5 SSL_CONF_cmd_value_type,
6 SSL_CONF_cmd - send configuration command
10 #include <openssl/ssl.h>
12 int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value);
13 int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd);
17 The function SSL_CONF_cmd() performs configuration operation B<cmd> with
18 optional parameter B<value> on B<ctx>. Its purpose is to simplify application
19 configuration of B<SSL_CTX> or B<SSL> structures by providing a common
20 framework for command line options or configuration files.
22 SSL_CONF_cmd_value_type() returns the type of value that B<cmd> refers to.
24 =head1 SUPPORTED COMMAND LINE COMMANDS
26 Currently supported B<cmd> names for command lines (i.e. when the
27 flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<cmd> names
28 are case sensitive. Unless otherwise stated commands can be used by
29 both clients and servers and the B<value> parameter is not used. The default
30 prefix for command line commands is B<-> and that is reflected below.
36 This sets the supported signature algorithms for TLS v1.2. For clients this
37 value is used directly for the supported signature algorithms extension. For
38 servers it is used to determine which signature algorithms to support.
40 The B<value> argument should be a colon separated list of signature algorithms
41 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
42 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
43 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
44 Note: algorithm and hash names are case sensitive.
46 If this option is not set then all signature algorithms supported by the
47 OpenSSL library are permissible.
49 =item B<-client_sigalgs>
51 This sets the supported signature algorithms associated with client
52 authentication for TLS v1.2. For servers the value is used in the supported
53 signature algorithms field of a certificate request. For clients it is
54 used to determine which signature algorithm to with the client certificate.
55 If a server does not request a certificate this option has no effect.
57 The syntax of B<value> is identical to B<-sigalgs>. If not set then
58 the value set for B<-sigalgs> will be used instead.
62 This sets the supported groups. For clients, the groups are
63 sent using the supported groups extension. For servers, it is used
64 to determine which group to use. This setting affects groups used for both
65 signatures and key exchange, if applicable. It also affects the preferred
66 key_share sent by a client in a TLSv1.3 compatible connection.
68 The B<value> argument is a colon separated list of groups. The group can be
69 either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
70 applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group
71 names are case sensitive. The list should be in order of preference with the
72 most preferred group first. The first listed group will be the one used for a
73 key_share by a TLSv1.3 client.
77 This is a synonym for the "-groups" command.
82 This sets the temporary curve used for ephemeral ECDH modes. Only used by
85 The B<value> argument is a curve name or the special value B<auto> which
86 picks an appropriate curve based on client and server preferences. The curve
87 can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
88 (e.g B<prime256v1>). Curve names are case sensitive.
92 Sets the TLSv1.2 and below ciphersuite list to B<value>. This list will be
93 combined with any configured TLSv1.3 ciphersuites. Note: syntax checking
94 of B<value> is currently not performed unless a B<SSL> or B<SSL_CTX> structure is
95 associated with B<cctx>.
97 =item B<-ciphersuites>
99 Sets the available ciphersuites for TLSv1.3 to value. This is a simple colon
100 (":") separated list of TLSv1.3 ciphersuite names in order of preference. This
101 list will be combined any configured TLSv1.2 and below ciphersuites.
106 Attempts to use the file B<value> as the certificate for the appropriate
107 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
108 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
109 structure is set. This option is only supported if certificate operations
114 Attempts to use the file B<value> as the private key for the appropriate
115 context. This option is only supported if certificate operations
116 are permitted. Note: if no B<-key> option is set then a private key is
117 not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
121 Attempts to use the file B<value> as the set of temporary DH parameters for
122 the appropriate context. This option is only supported if certificate
123 operations are permitted.
125 =item B<-record_padding>
127 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
128 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
129 B<value> must be >1 or <=16384.
131 =item B<-no_renegotiation>
133 Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting
134 B<SSL_OP_NO_RENEGOTIATION>.
136 =item B<-min_protocol>, B<-max_protocol>
138 Sets the minimum and maximum supported protocol.
139 Currently supported protocol values are B<SSLv3>, B<TLSv1>,
140 B<TLSv1.1>, B<TLSv1.2> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
141 and B<None> for no limit.
