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diff --git a/doc/man3/SSL_CONF_cmd.pod b/doc/man3/SSL_CONF_cmd.pod new file mode 100644 index 000000000000..b399bcf4990c --- /dev/null +++ b/doc/man3/SSL_CONF_cmd.pod @@ -0,0 +1,695 @@ +=pod + +=head1 NAME + +SSL_CONF_cmd_value_type, +SSL_CONF_cmd - send configuration command + +=head1 SYNOPSIS + + #include <openssl/ssl.h> + + int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value); + int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd); + +=head1 DESCRIPTION + +The function SSL_CONF_cmd() performs configuration operation B<cmd> with +optional parameter B<value> on B<ctx>. Its purpose is to simplify application +configuration of B<SSL_CTX> or B<SSL> structures by providing a common +framework for command line options or configuration files. + +SSL_CONF_cmd_value_type() returns the type of value that B<cmd> refers to. + +=head1 SUPPORTED COMMAND LINE COMMANDS + +Currently supported B<cmd> names for command lines (i.e. when the +flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<cmd> names +are case sensitive. Unless otherwise stated commands can be used by +both clients and servers and the B<value> parameter is not used. The default +prefix for command line commands is B<-> and that is reflected below. + +=over 4 + +=item B<-sigalgs> + +This sets the supported signature algorithms for TLSv1.2 and TLSv1.3. +For clients this +value is used directly for the supported signature algorithms extension. For +servers it is used to determine which signature algorithms to support. + +The B<value> argument should be a colon separated list of signature algorithms +in order of decreasing preference of the form B<algorithm+hash> or +B<signature_scheme>. B<algorithm> +is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm +OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>. +Note: algorithm and hash names are case sensitive. +B<signature_scheme> is one of the signature schemes defined in TLSv1.3, +specified using the IETF name, e.g., B<ecdsa_secp256r1_sha256>, B<ed25519>, +or B<rsa_pss_pss_sha256>. + +If this option is not set then all signature algorithms supported by the +OpenSSL library are permissible. + +Note: algorithms which specify a PKCS#1 v1.5 signature scheme (either by +using B<RSA> as the B<algorithm> or by using one of the B<rsa_pkcs1_*> +identifiers) are ignored in TLSv1.3 and will not be negotiated. + +=item B<-client_sigalgs> + +This sets the supported signature algorithms associated with client +authentication for TLSv1.2 and TLSv1.3. +For servers the value is used in the +B<signature_algorithms> field of a B<CertificateRequest> message. +For clients it is +used to determine which signature algorithm to use with the client certificate. +If a server does not request a certificate this option has no effect. + +The syntax of B<value> is identical to B<-sigalgs>. If not set then +the value set for B<-sigalgs> will be used instead. + +=item B<-groups> + +This sets the supported groups. For clients, the groups are +sent using the supported groups extension. For servers, it is used +to determine which group to use. This setting affects groups used for +signatures (in TLSv1.2 and earlier) and key exchange. The first group listed +will also be used for the B<key_share> sent by a client in a TLSv1.3 +B<ClientHello>. + +The B<value> argument is a colon separated list of groups. The group can be +either the B<NIST> name (e.g. B<P-256>), some other commonly used name where +applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group +names are case sensitive. The list should be in order of preference with the +most preferred group first. + +=item B<-curves> + +This is a synonym for the "-groups" command. + +=item B<-named_curve> + +This sets the temporary curve used for ephemeral ECDH modes. Only used by +servers + +The B<value> argument is a curve name or the special value B<auto> which +picks an appropriate curve based on client and server preferences. The curve +can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name +(e.g B<prime256v1>). Curve names are case sensitive. + +=item B<-cipher> + +Sets the TLSv1.2 and below ciphersuite list to B<value>. This list will be +combined with any configured TLSv1.3 ciphersuites. Note: syntax checking +of B<value> is currently not performed unless a B<SSL> or B<SSL_CTX> structure is +associated with B<cctx>. + +=item B<-ciphersuites> + +Sets the available ciphersuites for TLSv1.3 to value. This is a simple colon +(":") separated list of TLSv1.3 ciphersuite names in order of preference. This +list will be combined any configured TLSv1.2 and below ciphersuites. +See L<ciphers(1)> for more information. + + +=item B<-cert> + +Attempts to use the file B<value> as the certificate for the appropriate +context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX> +structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL> +structure is set. This option is only supported if certificate operations +are permitted. + +=item B<-key> + +Attempts to use the file B<value> as the private key for the appropriate +context. This option is only supported if certificate operations +are permitted. Note: if no B<-key> option is set then a private key is +not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set. + +=item