X-Git-Url: https://git.openssl.org/gitweb/?a=blobdiff_plain;f=doc%2Fssl%2FSSL_CTX_new.pod;h=491ac8c172cb5e26ef8c0670c614dade058190db;hb=8aa556e1c3b49274ccae579cb584eb5b702a3b0e;hp=8b16ea3c903d2ebf6778f83142b336e499cf0bc9;hpb=14a74a21f00631f444f30846828769ab2ea59ea2;p=openssl.git diff --git a/doc/ssl/SSL_CTX_new.pod b/doc/ssl/SSL_CTX_new.pod index 8b16ea3c90..491ac8c172 100644 --- a/doc/ssl/SSL_CTX_new.pod +++ b/doc/ssl/SSL_CTX_new.pod @@ -8,7 +8,7 @@ SSL_CTX_new - create a new SSL_CTX object as framework for TLS/SSL enabled funct #include - SSL_CTX *SSL_CTX_new(SSL_METHOD *method); + SSL_CTX *SSL_CTX_new(const SSL_METHOD *method); =head1 DESCRIPTION @@ -51,22 +51,36 @@ 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. +A TLS/SSL connection established with these methods may understand the SSLv2, +SSLv3, TLSv1, TLSv1.1 and TLSv1.2 protocols. + +If the cipher list does not contain any SSLv2 ciphersuites (the default +cipher list does not) or 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. + +If any SSLv2 ciphersuites are included in the cipher list and no extensions +are required then SSLv2 compatible client hellos will be used by clients and +SSLv2 will be accepted by servers. This is B recommended due to the +insecurity of SSLv2 and the limited nature of the SSLv2 client hello +prohibiting the use of extensions. =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 or -B 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_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. 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. + +Applications which never want to support SSLv2 (even is the cipher string +is configured to use SSLv2 ciphersuites) can set SSL_OP_NO_SSLv2. SSL_CTX_new() initializes the list of ciphers, the session cache setting, -the callbacks, the keys and certificates, and the options to its default +the callbacks, the keys and certificates and the options to its default values. =head1 RETURN VALUES @@ -89,6 +103,6 @@ The return value points to an allocated SSL_CTX object. =head1 SEE ALSO L, L, -L +L, L =cut