142 If the either bound is not specified then only the other bound applies,
144 To restrict the supported protocol versions use these commands rather
145 than the deprecated alternative commands below.
147 =item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3>
149 Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by
150 setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>,
151 B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3>
152 respectively. These options are deprecated, instead use B<-min_protocol> and
157 Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
161 Enables support for SSL/TLS compression, same as clearing
162 B<SSL_OP_NO_COMPRESSION>.
163 This command was introduced in OpenSSL 1.1.0.
164 As of OpenSSL 1.1.0, compression is off by default.
168 Disables support for SSL/TLS compression, same as setting
169 B<SSL_OP_NO_COMPRESSION>.
170 As of OpenSSL 1.1.0, compression is off by default.
174 Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
178 Use server and not client preference order when determining which cipher suite,
179 signature algorithm or elliptic curve to use for an incoming connection.
180 Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
182 =item B<-prioritize_chacha>
184 Prioritize ChaCha ciphers when the client has a ChaCha20 cipher at the top of
185 its preference list. This usually indicates a client without AES hardware
186 acceleration (e.g. mobile) is in use. Equivalent to B<SSL_OP_PRIORITIZE_CHACHA>.
187 Only used by servers. Requires B<-serverpref>.
189 =item B<-no_resumption_on_reneg>
191 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
193 =item B<-legacyrenegotiation>
195 permits the use of unsafe legacy renegotiation. Equivalent to setting
196 B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
198 =item B<-legacy_server_connect>, B<-no_legacy_server_connect>
200 permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
201 clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
204 =item B<-allow_no_dhe_kex>
206 In TLSv1.3 allow a non-(ec)dhe based key exchange mode on resumption. This means
207 that there will be no forward secrecy for the resumed session.
211 enables strict mode protocol handling. Equivalent to setting
212 B<SSL_CERT_FLAG_TLS_STRICT>.
214 =item B<-anti_replay>, B<-no_anti_replay>
216 Switches replay protection, on or off respectively. With replay protection on,
217 OpenSSL will automatically detect if a session ticket has been used more than
218 once, TLSv1.3 has been negotiated, and early data is enabled on the server. A
219 full handshake is forced if a session ticket is used a second or subsequent
220 time. Anti-Replay is on by default unless overridden by a configuration file and
221 is only used by servers. Anti-replay measures are required for compliance with
222 the TLSv1.3 specification. Some applications may be able to mitigate the replay
223 risks in other ways and in such cases the built-in OpenSSL functionality is not
224 required. Switching off anti-replay is equivalent to B<SSL_OP_NO_ANTI_REPLAY>.
228 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
230 Currently supported B<cmd> names for configuration files (i.e. when the
231 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
232 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
233 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
234 are also case insensitive.
236 Note: the command prefix (if set) alters the recognised B<cmd> values.
240 =item B<CipherString>
242 Sets the ciphersuite list for TLSv1.2 and below to B<value>. This list will be
243 combined with any configured TLSv1.3 ciphersuites. Note: syntax
244 checking of B<value> is currently not performed unless an B<SSL> or B<SSL_CTX>
245 structure is associated with B<cctx>.
247 =item B<Ciphersuites>
249 Sets the available ciphersuites for TLSv1.3 to B<value>. This is a simple colon
250 (":") separated list of TLSv1.3 ciphersuite names in order of preference. This
251 list will be combined any configured TLSv1.2 and below ciphersuites.
255 Attempts to use the file B<value> as the certificate for the appropriate
256 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
257 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
258 structure is set. This option is only supported if certificate operations
263 Attempts to use the file B<value> as the private key for the appropriate
264 context. This option is only supported if certificate operations
265 are permitted. Note: if no B<PrivateKey> option is set then a private key is
266 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
268 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
270 These options indicate a file or directory used for building certificate
271 chains or verifying certificate chains. These options are only supported
272 if certificate operations are permitted.
