=pod =head1 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, TLS_method, TLS_server_method, TLS_client_method, SSLv23_method, SSLv23_server_method, SSLv23_client_method - create a new SSL_CTX object as framework for TLS/SSL enabled functions =head1 SYNOPSIS #include SSL_CTX *SSL_CTX_new(const SSL_METHOD *method); =head1 DESCRIPTION SSL_CTX_new() creates a new B object as framework to establish TLS/SSL enabled connections. =head1 NOTES The SSL_CTX object uses B as connection method. The methods exist in a generic type (for client and server use), a server only type, and a client only type. B can be of the following types: =over 4 =item 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. =item 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. =item TLSv1_1_method(void), TLSv1_1_server_method(void), TLSv1_1_client_method(void) A TLS/SSL connection established with these methods will only understand the TLSv1.1 protocol. A client will send out TLSv1.1 client hello messages and will indicate that it only understands TLSv1.1. A server will only understand TLSv1.1 client hello messages. =item TLSv1_2_method(void), TLSv1_2_server_method(void), TLSv1_2_client_method(void) A TLS/SSL connection established with these methods will only understand the TLSv1.2 protocol. A client will send out TLSv1.2 client hello messages and will indicate that it only understands TLSv1.2. A server will only understand TLSv1.2 client hello messages. =item TLS_method(void), TLS_server_method(void), TLS_client_method(void) A TLS/SSL connection established with these methods may understand the SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols. If extensions are required (for example server name) 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. =item SSLv23_method(void), SSLv23_server_method(void), SSLv23_client_method(void) Use of these functions is deprecated. They have been replaced with TLS_Method(), TLS_server_method() and TLS_client_method() respectively. New code should use those functions instead. =back 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 e.g. TLS_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. Applications which never want to support SSLv3 can set SSL_OP_NO_SSLv3. 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. =head1 RETURN VALUES The following return values can occur: =over 4 =item NULL The creation of a new SSL_CTX object failed. Check the error stack to find out the reason. =item Pointer to an SSL_CTX object The return value points to an allocated SSL_CTX object. =back =head1 HISTORY SSLv2_method, SSLv2_server_method and SSLv2_client_method where removed in OpenSSL 1.1.0. SSLv23_method, SSLv23_server_method and SSLv23_client_method were deprecated and TLS_method, TLS_server_method and TLS_client_method were introduced in OpenSSL 1.1.0. =head1 SEE ALSO L, L, L, L =cut