B<-dhparam> + +Attempts to use the file B<value> as the set of temporary DH parameters for +the appropriate context. This option is only supported if certificate +operations are permitted. + +=item B<-record_padding> + +Attempts to pad TLSv1.3 records so that they are a multiple of B<value> in +length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the +B<value> must be >1 or <=16384. + +=item B<-no_renegotiation> + +Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting +B<SSL_OP_NO_RENEGOTIATION>. + +=item B<-min_protocol>, B<-max_protocol> + +Sets the minimum and maximum supported protocol. +Currently supported protocol values are B<SSLv3>, B<TLSv1>, +B<TLSv1.1>, B<TLSv1.2>, B<TLSv1.3> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS, +and B<None> for no limit. +If either bound is not specified then only the other bound applies, +if specified. +To restrict the supported protocol versions use these commands rather +than the deprecated alternative commands below. + +=item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3> + +Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by +setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>, +B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3> +respectively. These options are deprecated, instead use B<-min_protocol> and +B<-max_protocol>. + +=item B<-bugs> + +Various bug workarounds are set, same as setting B<SSL_OP_ALL>. + +=item B<-comp> + +Enables support for SSL/TLS compression, same as clearing +B<SSL_OP_NO_COMPRESSION>. +This command was introduced in OpenSSL 1.1.0. +As of OpenSSL 1.1.0, compression is off by default. + +=item B<-no_comp> + +Disables support for SSL/TLS compression, same as setting +B<SSL_OP_NO_COMPRESSION>. +As of OpenSSL 1.1.0, compression is off by default. + +=item B<-no_ticket> + +Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>. + +=item B<-serverpref> + +Use server and not client preference order when determining which cipher suite, +signature algorithm or elliptic curve to use for an incoming connection. +Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers. + +=item B<-prioritize_chacha> + +Prioritize ChaCha ciphers when the client has a ChaCha20 cipher at the top of +its preference list. This usually indicates a client without AES hardware +acceleration (e.g. mobile) is in use. Equivalent to B<SSL_OP_PRIORITIZE_CHACHA>. +Only used by servers. Requires B<-serverpref>. + +=item B<-no_resumption_on_reneg> + +set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers. + +=item B<-legacyrenegotiation> + +permits the use of unsafe legacy renegotiation. Equivalent to setting +B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>. + +=item B<-legacy_server_connect>, B<-no_legacy_server_connect> + +permits or prohibits the use of unsafe legacy renegotiation for OpenSSL +clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>. +Set by default. + +=item B<-allow_no_dhe_kex> + +In TLSv1.3 allow a non-(ec)dhe based key exchange mode on resumption. This means +that there will be no forward secrecy for the resumed session. + +=item B<-strict> + +enables strict mode protocol handling. Equivalent to setting +B<SSL_CERT_FLAG_TLS_STRICT>. + +=item B<-anti_replay>, B<-no_anti_replay> + +Switches replay protection, on or off respectively. With replay protection on, +OpenSSL will automatically detect if a session ticket has been used more than +once, TLSv1.3 has been negotiated, and early data is enabled on the server. A +full handshake is forced if a session ticket is used a second or subsequent +time. Anti-Replay is on by default unless overridden by a configuration file and +is only used by servers. Anti-replay measures are required for compliance with +the TLSv1.3 specification. Some applications may be able to mitigate the replay +risks in other ways and in such cases the built-in OpenSSL functionality is not +required. Switching off anti-replay is equivalent to B<SSL_OP_NO_ANTI_REPLAY>. + +=back + +=head1 SUPPORTED CONFIGURATION FILE COMMANDS + +Currently supported B<cmd> names for configuration files (i.e. when the +flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file +B<cmd> names are case insensitive so B<signaturealgorithms> is recognised +as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names +are also case insensitive. + +Note: the command prefix (if set) alters the recognised B<cmd> values. + +=over 4 + +=item B<CipherString> + +Sets the ciphersuite list for TLSv1.2 and below to B<value>. This list will be +combined with any configured TLSv1.3 ciphersuites. Note: syntax +checking of B<value> is currently not performed unless an B<SSL> or B<SSL_CTX> +structure is associated with B<cctx>. + +=item B<Ciphersuites> + +Sets the available ciphersuites for TLSv1.3 to B<value>. This is a simple colon +(":") separated list of TLSv1.3 ciphersuite names in order of preference. This +list will be combined any configured TLSv1.2 and below ciphersuites. +See L<ciphers(1)> for more information. + +=item B<Certificate> + +Attempts to use the file B<value> as the certificate for the appropriate +context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX> +structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL> +structure is set. This option is only supported if certificate operations +are