SSL_set_options man page on JazzOS

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SSL_CTX_set_options(3)		    OpenSSL		SSL_CTX_set_options(3)

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

	#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);

       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.

       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

       SSL_CTX_set_options() and SSL_set_options() affect the (external)
       protocol behaviour of the SSL library. The (internal) behaviour of the
       API can be changed by using the similar SSL_CTX_set_mode(3) and
       SSL_set_mode() functions.

       During a handshake, the option settings of the SSL object are 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 - 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.

	   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 mode, but as
	   mentioned above, this breaks this server so 16 bytes is the way to

       SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG, 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, 'cipher_suite'.

	   Netscape-Enterprise/2.01 ( 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.



	   As of OpenSSL 0.9.7h and 0.9.8a, this option has no effect.




	   Disables a countermeasure against a SSL 3.0/TLS 1.0 protocol
	   vulnerability affecting CBC ciphers, which cannot be handled by
	   some broken SSL implementations.  This option has no effect for
	   connections using other ciphers.

	   All of the above bug workarounds.

       It is usually safe to use SSL_OP_ALL to enable the bug workaround
       options if compatibility with somewhat broken implementations is

       The following modifying options are available:

	   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

	   Always create a new key when using temporary/ephemeral DH
	   parameters (see SSL_CTX_set_tmp_dh_callback(3)).  This option must
	   be used to prevent small subgroup attacks, when the DH parameters
	   were not generated using "strong" primes (e.g. when using DSA-
	   parameters, see dhparam(1)).	 If "strong" primes were used, it is
	   not strictly necessary to generate a new DH key during each
	   handshake but it is also recommended.  SSL_OP_SINGLE_DH_USE should
	   therefore be enabled whenever temporary/ephemeral DH parameters are

	   Always use ephemeral (temporary) RSA key when doing RSA operations
	   (see SSL_CTX_set_tmp_rsa_callback(3)).  According to the
	   specifications this is only done, when a RSA key can only be used
	   for signature operations (namely under export ciphers with
	   restricted RSA keylength). By setting this option, ephemeral RSA
	   keys are always used. This option breaks compatibility with the
	   SSL/TLS specifications and may lead to interoperability problems
	   with clients and should therefore never be used. Ciphers with EDH
	   (ephemeral Diffie-Hellman) key exchange should be used instead.

	   When choosing a cipher, use the server's preferences instead of the
	   client preferences. When not set, the SSL server will always follow
	   the clients preferences. When set, the SSLv3/TLSv1 server will
	   choose following its own preferences. Because of the different
	   protocol, for SSLv2 the server will send its list of preferences to
	   the client and the client chooses.



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


	   Do not use the SSLv2 protocol.

	   Do not use the SSLv3 protocol.

	   Do not use the TLSv1 protocol.

	   When performing renegotiation as a server, always start a new
	   session (i.e., session resumption requests are only accepted in the
	   initial handshake).	This option is not needed for clients.

	   Normally clients and servers will, where possible, transparently
	   make use of RFC4507bis tickets for stateless session resumption if
	   extension support is explicitly set when OpenSSL is compiled.

	   If this option is set this functionality is disabled and tickets
	   will not be used by clients or servers.

       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.

       ssl(3), SSL_new(3), SSL_clear(3), SSL_CTX_set_tmp_dh_callback(3),
       SSL_CTX_set_tmp_rsa_callback(3), dhparam(1)

       OpenSSL 0.9.7.

       SSL_OP_TLS_ROLLBACK_BUG has been added in OpenSSL 0.9.6 and was
       automatically enabled with SSL_OP_ALL. As of 0.9.7, it is no longer
       included in SSL_OP_ALL and must be explicitly set.

       SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS has been added in OpenSSL 0.9.6e.
       Versions up to OpenSSL 0.9.6c do not include the countermeasure that
       can be disabled with this option (in OpenSSL 0.9.6d, it was always

0.9.8k				  2007-08-23		SSL_CTX_set_options(3)

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