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>.
189 =item B<-allow_no_dhe_kex>
191 In TLSv1.3 allow a non-(ec)dhe based key exchange mode on resumption. This means
192 that there will be no forward secrecy for the resumed session.
196 enables strict mode protocol handling. Equivalent to setting
197 B<SSL_CERT_FLAG_TLS_STRICT>.
201 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
203 Currently supported B<cmd> names for configuration files (i.e. when the
204 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
205 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
206 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
207 are also case insensitive.
209 Note: the command prefix (if set) alters the recognised B<cmd> values.
213 =item B<CipherString>
215 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
216 currently not performed unless an B<SSL> or B<SSL_CTX> structure is
217 associated with B<cctx>.
221 Attempts to use the file B<value> as the certificate for the appropriate
222 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
223 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
224 structure is set. This option is only supported if certificate operations
229 Attempts to use the file B<value> as the private key for the appropriate
230 context. This option is only supported if certificate operations
231 are permitted. Note: if no B<PrivateKey> option is set then a private key is
232 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
234 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
236 These options indicate a file or directory used for building certificate
237 chains or verifying certificate chains. These options are only supported
238 if certificate operations are permitted.
240 =item B<RequestCAFile>
242 This option indicates a file containing a set of certificates in PEM form.
243 The subject names of the certificates are sent to the peer in the
244 B<certificate_authorities> extension for TLS 1.3 (in ClientHello or
245 CertificateRequest) or in a certificate request for previous versions or
248 =item B<ServerInfoFile>
250 Attempts to use the file B<value> in the "serverinfo" extension using the
251 function SSL_CTX_use_serverinfo_file.
253 =item B<DHParameters>
255 Attempts to use the file B<value> as the set of temporary DH parameters for
256 the appropriate context. This option is only supported if certificate
257 operations are permitted.
259 =item B<RecordPadding>
261 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
262 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
263 B<value> must be >1 or <=16384.
265 =item B<NoRenegotiation>
267 Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting
268 B<SSL_OP_NO_RENEGOTIATION>.
270 =item B<SignatureAlgorithms>
272 This sets the supported signature algorithms for TLS v1.2. For clients this
273 value is used directly for the supported signature algorithms extension. For
274 servers it is used to determine which signature algorithms to support.
276 The B<value> argument should be a colon separated list of signature algorithms
277 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
278 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
279 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
280 Note: algorithm and hash names are case sensitive.
282 If this option is not set then all signature algorithms supported by the
283 OpenSSL library are permissible.
285 =item B<ClientSignatureAlgorithms>
287 This sets the supported signature algorithms associated with client
288 authentication for TLS v1.2. For servers the value is used in the supported
289 signature algorithms field of a certificate request. For clients it is
290 used to determine which signature algorithm to with the client certificate.
292 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
293 the value set for B<SignatureAlgorithms> will be used instead.
297 This sets the supported groups. For clients, the groups are
298 sent using the supported groups extension. For servers, it is used
299 to determine which group to use. This setting affects groups used for both
300 signatures and key exchange, if applicable. It also affects the preferred
301 key_share sent by a client in a TLSv1.3 compatible connection.
303 The B<value> argument is a colon separated list of groups. The group can be
304 either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
305 applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group
306 names are case sensitive. The list should be in order of preference with the
307 most preferred group first. The first listed group will be the one used for a
308 key_share by a TLSv1.3 client.
312 This is a synonym for the "Groups" command.
316 This sets the minimum supported SSL, TLS or DTLS version.
318 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
319 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
320 The value B<None> will disable the limit.
324 This sets the maximum supported SSL, TLS or DTLS version.
326 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
327 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
328 The value B<None> will disable the limit.
332 This can be used to enable or disable certain versions of the SSL,
333 TLS or DTLS protocol.
335 The B<value> argument is a comma separated list of supported protocols
336 to enable or disable.
337 If a protocol is preceded by B<-> that version is disabled.
339 All protocol versions are enabled by default.
340 You need to disable at least one protocol version for this setting have any
342 Only enabling some protocol versions does not disable the other protocol
345 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
346 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
347 The special value B<ALL> refers to all supported versions.
349 This can't enable protocols that are disabled using B<MinProtocol>
350 or B<MaxProtocol>, but can disable protocols that are still allowed
353 The B<Protocol> command is fragile and deprecated; do not use it.
354 Use B<MinProtocol> and B<MaxProtocol> instead.
355 If you do use B<Protocol>, make sure that the resulting range of enabled
356 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
357 sure to also leave TLS 1.1 enabled.
361 The B<value> argument is a comma separated list of various flags to set.
362 If a flag string is preceded B<-> it is disabled.
363 See the L<SSL_CTX_set_options(3)> function for more details of
366 Each option is listed below. Where an operation is enabled by default
367 the B<-flag> syntax is needed to disable it.
369 B<SessionTicket>: session ticket support, enabled by default. Inverse of
370 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
373 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
374 of B<SSL_OP_NO_COMPRESSION>.