permitted. + +=item B<PrivateKey> + +Attempts to use the file B<value> as the private key for the appropriate +context. This option is only supported if certificate operations +are permitted. Note: if no B<PrivateKey> option is set then a private key is +not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set. + +=item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath> + +These options indicate a file or directory used for building certificate +chains or verifying certificate chains. These options are only supported +if certificate operations are permitted. + +=item B<RequestCAFile> + +This option indicates a file containing a set of certificates in PEM form. +The subject names of the certificates are sent to the peer in the +B<certificate_authorities> extension for TLS 1.3 (in ClientHello or +CertificateRequest) or in a certificate request for previous versions or +TLS. + +=item B<ServerInfoFile> + +Attempts to use the file B<value> in the "serverinfo" extension using the +function SSL_CTX_use_serverinfo_file. + +=item B<DHParameters> + +Attempts to use the file B<value> as the set of temporary DH parameters for +the appropriate context. This option is only supported if certificate +operations are permitted. + +=item B<RecordPadding> + +Attempts to pad TLSv1.3 records so that they are a multiple of B<value> in +length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the +B<value> must be >1 or <=16384. + +=item B<NoRenegotiation> + +Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting +B<SSL_OP_NO_RENEGOTIATION>. + +=item B<SignatureAlgorithms> + +This sets the supported signature algorithms for TLSv1.2 and TLSv1.3. +For clients this +value is used directly for the supported signature algorithms extension. For +servers it is used to determine which signature algorithms to support. + +The B<value> argument should be a colon separated list of signature algorithms +in order of decreasing preference of the form B<algorithm+hash> or +B<signature_scheme>. B<algorithm> +is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm +OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>. +Note: algorithm and hash names are case sensitive. +B<signature_scheme> is one of the signature schemes defined in TLSv1.3, +specified using the IETF name, e.g., B<ecdsa_secp256r1_sha256>, B<ed25519>, +or B<rsa_pss_pss_sha256>. + +If this option is not set then all signature algorithms supported by the +OpenSSL library are permissible. + +Note: algorithms which specify a PKCS#1 v1.5 signature scheme (either by +using B<RSA> as the B<algorithm> or by using one of the B<rsa_pkcs1_*> +identifiers) are ignored in TLSv1.3 and will not be negotiated. + +=item B<ClientSignatureAlgorithms> + +This sets the supported signature algorithms associated with client +authentication for TLSv1.2 and TLSv1.3. +For servers the value is used in the +B<signature_algorithms> field of a B<CertificateRequest> message. +For clients it is +used to determine which signature algorithm to use with the client certificate. +If a server does not request a certificate this option has no effect. + +The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then +the value set for B<SignatureAlgorithms> will be used instead. + +=item B<Groups> + +This sets the supported groups. For clients, the groups are +sent using the supported groups extension. For servers, it is used +to determine which group to use. This setting affects groups used for +signatures (in TLSv1.2 and earlier) and key exchange. The first group listed +will also be used for the B<key_share> sent by a client in a TLSv1.3 +B<ClientHello>. + +The B<value> argument is a colon separated list of groups. The group can be +either the B<NIST> name (e.g. B<P-256>), some other commonly used name where +applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group +names are case sensitive. The list should be in order of preference with the +most preferred group first. + +=item B<Curves> + +This is a synonym for the "Groups" command. + +=item B<MinProtocol> + +This sets the minimum supported SSL, TLS or DTLS version. + +Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>, +B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>. +The value B<None> will disable the limit. + +=item B<MaxProtocol> + +This sets the maximum supported SSL, TLS or DTLS version. + +Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>, +B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>. +The value B<None> will disable the limit. + +=item B<Protocol> + +This can be used to enable or disable certain versions of the SSL, +TLS or DTLS protocol. + +The B<value> argument is a comma separated list of supported protocols +to enable or disable. +If a protocol is preceded by B<-> that version is disabled. + +All protocol versions are enabled by default. +You need to disable at least one protocol version for this setting have any +effect. +Only enabling some protocol versions does not disable the other protocol +versions. + +Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>, +B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>. +The special value B<ALL> refers to all supported versions. + +This can't enable protocols that are disabled using B<MinProtocol> +or B<MaxProtocol>, but can disable protocols that are still allowed +by