274 =item B<RequestCAFile>
276 This option indicates a file containing a set of certificates in PEM form.
277 The subject names of the certificates are sent to the peer in the
278 B<certificate_authorities> extension for TLS 1.3 (in ClientHello or
279 CertificateRequest) or in a certificate request for previous versions or
282 =item B<ServerInfoFile>
284 Attempts to use the file B<value> in the "serverinfo" extension using the
285 function SSL_CTX_use_serverinfo_file.
287 =item B<DHParameters>
289 Attempts to use the file B<value> as the set of temporary DH parameters for
290 the appropriate context. This option is only supported if certificate
291 operations are permitted.
293 =item B<RecordPadding>
295 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
296 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
297 B<value> must be >1 or <=16384.
299 =item B<NoRenegotiation>
301 Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting
302 B<SSL_OP_NO_RENEGOTIATION>.
304 =item B<SignatureAlgorithms>
306 This sets the supported signature algorithms for TLS v1.2. For clients this
307 value is used directly for the supported signature algorithms extension. For
308 servers it is used to determine which signature algorithms to support.
310 The B<value> argument should be a colon separated list of signature algorithms
311 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
312 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
313 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
314 Note: algorithm and hash names are case sensitive.
316 If this option is not set then all signature algorithms supported by the
317 OpenSSL library are permissible.
319 =item B<ClientSignatureAlgorithms>
321 This sets the supported signature algorithms associated with client
322 authentication for TLS v1.2. For servers the value is used in the supported
323 signature algorithms field of a certificate request. For clients it is
324 used to determine which signature algorithm to with the client certificate.
326 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
327 the value set for B<SignatureAlgorithms> will be used instead.
331 This sets the supported groups. For clients, the groups are
332 sent using the supported groups extension. For servers, it is used
333 to determine which group to use. This setting affects groups used for both
334 signatures and key exchange, if applicable. It also affects the preferred
335 key_share sent by a client in a TLSv1.3 compatible connection.
337 The B<value> argument is a colon separated list of groups. The group can be
338 either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
339 applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group
340 names are case sensitive. The list should be in order of preference with the
341 most preferred group first. The first listed group will be the one used for a
342 key_share by a TLSv1.3 client.
346 This is a synonym for the "Groups" command.
350 This sets the minimum supported SSL, TLS or DTLS version.
352 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
353 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
354 The value B<None> will disable the limit.
358 This sets the maximum supported SSL, TLS or DTLS version.
360 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
361 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
362 The value B<None> will disable the limit.
366 This can be used to enable or disable certain versions of the SSL,
367 TLS or DTLS protocol.
369 The B<value> argument is a comma separated list of supported protocols
370 to enable or disable.
371 If a protocol is preceded by B<-> that version is disabled.
373 All protocol versions are enabled by default.
374 You need to disable at least one protocol version for this setting have any
376 Only enabling some protocol versions does not disable the other protocol
379 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
380 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
381 The special value B<ALL> refers to all supported versions.
383 This can't enable protocols that are disabled using B<MinProtocol>
384 or B<MaxProtocol>, but can disable protocols that are still allowed
387 The B<Protocol> command is fragile and deprecated; do not use it.
388 Use B<MinProtocol> and B<MaxProtocol> instead.
389 If you do use B<Protocol>, make sure that the resulting range of enabled
390 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
391 sure to also leave TLS 1.1 enabled.
395 The B<value> argument is a comma separated list of various flags to set.
396 If a flag string is preceded B<-> it is disabled.
397 See the L<SSL_CTX_set_options(3)> function for more details of
400 Each option is listed below. Where an operation is enabled by default
401 the B<-flag> syntax is needed to disable it.
403 B<SessionTicket>: session ticket support, enabled by default. Inverse of
404 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
407 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
408 of B<SSL_OP_NO_COMPRESSION>.
