Sortix nightly manual
This manual documents Sortix nightly, a development build that has not been officially released. You can instead view this document in the latest official manual.
|SSL_CTX_SET_OPTIONS(3)||Library Functions Manual||SSL_CTX_SET_OPTIONS(3)|
manipulate SSL options
SSL_CTX_set_options(SSL_CTX *ctx, long options); long
SSL_set_options(SSL *ssl, long options); long
SSL_CTX_clear_options(SSL_CTX *ctx, long options); long
SSL_clear_options(SSL *ssl, long options); long
SSL_CTX_get_options(SSL_CTX *ctx); long
SSL_get_options(SSL *ssl); long
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_clear_options() clears the options set via bitmask in options to ctx.
SSL_clear_options() clears the options set via bitmask in options to ssl.
SSL_CTX_get_options() returns the options set for ctx.
SSL_get_options() returns the options set for ssl.
SSL_get_secure_renegotiation_support() indicates whether the peer supports secure renegotiation. All these functions are implemented using macros. 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 bitwise OR operation (|).
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(3) 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(3), 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:
- Disables a countermeasure against a 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.
- This is currently an alias for
SSL_OP_ALLto enable the bug workaround options if compatibility with somewhat broken implementations is desired. The following modifying options are available:
- When choosing a cipher, use the server's preferences instead of the client preferences. When not set, the server will always follow the client's preferences. When set, the server will choose following its own preferences.
- Turn on Cookie Exchange as described in RFC 4347 Section 4.2.1. Only affects DTLS connections.
- Allow legacy insecure renegotiation between OpenSSL and unpatched servers only: this option is currently set by default. See the SECURE RENEGOTIATION section for more details.
- Do not use the DTLSv1 protocol. Deprecated; use SSL_CTX_set_min_proto_version(3) instead.
- Do not use the DTLSv1.2 protocol. Deprecated; use SSL_CTX_set_min_proto_version(3) instead.
- Do not query the MTU. Only affects DTLS connections.
- 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 using TLSv1.2 and earlier will, where possible, transparently make use of RFC 5077 tickets for stateless session resumption. If this option is set, this functionality is disabled and tickets will not be used by clients or servers.
- Do not use the TLSv1.0 protocol. Deprecated; use SSL_CTX_set_min_proto_version(3) instead.
- Do not use the TLSv1.1 protocol. Deprecated; use SSL_CTX_set_min_proto_version(3) instead.
- Do not use the TLSv1.2 protocol. Deprecated; use SSL_CTX_set_max_proto_version(3) instead.
SSL_OP_LEGACY_SERVER_CONNECTis set then initial connections and renegotiation between patched OpenSSL clients and unpatched servers succeeds. If neither option is set then initial connections to unpatched servers will fail. The option
SSL_OP_LEGACY_SERVER_CONNECTis currently set by default even though it has security implications: otherwise it would be impossible to connect to unpatched servers (i.e., all of them initially) and this is clearly not acceptable. Renegotiation is permitted because this does not add any additional security issues: during an attack clients do not see any renegotiations anyway. As more servers become patched, the option
SSL_OP_LEGACY_SERVER_CONNECTwill not be set by default in a future version of OpenSSL. OpenSSL client applications wishing to ensure they can connect to unpatched servers should always set
SSL_OP_LEGACY_SERVER_CONNECT. OpenSSL client applications that want to ensure they can not connect to unpatched servers (and thus avoid any security issues) should always clear
SSL_set_options() return the new options bitmask after adding options.
SSL_clear_options() return the new options bitmask after clearing options.
SSL_get_options() return the current bitmask.
SSL_get_secure_renegotiation_support() returns 1 is the peer supports secure renegotiation and 0 if it does not. openssl(1), ssl(3), SSL_clear(3), SSL_CTX_ctrl(3), SSL_CTX_set_min_proto_version(3), SSL_new(3)
SSL_set_options() first appeared in SSLeay 0.9.0 and have been available since OpenBSD 2.4.
SSL_get_options() first appeared in OpenSSL 0.9.2b and have been available since OpenBSD 2.6.
SSL_get_secure_renegotiation_support() first appeared in OpenSSL 0.9.8m and have been available since OpenBSD 4.9.
|March 31, 2022||Debian|