them. + +The B<Protocol> command is fragile and deprecated; do not use it. +Use B<MinProtocol> and B<MaxProtocol> instead. +If you do use B<Protocol>, make sure that the resulting range of enabled +protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make +sure to also leave TLS 1.1 enabled. + +=item B<Options> + +The B<value> argument is a comma separated list of various flags to set. +If a flag string is preceded B<-> it is disabled. +See the L<SSL_CTX_set_options(3)> function for more details of +individual options. + +Each option is listed below. Where an operation is enabled by default +the B<-flag> syntax is needed to disable it. + +B<SessionTicket>: session ticket support, enabled by default. Inverse of +B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting +B<SSL_OP_NO_TICKET>. + +B<Compression>: SSL/TLS compression support, enabled by default. Inverse +of B<SSL_OP_NO_COMPRESSION>. + +B<EmptyFragments>: use empty fragments as a countermeasure against a +SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It +is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>. + +B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>. + +B<DHSingle>: enable single use DH keys, set by default. Inverse of +B<SSL_OP_DH_SINGLE>. Only used by servers. + +B<ECDHSingle>: enable single use ECDH keys, set by default. Inverse of +B<SSL_OP_ECDH_SINGLE>. Only used by servers. + +B<ServerPreference>: use server and not client preference order when +determining which cipher suite, signature algorithm or elliptic curve +to use for an incoming connection. Equivalent to +B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers. + +B<PrioritizeChaCha>: prioritizes ChaCha ciphers when the client has a +ChaCha20 cipher at the top of its preference list. This usually indicates +a mobile client is in use. Equivalent to B<SSL_OP_PRIORITIZE_CHACHA>. +Only used by servers. + +B<NoResumptionOnRenegotiation>: set +B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers. + +B<UnsafeLegacyRenegotiation>: permits the use of unsafe legacy renegotiation. +Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>. + +B<UnsafeLegacyServerConnect>: permits the use of unsafe legacy renegotiation +for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>. +Set by default. + +B<EncryptThenMac>: use encrypt-then-mac extension, enabled by +default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is, +B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>. + +B<AllowNoDHEKEX>: In TLSv1.3 allow a non-(ec)dhe based key exchange mode on +resumption. This means that there will be no forward secrecy for the resumed +session. Equivalent to B<SSL_OP_ALLOW_NO_DHE_KEX>. + +B<MiddleboxCompat>: If set then dummy Change Cipher Spec (CCS) messages are sent +in TLSv1.3. This has the effect of making TLSv1.3 look more like TLSv1.2 so that +middleboxes that do not understand TLSv1.3 will not drop the connection. This +option is set by default. A future version of OpenSSL may not set this by +default. Equivalent to B<SSL_OP_ENABLE_MIDDLEBOX_COMPAT>. + +B<AntiReplay>: If set then OpenSSL will automatically detect if a session ticket +has been used more than once, TLSv1.3 has been negotiated, and early data is +enabled on the server. A full handshake is forced if a session ticket is used a +second or subsequent time. This option is set by default and is only used by +servers. Anti-replay measures are required to comply with the TLSv1.3 +specification. Some applications may be able to mitigate the replay risks in +other ways and in such cases the built-in OpenSSL functionality is not required. +Disabling anti-replay is equivalent to setting B<SSL_OP_NO_ANTI_REPLAY>. + +=item B<VerifyMode> + +The B<value> argument is a comma separated list of flags to set. + +B<Peer> enables peer verification: for clients only. + +B<Request> requests but does not require a certificate from the client. +Servers only. + +B<Require> requests and requires a certificate from the client: an error +occurs if the client does not present a certificate. Servers only. + +B<Once> requests a certificate from a client only on the initial connection: +not when renegotiating. Servers only. + +B<RequestPostHandshake> configures the connection to support requests but does +not require a certificate from the client post-handshake. A certificate will +not be requested during the initial handshake. The server application must +provide a mechanism to request a certificate post-handshake. Servers only. +TLSv1.3 only. + +B<RequiresPostHandshake> configures the connection to support requests and +requires a certificate from the client post-handshake: an error occurs if the +client does not present a certificate. A certificate will not be requested +during the initial handshake. The server application must provide a mechanism +to request a certificate post-handshake. Servers only. TLSv1.3 only. + +=item B<ClientCAFile>, B<ClientCAPath> + +A file or directory of certificates in PEM format whose names are used as the +set of acceptable names for client CAs. Servers only. This option is only +supported if certificate operations are permitted. + +=back + +=head1 SUPPORTED COMMAND TYPES + +The function SSL_CONF_cmd_value_type() currently returns one of the following +types: + +=over 4 + +=item B<SSL_CONF_TYPE_UNKNOWN> + +The