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 cipher suite list to B<value>. Note: syntax checking of B<value> is
93 currently not performed unless a B<SSL> or B<SSL_CTX> structure is
94 associated with B<cctx>.
98 Attempts to use the file B<value> as the certificate for the appropriate
99 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
100 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
101 structure is set. This option is only supported if certificate operations
106 Attempts to use the file B<value> as the private key for the appropriate
107 context. This option is only supported if certificate operations
108 are permitted. Note: if no B<-key> option is set then a private key is
109 not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
113 Attempts to use the file B<value> as the set of temporary DH parameters for
114 the appropriate context. This option is only supported if certificate
115 operations are permitted.
117 =item B<-record_padding>
119 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
120 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
121 B<value> must be >1 or <=16384.
123 =item B<-no_renegotiation>
125 Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting
126 B<SSL_OP_NO_RENEGOTIATION>.
128 =item B<-min_protocol>, B<-max_protocol>
130 Sets the minimum and maximum supported protocol.
131 Currently supported protocol values are B<SSLv3>, B<TLSv1>,
132 B<TLSv1.1>, B<TLSv1.2> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
133 and B<None> for no limit.
134 If the either bound is not specified then only the other bound applies,
136 To restrict the supported protocol versions use these commands rather
137 than the deprecated alternative commands below.
139 =item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3>
141 Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by
142 setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>,
143 B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3>
144 respectively. These options are deprecated, instead use B<-min_protocol> and
149 Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
153 Enables support for SSL/TLS compression, same as clearing
154 B<SSL_OP_NO_COMPRESSION>.
155 This command was introduced in OpenSSL 1.1.0.
156 As of OpenSSL 1.1.0, compression is off by default.
160 Disables support for SSL/TLS compression, same as setting
161 B<SSL_OP_NO_COMPRESSION>.
162 As of OpenSSL 1.1.0, compression is off by default.
166 Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
170 Use server and not client preference order when determining which cipher suite,
171 signature algorithm or elliptic curve to use for an incoming connection.
172 Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
174 =item B<-no_resumption_on_reneg>
176 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
178 =item B<-legacyrenegotiation>
180 permits the use of unsafe legacy renegotiation. Equivalent to setting
181 B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
183 =item B<-legacy_server_connect>, B<-no_legacy_server_connect>
185 permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
186 clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
191 enables strict mode protocol handling. Equivalent to setting
192 B<SSL_CERT_FLAG_TLS_STRICT>.
196 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
198 Currently supported B<cmd> names for configuration files (i.e. when the
199 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
200 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
201 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
202 are also case insensitive.
204 Note: the command prefix (if set) alters the recognised B<cmd> values.
208 =item B<CipherString>
210 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
211 currently not performed unless an B<SSL> or B<SSL_CTX> structure is
212 associated with B<cctx>.
216 Attempts to use the file B<value> as the certificate for the appropriate
217 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
218 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
219 structure is set. This option is only supported if certificate operations
224 Attempts to use the file B<value> as the private key for the appropriate
225 context. This option is only supported if certificate operations
226 are permitted. Note: if no B<PrivateKey> option is set then a private key is
227 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
229 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
231 These options indicate a file or directory used for building certificate
232 chains or verifying certificate chains. These options are only supported
233 if certificate operations are permitted.
235 =item B<RequestCAFile>
237 This option indicates a file containing a set of certificates in PEM form.
238 The subject names of the certificates are sent to the peer in the
239 B<certificate_authorities> extension for TLS 1.3 (in ClientHello or
240 CertificateRequest) or in a certificate request for previous versions or
243 =item B<ServerInfoFile>
245 Attempts to use the file B<value> in the "serverinfo" extension using the
246 function SSL_CTX_use_serverinfo_file.
248 =item B<DHParameters>
250 Attempts to use the file B<value> as the set of temporary DH parameters for
251 the appropriate context. This option is only supported if certificate
252 operations are permitted.
