=pod =head1 NAME SSL_CTX_new - create a new SSL_CTX object as framework for TLS/SSL enabled functions =head1 SYNOPSIS #include <openssl/ssl.h> SSL_CTX *SSL_CTX_new(SSL_METHOD *method); =head1 DESCRIPTION SSL_CTX_new() creates a new B<SSL_CTX> object as framework to establish TLS/SSL enabled connections. =head1 NOTES The SSL_CTX object uses B<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. B<method> can be of the following types: =over 4 =item 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. =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. This especially means, that it will not understand SSLv2 client hello messages which are widely used for compatibility reasons, see SSLv23_*_method(). =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. 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. =item 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. =back 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 B<SSL_CTX_set_options()> or B<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. =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 SEE ALSO L<SSL_CTX_free(3)|SSL_CTX_free(3)>, L<SSL_accept(3)|SSL_accept(3)>, L<ssl(3)|ssl(3)>, L<SSL_set_connect_state(3)|SSL_set_connect_state(3)> =cut