554 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
			
		
		
	
	
			554 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
=pod
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=head1 NAME
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SSL_CONF_cmd - send configuration command
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=head1 SYNOPSIS
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 #include <openssl/ssl.h>
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 int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value);
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 int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd);
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 int SSL_CONF_finish(SSL_CONF_CTX *cctx);
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=head1 DESCRIPTION
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The function SSL_CONF_cmd() performs configuration operation B<cmd> with
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optional parameter B<value> on B<ctx>. Its purpose is to simplify application
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configuration of B<SSL_CTX> or B<SSL> structures by providing a common
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framework for command line options or configuration files.
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SSL_CONF_cmd_value_type() returns the type of value that B<cmd> refers to.
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The function SSL_CONF_finish() must be called after all configuration
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operations have been completed. It is used to finalise any operations
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or to process defaults.
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=head1 SUPPORTED COMMAND LINE COMMANDS
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Currently supported B<cmd> names for command lines (i.e. when the
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flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<cmd> names
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are case sensitive. Unless otherwise stated commands can be used by
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both clients and servers and the B<value> parameter is not used. The default
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prefix for command line commands is B<-> and that is reflected below.
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=over 4
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=item B<-sigalgs>
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This sets the supported signature algorithms for TLS v1.2. For clients this
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value is used directly for the supported signature algorithms extension. For
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servers it is used to determine which signature algorithms to support.
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The B<value> argument should be a colon separated list of signature algorithms
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in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
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is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
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OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
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Note: algorithm and hash names are case sensitive.
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If this option is not set then all signature algorithms supported by the
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OpenSSL library are permissible.
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=item B<-client_sigalgs>
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This sets the supported signature algorithms associated with client
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authentication for TLS v1.2. For servers the value is used in the supported
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signature algorithms field of a certificate request. For clients it is
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used to determine which signature algorithm to with the client certificate.
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If a server does not request a certificate this option has no effect.
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The syntax of B<value> is identical to B<-sigalgs>. If not set then
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the value set for B<-sigalgs> will be used instead.
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=item B<-curves>
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This sets the supported elliptic curves. For clients the curves are
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sent using the supported curves extension. For servers it is used
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to determine which curve to use. This setting affects curves used for both
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signatures and key exchange, if applicable.
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The B<value> argument is a colon separated list of curves. The curve can be
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either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
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B<prime256v1>). Curve names are case sensitive.
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=item B<-named_curve>
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This sets the temporary curve used for ephemeral ECDH modes. Only used by
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servers
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The B<value> argument is a curve name or the special value B<auto> which
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picks an appropriate curve based on client and server preferences. The curve
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can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
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(e.g B<prime256v1>). Curve names are case sensitive.
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=item B<-cipher>
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Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
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currently not performed unless a B<SSL> or B<SSL_CTX> structure is
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associated with B<cctx>.
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=item B<-cert>
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Attempts to use the file B<value> as the certificate for the appropriate
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context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
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structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
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structure is set. This option is only supported if certificate operations
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are permitted.
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=item B<-key>
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Attempts to use the file B<value> as the private key for the appropriate
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context. This option is only supported if certificate operations
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are permitted. Note: if no B<-key> option is set then a private key is
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not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
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=item B<-dhparam>
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Attempts to use the file B<value> as the set of temporary DH parameters for
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the appropriate context. This option is only supported if certificate
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operations are permitted.
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=item B<-min_protocol>, B<-max_protocol>
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Sets the minimum and maximum supported protocol.
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Currently supported protocol values are B<SSLv3>, B<TLSv1>,
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B<TLSv1.1>, B<TLSv1.2> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
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and B<None> for no limit.
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If the either bound is not specified then only the other bound applies,
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if specified.
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To restrict the supported protocol versions use these commands rather
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than the deprecated alternative commands below.
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=item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>
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Disables protocol support for SSLv3, TLSv1.0, TLSv1.1 or TLSv1.2 by setting the
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corresponding options B<SSL_OP_NO_SSL3>, B<SSL_OP_NO_TLS1>, B<SSL_OP_NO_TLS1_1>
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and B<SSL_OP_NO_TLS1_2> respectively.
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These options are deprecated, instead use B<-min_protocol> and B<-max_protocol>.
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=item B<-bugs>
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Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
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=item B<-comp>
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Enables support for SSL/TLS compression, same as clearing
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B<SSL_OP_NO_COMPRESSION>.
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This command was introduced in OpenSSL 1.1.0.