254 =item B<RecordPadding>
256 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
257 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
258 B<value> must be >1 or <=16384.
260 =item B<NoRenegotiation>
262 Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting
263 B<SSL_OP_NO_RENEGOTIATION>.
265 =item B<SignatureAlgorithms>
267 This sets the supported signature algorithms for TLS v1.2. For clients this
268 value is used directly for the supported signature algorithms extension. For
269 servers it is used to determine which signature algorithms to support.
271 The B<value> argument should be a colon separated list of signature algorithms
272 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
273 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
274 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
275 Note: algorithm and hash names are case sensitive.
277 If this option is not set then all signature algorithms supported by the
278 OpenSSL library are permissible.
280 =item B<ClientSignatureAlgorithms>
282 This sets the supported signature algorithms associated with client
283 authentication for TLS v1.2. For servers the value is used in the supported
284 signature algorithms field of a certificate request. For clients it is
285 used to determine which signature algorithm to with the client certificate.
287 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
288 the value set for B<SignatureAlgorithms> will be used instead.
292 This sets the supported groups. For clients, the groups are
293 sent using the supported groups extension. For servers, it is used
294 to determine which group to use. This setting affects groups used for both
295 signatures and key exchange, if applicable. It also affects the preferred
296 key_share sent by a client in a TLSv1.3 compatible connection.
298 The B<value> argument is a colon separated list of groups. The group can be
299 either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
300 applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group
301 names are case sensitive. The list should be in order of preference with the
302 most preferred group first. The first listed group will be the one used for a
303 key_share by a TLSv1.3 client.
307 This is a synonym for the "Groups" command.
311 This sets the minimum supported SSL, TLS or DTLS version.
313 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
314 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
315 The value B<None> will disable the limit.
319 This sets the maximum supported SSL, TLS or DTLS version.
321 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
322 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
323 The value B<None> will disable the limit.
327 This can be used to enable or disable certain versions of the SSL,
328 TLS or DTLS protocol.
330 The B<value> argument is a comma separated list of supported protocols
331 to enable or disable.
332 If a protocol is preceded by B<-> that version is disabled.
334 All protocol versions are enabled by default.
335 You need to disable at least one protocol version for this setting have any
337 Only enabling some protocol versions does not disable the other protocol
340 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
341 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
342 The special value B<ALL> refers to all supported versions.
344 This can't enable protocols that are disabled using B<MinProtocol>
345 or B<MaxProtocol>, but can disable protocols that are still allowed
348 The B<Protocol> command is fragile and deprecated; do not use it.
349 Use B<MinProtocol> and B<MaxProtocol> instead.
350 If you do use B<Protocol>, make sure that the resulting range of enabled
351 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
352 sure to also leave TLS 1.1 enabled.
356 The B<value> argument is a comma separated list of various flags to set.
357 If a flag string is preceded B<-> it is disabled.
358 See the L<SSL_CTX_set_options(3)> function for more details of
361 Each option is listed below. Where an operation is enabled by default
362 the B<-flag> syntax is needed to disable it.
364 B<SessionTicket>: session ticket support, enabled by default. Inverse of
365 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
368 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
369 of B<SSL_OP_NO_COMPRESSION>.
371 B<EmptyFragments>: use empty fragments as a countermeasure against a
372 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
373 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
375 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
377 B<DHSingle>: enable single use DH keys, set by default. Inverse of
378 B<SSL_OP_DH_SINGLE>. Only used by servers.
380 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
381 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
383 B<ServerPreference> use server and not client preference order when
384 determining which cipher suite, signature algorithm or elliptic curve
385 to use for an incoming connection. Equivalent to
386 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
388 B<NoResumptionOnRenegotiation> set
389 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
391 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
392 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
394 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
395 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
398 B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
399 default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
400 B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
404 The B<value> argument is a comma separated list of flags to set.
406 B<Peer> enables peer verification: for clients only.
408 B<Request> requests but does not require a certificate from the client.
411 B<Require> requests and requires a certificate from the client: an error
412 occurs if the client does not present a certificate. Servers only.
414 B<Once> requests a certificate from a client only on the initial connection:
415 not when renegotiating. Servers only.
417 =item B<ClientCAFile>, B<ClientCAPath>
419 A file or directory of certificates in PEM format whose names are used as the
420 set of acceptable names for client CAs. Servers only. This option is only
421 supported if certificate operations are permitted.