410 B<EmptyFragments>: use empty fragments as a countermeasure against a
411 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
412 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
414 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
416 B<DHSingle>: enable single use DH keys, set by default. Inverse of
417 B<SSL_OP_DH_SINGLE>. Only used by servers.
419 B<ECDHSingle>: enable single use ECDH keys, set by default. Inverse of
420 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
422 B<ServerPreference>: use server and not client preference order when
423 determining which cipher suite, signature algorithm or elliptic curve
424 to use for an incoming connection. Equivalent to
425 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
427 B<PrioritizeChaCha>: prioritizes ChaCha ciphers when the client has a
428 ChaCha20 cipher at the top of its preference list. This usually indicates
429 a mobile client is in use. Equivalent to B<SSL_OP_PRIORITIZE_CHACHA>.
430 Only used by servers.
432 B<NoResumptionOnRenegotiation>: set
433 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
435 B<UnsafeLegacyRenegotiation>: permits the use of unsafe legacy renegotiation.
436 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
438 B<UnsafeLegacyServerConnect>: permits the use of unsafe legacy renegotiation
439 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
442 B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
443 default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
444 B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
446 B<AllowNoDHEKEX>: In TLSv1.3 allow a non-(ec)dhe based key exchange mode on
447 resumption. This means that there will be no forward secrecy for the resumed
448 session. Equivalent to B<SSL_OP_ALLOW_NO_DHE_KEX>.
450 B<MiddleboxCompat>: If set then dummy Change Cipher Spec (CCS) messages are sent
451 in TLSv1.3. This has the effect of making TLSv1.3 look more like TLSv1.2 so that
452 middleboxes that do not understand TLSv1.3 will not drop the connection. This
453 option is set by default. A future version of OpenSSL may not set this by
454 default. Equivalent to B<SSL_OP_ENABLE_MIDDLEBOX_COMPAT>.
456 B<AntiReplay>: If set then OpenSSL will automatically detect if a session ticket
457 has been used more than once, TLSv1.3 has been negotiated, and early data is
458 enabled on the server. A full handshake is forced if a session ticket is used a
459 second or subsequent time. This option is set by default and is only used by
460 servers. Anti-replay measures are required to comply with the TLSv1.3
461 specification. Some applications may be able to mitigate the replay risks in
462 other ways and in such cases the built-in OpenSSL functionality is not required.
463 Disabling anti-replay is equivalent to setting B<SSL_OP_NO_ANTI_REPLAY>.
467 The B<value> argument is a comma separated list of flags to set.
469 B<Peer> enables peer verification: for clients only.
471 B<Request> requests but does not require a certificate from the client.
474 B<Require> requests and requires a certificate from the client: an error
475 occurs if the client does not present a certificate. Servers only.
477 B<Once> requests a certificate from a client only on the initial connection:
478 not when renegotiating. Servers only.
480 B<RequestPostHandshake> configures the connection to support requests but does
481 not require a certificate from the client post-handshake. A certificate will
482 not be requested during the initial handshake. The server application must
483 provide a mechanism to request a certificate post-handshake. Servers only.
486 B<RequiresPostHandshake> configures the connection to support requests and
487 requires a certificate from the client post-handshake: an error occurs if the
488 client does not present a certificate. A certificate will not be requested
489 during the initial handshake. The server application must provide a mechanism
490 to request a certificate post-handshake. Servers only. TLSv1.3 only.
492 =item B<ClientCAFile>, B<ClientCAPath>
494 A file or directory of certificates in PEM format whose names are used as the
495 set of acceptable names for client CAs. Servers only. This option is only
496 supported if certificate operations are permitted.