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As of OpenSSL 1.1.0, compression is off by default.
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=item B<-no_comp>
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Disables support for SSL/TLS compression, same as setting
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B<SSL_OP_NO_COMPRESSION>.
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As of OpenSSL 1.1.0, compression is off by default.
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=item B<-no_ticket>
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Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
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=item B<-serverpref>
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Use server and not client preference order when determining which cipher suite,
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signature algorithm or elliptic curve to use for an incoming connection.
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Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
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=item B<-no_resumption_on_reneg>
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set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
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=item B<-legacyrenegotiation>
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permits the use of unsafe legacy renegotiation. Equivalent to setting
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B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
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=item B<-legacy_server_connect>, B<-no_legacy_server_connect>
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permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
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clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
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Set by default.
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=item B<-strict>
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enables strict mode protocol handling. Equivalent to setting
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B<SSL_CERT_FLAG_TLS_STRICT>.
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=back
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=head1 SUPPORTED CONFIGURATION FILE COMMANDS
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Currently supported B<cmd> names for configuration files (i.e. when the
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flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
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B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
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as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
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are also case insensitive.
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Note: the command prefix (if set) alters the recognised B<cmd> values.
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=over 4
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=item B<CipherString>
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Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
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currently not performed unless an B<SSL> or B<SSL_CTX> structure is
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associated with B<cctx>.
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=item B<Certificate>
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Attempts to use the file B<value> as the certificate for the appropriate
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context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
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structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
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structure is set. This option is only supported if certificate operations
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are permitted.
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=item B<PrivateKey>
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Attempts to use the file B<value> as the private key for the appropriate
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context. This option is only supported if certificate operations
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are permitted. Note: if no B<PrivateKey> option is set then a private key is
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not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
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=item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
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These options indicate a file or directory used for building certificate
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chains or verifying certificate chains. These options are only supported
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if certificate operations are permitted.
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=item B<ServerInfoFile>
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Attempts to use the file B<value> in the "serverinfo" extension using the
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function SSL_CTX_use_serverinfo_file.
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=item B<DHParameters>
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Attempts to use the file B<value> as the set of temporary DH parameters for
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the appropriate context. This option is only supported if certificate
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operations are permitted.
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=item B<SignatureAlgorithms>
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This sets the supported signature algorithms for TLS v1.2. For clients this
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value is used directly for the supported signature algorithms extension. For
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servers it is used to determine which signature algorithms to support.
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The B<value> argument should be a colon separated list of signature algorithms
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in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
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is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
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OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
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Note: algorithm and hash names are case sensitive.
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If this option is not set then all signature algorithms supported by the
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OpenSSL library are permissible.
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=item B<ClientSignatureAlgorithms>
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This sets the supported signature algorithms associated with client
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authentication for TLS v1.2. For servers the value is used in the supported
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signature algorithms field of a certificate request. For clients it is
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used to determine which signature algorithm to with the client certificate.
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The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
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the value set for B<SignatureAlgorithms> will be used instead.
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=item B<Curves>
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This sets the supported elliptic curves. For clients the curves are
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sent using the supported curves extension. For servers it is used
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to determine which curve to use. This setting affects curves used for both
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signatures and key exchange, if applicable.
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The B<value> argument is a colon separated list of curves. The curve can be
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either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
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B<prime256v1>). Curve names are case sensitive.
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=item B<ECDHParameters>
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This sets the temporary curve used for ephemeral ECDH modes. Only used by
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servers
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The B<value> argument is a curve name or the special value B<Automatic> which
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picks an appropriate curve based on client and server preferences. The curve
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can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
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(e.g B<prime256v1>). Curve names are case sensitive.
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=item B<MinProtocol>
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This sets the minimum supported SSL, TLS or DTLS version.
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Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
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B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
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The value B<None> will disable the limit.
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=item B<MaxProtocol>
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This sets the maximum supported SSL, TLS or DTLS version.
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Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
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B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
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The value B<None> will disable the limit.
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=item B<Protocol>
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This can be used to enable or disable certain versions of the SSL,
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TLS or DTLS protocol.
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The B<value> argument is a comma separated list of supported protocols
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to enable or disable.
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If a protocol is preceded by B<-> that version is disabled.
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All protocol versions are enabled by default.
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You need to disable at least one protocol version for this setting have any
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effect.
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Only enabling some protocol versions does not disable the other protocol
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versions.
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Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
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B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
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The special value B<ALL> refers to all supported versions.