425 =head1 SUPPORTED COMMAND TYPES
427 The function SSL_CONF_cmd_value_type() currently returns one of the following
432 =item B<SSL_CONF_TYPE_UNKNOWN>
434 The B<cmd> string is unrecognised, this return value can be use to flag
437 =item B<SSL_CONF_TYPE_STRING>
439 The value is a string without any specific structure.
441 =item B<SSL_CONF_TYPE_FILE>
443 The value is a file name.
445 =item B<SSL_CONF_TYPE_DIR>
447 The value is a directory name.
449 =item B<SSL_CONF_TYPE_NONE>
451 The value string is not used e.g. a command line option which doesn't take an
458 The order of operations is significant. This can be used to set either defaults
459 or values which cannot be overridden. For example if an application calls:
461 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
462 SSL_CONF_cmd(ctx, userparam, uservalue);
464 it will disable SSLv3 support by default but the user can override it. If
465 however the call sequence is:
467 SSL_CONF_cmd(ctx, userparam, uservalue);
468 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
470 SSLv3 is B<always> disabled and attempt to override this by the user are
473 By checking the return code of SSL_CONF_cmd() it is possible to query if a
474 given B<cmd> is recognised, this is useful is SSL_CONF_cmd() values are
475 mixed with additional application specific operations.
477 For example an application might call SSL_CONF_cmd() and if it returns
478 -2 (unrecognised command) continue with processing of application specific
481 Applications can also use SSL_CONF_cmd() to process command lines though the
482 utility function SSL_CONF_cmd_argv() is normally used instead. One way
483 to do this is to set the prefix to an appropriate value using
484 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
485 following argument to B<value> (which may be NULL).
487 In this case if the return value is positive then it is used to skip that
488 number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
489 returned then B<cmd> is not recognised and application specific arguments
490 can be checked instead. If -3 is returned a required argument is missing
491 and an error is indicated. If 0 is returned some other error occurred and
492 this can be reported back to the user.
494 The function SSL_CONF_cmd_value_type() can be used by applications to
495 check for the existence of a command or to perform additional syntax
496 checking or translation of the command value. For example if the return
497 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
498 pathname to an absolute pathname.
502 Set supported signature algorithms:
504 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
506 There are various ways to select the supported protocols.
508 This set the minimum protocol version to TLSv1, and so disables SSLv3.
509 This is the recommended way to disable protocols.
511 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
513 The following also disables SSLv3:
515 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
517 The following will first enable all protocols, and then disable
519 If no protocol versions were disabled before this has the same effect as
520 "-SSLv3", but if some versions were disables this will re-enable them before
523 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
527 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
528 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
530 This also only enables TLSv1.2:
532 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
534 Disable TLS session tickets:
536 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
540 SSL_CONF_cmd(ctx, "Options", "Compression");
542 Set supported curves to P-256, P-384:
544 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
546 Set automatic support for any elliptic curve for key exchange:
548 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
552 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
553 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
554 returns the number of arguments processed. This is useful when processing
557 A return value of -2 means B<cmd> is not recognised.
559 A return value of -3 means B<cmd> is recognised and the command requires a
560 value but B<value> is NULL.
562 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
563 error occurred attempting to perform the operation: for example due to an
564 error in the syntax of B<value> in this case the error queue may provide
565 additional information.
569 L<SSL_CONF_CTX_new(3)>,
570 L<SSL_CONF_CTX_set_flags(3)>,
571 L<SSL_CONF_CTX_set1_prefix(3)>,
572 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
573 L<SSL_CONF_cmd_argv(3)>,
574 L<SSL_CTX_set_options(3)>
578 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
580 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
581 for backwards compatibility.
583 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
584 OpenSSL passing a command which didn't take an argument would return
585 B<SSL_CONF_TYPE_UNKNOWN>.
587 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
591 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
593 Licensed under the OpenSSL license (the "License"). You may not use
594 this file except in compliance with the License. You can obtain a copy
595 in the file LICENSE in the source distribution or at
596 L<https://www.openssl.org/source/license.html>.