155 SSL_CTX_new() initializes the list of ciphers, the session cache
156 setting, the callbacks, the keys and certificates and the options
157 to its default values.
161 The following return values can occur:
167 The creation of a new SSL_CTX object failed. Check the error stack to
170 =item Pointer to an SSL_CTX object
172 The return value points to an allocated SSL_CTX object.
178 Support for SSLv2 and the corresponding SSLv2_method(),
179 SSLv2_server_method() and SSLv2_client_method() functions where
180 removed in OpenSSL 1.1.0.
182 SSLv23_method(), SSLv23_server_method() and SSLv23_client_method()
183 were deprecated and the preferred TLS_method(), TLS_server_method()
184 and TLS_client_method() functions were introduced in OpenSSL 1.1.0.
188 L<SSL_CTX_free(3)>, L<SSL_accept(3)>,
189 L<SSL_CTX_set_min_proto_version(3)>,
190 L<ssl(3)>, L<SSL_set_connect_state(3)>