B<cmd> string is unrecognised, this return value can be use to flag +syntax errors. + +=item B<SSL_CONF_TYPE_STRING> + +The value is a string without any specific structure. + +=item B<SSL_CONF_TYPE_FILE> + +The value is a file name. + +=item B<SSL_CONF_TYPE_DIR> + +The value is a directory name. + +=item B<SSL_CONF_TYPE_NONE> + +The value string is not used e.g. a command line option which doesn't take an +argument. + +=back + +=head1 NOTES + +The order of operations is significant. This can be used to set either defaults +or values which cannot be overridden. For example if an application calls: + + SSL_CONF_cmd(ctx, "Protocol", "-SSLv3"); + SSL_CONF_cmd(ctx, userparam, uservalue); + +it will disable SSLv3 support by default but the user can override it. If +however the call sequence is: + + SSL_CONF_cmd(ctx, userparam, uservalue); + SSL_CONF_cmd(ctx, "Protocol", "-SSLv3"); + +SSLv3 is B<always> disabled and attempt to override this by the user are +ignored. + +By checking the return code of SSL_CONF_cmd() it is possible to query if a +given B<cmd> is recognised, this is useful if SSL_CONF_cmd() values are +mixed with additional application specific operations. + +For example an application might call SSL_CONF_cmd() and if it returns +-2 (unrecognised command) continue with processing of application specific +commands. + +Applications can also use SSL_CONF_cmd() to process command lines though the +utility function SSL_CONF_cmd_argv() is normally used instead. One way +to do this is to set the prefix to an appropriate value using +SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the +following argument to B<value> (which may be NULL). + +In this case if the return value is positive then it is used to skip that +number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is +returned then B<cmd> is not recognised and application specific arguments +can be checked instead. If -3 is returned a required argument is missing +and an error is indicated. If 0 is returned some other error occurred and +this can be reported back to the user. + +The function SSL_CONF_cmd_value_type() can be used by applications to +check for the existence of a command or to perform additional syntax +checking or translation of the command value. For example if the return +value is B<SSL_CONF_TYPE_FILE> an application could translate a relative +pathname to an absolute pathname. + +=head1 EXAMPLES + +Set supported signature algorithms: + + SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256"); + +There are various ways to select the supported protocols. + +This set the minimum protocol version to TLSv1, and so disables SSLv3. +This is the recommended way to disable protocols. + + SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1"); + +The following also disables SSLv3: + + SSL_CONF_cmd(ctx, "Protocol", "-SSLv3"); + +The following will first enable all protocols, and then disable +SSLv3. +If no protocol versions were disabled before this has the same effect as +"-SSLv3", but if some versions were disables this will re-enable them before +disabling SSLv3. + + SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3"); + +Only enable TLSv1.2: + + SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2"); + SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2"); + +This also only enables TLSv1.2: + + SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2"); + +Disable TLS session tickets: + + SSL_CONF_cmd(ctx, "Options", "-SessionTicket"); + +Enable compression: + + SSL_CONF_cmd(ctx, "Options", "Compression"); + +Set supported curves to P-256, P-384: + + SSL_CONF_cmd(ctx, "Curves", "P-256:P-384"); + +=head1 RETURN VALUES + +SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is +B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it +returns the number of arguments processed. This is useful when processing +command lines. + +A return value of -2 means B<cmd> is not recognised. + +A return value of -3 means B<cmd> is recognised and the command requires a +value but B<value> is NULL. + +A return code of 0 indicates that both B<cmd> and B<value> are valid but an +error occurred attempting to perform the operation: for example due to an +error in the syntax of B<value> in this case the error queue may provide +additional information. + +=head1 SEE ALSO + +L<SSL_CONF_CTX_new(3)>, +L<SSL_CONF_CTX_set_flags(3)>, +L<SSL_CONF_CTX_set1_prefix(3)>, +L<SSL_CONF_CTX_set_ssl_ctx(3)>, +L<SSL_CONF_cmd_argv(3)>, +L<SSL_CTX_set_options(3)> + +=head1 HISTORY + +SSL_CONF_cmd() was first added to OpenSSL 1.0.2 + +B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained +for backwards compatibility. + +B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of +OpenSSL passing a command which didn't take an argument would return +B<SSL_CONF_TYPE_UNKNOWN>. + +B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0. + +B<AllowNoDHEKEX> and B<PrioritizeChaCha> were added in OpenSSL 1.1.1. + +=head1 COPYRIGHT + +Copyright 2012-2018 The OpenSSL Project Authors. All Rights Reserved. + +Licensed under the OpenSSL license (the "License"). You may not use +this file except in compliance with the License. You can obtain a copy +in the file LICENSE in the source distribution or at +L<https://www.openssl.org/source/license.html>. + +=cut |