376 B<EmptyFragments>: use empty fragments as a countermeasure against a
377 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
378 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
380 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
382 B<DHSingle>: enable single use DH keys, set by default. Inverse of
383 B<SSL_OP_DH_SINGLE>. Only used by servers.
385 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
386 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
388 B<ServerPreference> use server and not client preference order when
389 determining which cipher suite, signature algorithm or elliptic curve
390 to use for an incoming connection. Equivalent to
391 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
393 B<NoResumptionOnRenegotiation> set
394 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
396 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
397 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
399 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
400 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
403 B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
404 default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
405 B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
407 B<AllowNoDHEKEX>: In TLSv1.3 allow a non-(ec)dhe based key exchange mode on
408 resumption. This means that there will be no forward secrecy for the resumed
409 session. Equivalent to B<SSL_OP_ALLOW_NO_DHE_KEX>.
413 The B<value> argument is a comma separated list of flags to set.
415 B<Peer> enables peer verification: for clients only.
417 B<Request> requests but does not require a certificate from the client.
420 B<Require> requests and requires a certificate from the client: an error
421 occurs if the client does not present a certificate. Servers only.
423 B<Once> requests a certificate from a client only on the initial connection:
424 not when renegotiating. Servers only.
426 =item B<ClientCAFile>, B<ClientCAPath>
428 A file or directory of certificates in PEM format whose names are used as the
429 set of acceptable names for client CAs. Servers only. This option is only
430 supported if certificate operations are permitted.
434 =head1 SUPPORTED COMMAND TYPES
436 The function SSL_CONF_cmd_value_type() currently returns one of the following
441 =item B<SSL_CONF_TYPE_UNKNOWN>
443 The B<cmd> string is unrecognised, this return value can be use to flag
446 =item B<SSL_CONF_TYPE_STRING>
448 The value is a string without any specific structure.
450 =item B<SSL_CONF_TYPE_FILE>
452 The value is a file name.
454 =item B<SSL_CONF_TYPE_DIR>
456 The value is a directory name.
458 =item B<SSL_CONF_TYPE_NONE>
460 The value string is not used e.g. a command line option which doesn't take an
467 The order of operations is significant. This can be used to set either defaults
468 or values which cannot be overridden. For example if an application calls:
470 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
471 SSL_CONF_cmd(ctx, userparam, uservalue);
473 it will disable SSLv3 support by default but the user can override it. If
474 however the call sequence is:
476 SSL_CONF_cmd(ctx, userparam, uservalue);
477 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
479 SSLv3 is B<always> disabled and attempt to override this by the user are
482 By checking the return code of SSL_CONF_cmd() it is possible to query if a
483 given B<cmd> is recognised, this is useful is SSL_CONF_cmd() values are
484 mixed with additional application specific operations.
486 For example an application might call SSL_CONF_cmd() and if it returns
487 -2 (unrecognised command) continue with processing of application specific
490 Applications can also use SSL_CONF_cmd() to process command lines though the
491 utility function SSL_CONF_cmd_argv() is normally used instead. One way
492 to do this is to set the prefix to an appropriate value using
493 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
494 following argument to B<value> (which may be NULL).
496 In this case if the return value is positive then it is used to skip that
497 number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
498 returned then B<cmd> is not recognised and application specific arguments
499 can be checked instead. If -3 is returned a required argument is missing
500 and an error is indicated. If 0 is returned some other error occurred and
501 this can be reported back to the user.
503 The function SSL_CONF_cmd_value_type() can be used by applications to
504 check for the existence of a command or to perform additional syntax
505 checking or translation of the command value. For example if the return
506 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
507 pathname to an absolute pathname.
511 Set supported signature algorithms:
513 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
515 There are various ways to select the supported protocols.
517 This set the minimum protocol version to TLSv1, and so disables SSLv3.
518 This is the recommended way to disable protocols.
520 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
522 The following also disables SSLv3:
524 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
526 The following will first enable all protocols, and then disable
528 If no protocol versions were disabled before this has the same effect as
529 "-SSLv3", but if some versions were disables this will re-enable them before
532 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
536 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
537 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
539 This also only enables TLSv1.2:
541 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
543 Disable TLS session tickets:
545 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
549 SSL_CONF_cmd(ctx, "Options", "Compression");
551 Set supported curves to P-256, P-384:
553 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
555 Set automatic support for any elliptic curve for key exchange:
557 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
561 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
562 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
563 returns the number of arguments processed. This is useful when processing
566 A return value of -2 means B<cmd> is not recognised.
568 A return value of -3 means B<cmd> is recognised and the command requires a
569 value but B<value> is NULL.
571 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
572 error occurred attempting to perform the operation: for example due to an
573 error in the syntax of B<value> in this case the error queue may provide
574 additional information.
578 L<SSL_CONF_CTX_new(3)>,
579 L<SSL_CONF_CTX_set_flags(3)>,
580 L<SSL_CONF_CTX_set1_prefix(3)>,
581 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
582 L<SSL_CONF_cmd_argv(3)>,
583 L<SSL_CTX_set_options(3)>
587 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
589 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
590 for backwards compatibility.
592 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
593 OpenSSL passing a command which didn't take an argument would return
594 B<SSL_CONF_TYPE_UNKNOWN>.
596 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
600 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
602 Licensed under the OpenSSL license (the "License"). You may not use
603 this file except in compliance with the License. You can obtain a copy
604 in the file LICENSE in the source distribution or at
605 L<https://www.openssl.org/source/license.html>.