SSL_CTX_set_options, SSL_set_options, SSL_CTX_get_options,
       SSL_get_options - manipulate SSL engine options


SYNOPSIS

        #include <openssl/ssl.h>

        long SSL_CTX_set_options(SSL_CTX *ctx, long options);
        long SSL_set_options(SSL *ssl, long options);

        long SSL_CTX_get_options(SSL_CTX *ctx);
        long SSL_get_options(SSL *ssl);


DESCRIPTION

       SSL_CTX_set_options() adds the options set via bitmask in
       options to ctx.  Options already set before are not
       cleared.

       SSL_set_options() adds the options set via bitmask in
       options to ssl.  Options already set before are not
       cleared.

       SSL_CTX_get_options() returns the options set for ctx.

       SSL_get_options() returns the options set for ssl.


NOTES

       The behaviour of the SSL library can be changed by setting
       several options.  The options are coded as bitmasks and
       can be combined by a logical or operation (|). Options can
       only be added but can never be reset.

       During a handshake, the option settings of the SSL object
       used. When a new SSL object is created from a context
       using SSL_new(), the current option setting is copied.
       Changes to ctx do not affect already created SSL objects.
       SSL_clear() does not affect the settings.

       The following bug workaround options are available:

       SSL_OP_MICROSOFT_SESS_ID_BUG
           www.microsoft.com - when talking SSLv2, if session-id
           reuse is performed, the session-id passed back in the
           server-finished message is different from the one
           decided upon.

       SSL_OP_NETSCAPE_CHALLENGE_BUG
           Netscape-Commerce/1.12, when talking SSLv2, accepts a
           32 byte challenge but then appears to only use 16
           bytes when generating the encryption keys.  Using 16
           bytes is ok but it should be ok to use 32.  According
           to the SSLv3 spec, one should use 32 bytes for the
           challenge when operating in SSLv2/v3 compatibility

           so 16 bytes is the way to go.

       SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
           ssl3.netscape.com:443, first a connection is
           established with RC4-MD5.  If it is then resumed, we
           end up using DES-CBC3-SHA.  It should be RC4-MD5
           according to 7.6.1.3, 'cipher_suite'.

           Netscape-Enterprise/2.01
           (https://merchant.netscape.com) has this bug.  It only
           really shows up when connecting via SSLv2/v3 then
           reconnecting via SSLv3. The cipher list changes....

           NEW INFORMATION.  Try connecting with a cipher list of
           just DES-CBC-SHA:RC4-MD5.  For some weird reason, each
           new connection uses RC4-MD5, but a re-connect tries to
           use DES-CBC-SHA.  So netscape, when doing a re-
           connect, always takes the first cipher in the cipher
           list.

       SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
           ...

       SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
           ...

       SSL_OP_MSIE_SSLV2_RSA_PADDING
           ...

       SSL_OP_SSLEAY_080_CLIENT_DH_BUG
           ...

       SSL_OP_TLS_D5_BUG
           ...

       SSL_OP_TLS_BLOCK_PADDING_BUG
           ...

       SSL_OP_TLS_ROLLBACK_BUG
           Disable version rollback attack detection.

           During the client key exchange, the client must send
           the same information about acceptable SSL/TLS protocol
           levels as during the first hello. Some clients violate
           this rule by adapting to the server's answer.
           (Example: the client sends a SSLv2 hello and accepts
           up to SSLv3.1=TLSv1, the server only understands up to
           SSLv3. In this case the client must still use the same
           SSLv3.1=TLSv1 announcement. Some clients step down to
           SSLv3 with respect to the server's answer and violate
           the version rollback protection.)

           All of the above bug workarounds.

       It is save and recommended to use SSL_OP_ALL to enable the
       bug workaround options.

       The following modifying options are available:

       SSL_OP_SINGLE_DH_USE
           Always create a new key when using temporary DH
           parameters.

       SSL_OP_EPHEMERAL_RSA
           Also use the temporary RSA key when doing RSA
           operations.

       SSL_OP_PKCS1_CHECK_1
           ...

       SSL_OP_PKCS1_CHECK_2
           ...

       SSL_OP_NETSCAPE_CA_DN_BUG
           If we accept a netscape connection, demand a client
           cert, have a non-self-sighed CA which does not have
           it's CA in netscape, and the browser has a cert, it
           will crash/hang.  Works for 3.x and 4.xbeta

       SSL_OP_NON_EXPORT_FIRST
           On servers try to use non-export (stronger) ciphers
           first. This option does not work under all
           circumstances (in the code it is declared "broken").

       SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG
           ...

       SSL_OP_NO_SSLv2
           Do not use the SSLv2 protocol.

       SSL_OP_NO_SSLv3
           Do not use the SSLv3 protocol.

       SSL_OP_NO_TLSv1
           Do not use the TLSv1 protocol.


RETURN VALUES

       SSL_CTX_set_options() and SSL_set_options() return the new
       options bitmask after adding options.

       SSL_CTX_get_options() and SSL_get_options() return the
       current bitmask.


SEE ALSO

       ssl(3), SSL_new(3), SSL_clear(3)

       SSL_OP_TLS_ROLLBACK_BUG has been added in OpenSSL 0.9.6.


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