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This can't enable protocols that are disabled using B<MinProtocol>
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or B<MaxProtocol>, but can disable protocols that are still allowed
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by them.
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The B<Protocol> command is fragile and deprecated; do not use it.
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Use B<MinProtocol> and B<MaxProtocol> instead.
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If you do use B<Protocol>, make sure that the resulting range of enabled
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protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
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sure to also leave TLS 1.1 enabled.
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=item B<Options>
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The B<value> argument is a comma separated list of various flags to set.
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If a flag string is preceded B<-> it is disabled.
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See the L<SSL_CTX_set_options(3)> function for more details of
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individual options.
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Each option is listed below. Where an operation is enabled by default
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the B<-flag> syntax is needed to disable it.
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B<SessionTicket>: session ticket support, enabled by default. Inverse of
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B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
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B<SSL_OP_NO_TICKET>.
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B<Compression>: SSL/TLS compression support, enabled by default. Inverse
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of B<SSL_OP_NO_COMPRESSION>.
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B<EmptyFragments>: use empty fragments as a countermeasure against a
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SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
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is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
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B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
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B<DHSingle>: enable single use DH keys, set by default. Inverse of
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B<SSL_OP_DH_SINGLE>. Only used by servers.
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B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
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B<SSL_OP_ECDH_SINGLE>. Only used by servers.
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B<ServerPreference> use server and not client preference order when
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determining which cipher suite, signature algorithm or elliptic curve
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to use for an incoming connection.  Equivalent to
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B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
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B<NoResumptionOnRenegotiation> set
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B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
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B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
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Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
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B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
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for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
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Set by default.
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=item B<VerifyMode>
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The B<value> argument is a comma separated list of flags to set.
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B<Peer> enables peer verification: for clients only.
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B<Request> requests but does not require a certificate from the client.
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Servers only.
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B<Require> requests and requires a certificate from the client: an error
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occurs if the client does not present a certificate. Servers only.
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B<Once> requests a certificate from a client only on the initial connection:
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not when renegotiating. Servers only.
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=item B<ClientCAFile>, B<ClientCAPath>
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A file or directory of certificates in PEM format whose names are used as the
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set of acceptable names for client CAs. Servers only. This option is only
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supported if certificate operations are permitted.
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=back
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=head1 SUPPORTED COMMAND TYPES
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The function SSL_CONF_cmd_value_type() currently returns one of the following
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types:
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=over 4
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=item B<SSL_CONF_TYPE_UNKNOWN>
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The B<cmd> string is unrecognised, this return value can be use to flag
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syntax errors.
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=item B<SSL_CONF_TYPE_STRING>
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The value is a string without any specific structure.
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=item B<SSL_CONF_TYPE_FILE>
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The value is a file name.
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=item B<SSL_CONF_TYPE_DIR>
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The value is a directory name.
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=item B<SSL_CONF_TYPE_NONE>
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The value string is not used e.g. a command line option which doesn't take an
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argument.
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=back
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=head1 NOTES
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The order of operations is significant. This can be used to set either defaults
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or values which cannot be overridden. For example if an application calls:
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 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
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 SSL_CONF_cmd(ctx, userparam, uservalue);
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it will disable SSLv3 support by default but the user can override it. If
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however the call sequence is:
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 SSL_CONF_cmd(ctx, userparam, uservalue);
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 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
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 | 
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SSLv3 is B<always> disabled and attempt to override this by the user are
 | 
						|
ignored.
 | 
						|
 | 
						|
By checking the return code of SSL_CTX_cmd() it is possible to query if a
 | 
						|
given B<cmd> is recognised, this is useful is SSL_CTX_cmd() values are
 | 
						|
mixed with additional application specific operations.
 | 
						|
 | 
						|
For example an application might call SSL_CTX_cmd() and if it returns
 | 
						|
-2 (unrecognised command) continue with processing of application specific
 | 
						|
commands.
 | 
						|
 | 
						|
Applications can also use SSL_CTX_cmd() to process command lines though the
 | 
						|
utility function SSL_CTX_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_CTX_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 procotols.
 | 
						|
 | 
						|
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");
 | 
						|
 | 
						|
Set automatic support for any elliptic curve for key exchange:
 | 
						|
 | 
						|
 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
 | 
						|
 | 
						|
=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.
 | 
						|
 | 
						|
SSL_CONF_finish() returns 1 for success and 0 for failure.
 | 
						|
 | 
						|
=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.
 | 
						|
 | 
						|
=cut
 |