500 =head1 SUPPORTED COMMAND TYPES
502 The function SSL_CONF_cmd_value_type() currently returns one of the following
507 =item B<SSL_CONF_TYPE_UNKNOWN>
509 The B<cmd> string is unrecognised, this return value can be use to flag
512 =item B<SSL_CONF_TYPE_STRING>
514 The value is a string without any specific structure.
516 =item B<SSL_CONF_TYPE_FILE>
518 The value is a file name.
520 =item B<SSL_CONF_TYPE_DIR>
522 The value is a directory name.
524 =item B<SSL_CONF_TYPE_NONE>
526 The value string is not used e.g. a command line option which doesn't take an
533 The order of operations is significant. This can be used to set either defaults
534 or values which cannot be overridden. For example if an application calls:
536 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
537 SSL_CONF_cmd(ctx, userparam, uservalue);
539 it will disable SSLv3 support by default but the user can override it. If
540 however the call sequence is:
542 SSL_CONF_cmd(ctx, userparam, uservalue);
543 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
545 SSLv3 is B<always> disabled and attempt to override this by the user are
548 By checking the return code of SSL_CONF_cmd() it is possible to query if a
549 given B<cmd> is recognised, this is useful if SSL_CONF_cmd() values are
550 mixed with additional application specific operations.
552 For example an application might call SSL_CONF_cmd() and if it returns
553 -2 (unrecognised command) continue with processing of application specific
556 Applications can also use SSL_CONF_cmd() to process command lines though the
557 utility function SSL_CONF_cmd_argv() is normally used instead. One way
558 to do this is to set the prefix to an appropriate value using
559 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
560 following argument to B<value> (which may be NULL).
562 In this case if the return value is positive then it is used to skip that
563 number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
564 returned then B<cmd> is not recognised and application specific arguments
565 can be checked instead. If -3 is returned a required argument is missing
566 and an error is indicated. If 0 is returned some other error occurred and
567 this can be reported back to the user.
569 The function SSL_CONF_cmd_value_type() can be used by applications to
570 check for the existence of a command or to perform additional syntax
571 checking or translation of the command value. For example if the return
572 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
573 pathname to an absolute pathname.
577 Set supported signature algorithms:
579 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
581 There are various ways to select the supported protocols.
583 This set the minimum protocol version to TLSv1, and so disables SSLv3.
584 This is the recommended way to disable protocols.
586 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
588 The following also disables SSLv3:
590 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
592 The following will first enable all protocols, and then disable
594 If no protocol versions were disabled before this has the same effect as
595 "-SSLv3", but if some versions were disables this will re-enable them before
598 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
602 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
603 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
605 This also only enables TLSv1.2:
607 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
609 Disable TLS session tickets:
611 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
615 SSL_CONF_cmd(ctx, "Options", "Compression");
617 Set supported curves to P-256, P-384:
619 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
623 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
624 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
625 returns the number of arguments processed. This is useful when processing
628 A return value of -2 means B<cmd> is not recognised.
630 A return value of -3 means B<cmd> is recognised and the command requires a
631 value but B<value> is NULL.
633 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
634 error occurred attempting to perform the operation: for example due to an
635 error in the syntax of B<value> in this case the error queue may provide
636 additional information.
640 L<SSL_CONF_CTX_new(3)>,
641 L<SSL_CONF_CTX_set_flags(3)>,
642 L<SSL_CONF_CTX_set1_prefix(3)>,
643 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
644 L<SSL_CONF_cmd_argv(3)>,
645 L<SSL_CTX_set_options(3)>
649 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
651 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
652 for backwards compatibility.
654 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
655 OpenSSL passing a command which didn't take an argument would return
656 B<SSL_CONF_TYPE_UNKNOWN>.
658 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
660 B<AllowNoDHEKEX> and B<PrioritizeChaCha> were added in OpenSSL 1.1.1.
664 Copyright 2012-2018 The OpenSSL Project Authors. All Rights Reserved.
666 Licensed under the OpenSSL license (the "License"). You may not use
667 this file except in compliance with the License. You can obtain a copy
668 in the file LICENSE in the source distribution or at
669 L<https://www.openssl.org/source/license.html>.