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SSL_CONF_cmd(3) OpenSSL SSL_CONF_cmd(3)
NAME
SSL_CONF_cmd - send configuration command
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);
int SSL_CONF_finish(SSL_CONF_CTX *cctx);
DESCRIPTION
The function SSL_CONF_cmd() performs configuration operation cmd with optional parameter
value on ctx. Its purpose is to simplify application configuration of SSL_CTX or 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 cmd refers to.
The function SSL_CONF_finish() must be called after all configuration operations have been
completed. It is used to finalise any operations or to process defaults.
SUPPORTED COMMAND LINE COMMANDS
Currently supported cmd names for command lines (i.e. when the flag SSL_CONF_CMDLINE is
set) are listed below. Note: all cmd names are case sensitive. Unless otherwise stated
commands can be used by both clients and servers and the value parameter is not used. The
default prefix for command line commands is - and that is reflected below.
-sigalgs
This sets the supported signature algorithms for TLS v1.2. 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 value argument should be a colon separated list of signature algorithms in order
of decreasing preference of the form algorithm+hash. algorithm is one of RSA, DSA or
ECDSA and hash is a supported algorithm OID short name such as SHA1, SHA224, SHA256,
SHA384 of SHA512. Note: algorithm and hash names are case sensitive.
If this option is not set then all signature algorithms supported by the OpenSSL
library are permissible.
-client_sigalgs
This sets the supported signature algorithms associated with client authentication for
TLS v1.2. For servers the value is used in the supported signature algorithms field of
a certificate request. For clients it is used to determine which signature algorithm
to with the client certificate. If a server does not request a certificate this
option has no effect.
The syntax of value is identical to -sigalgs. If not set then the value set for
-sigalgs will be used instead.
-curves
This sets the supported elliptic curves. For clients the curves are sent using the
supported curves extension. For servers it is used to determine which curve to use.
This setting affects curves used for both signatures and key exchange, if applicable.
The value argument is a colon separated list of curves. The curve can be either the
NIST name (e.g. P-256) or an OpenSSL OID name (e.g prime256v1). Curve names are case
sensitive.
-named_curve
This sets the temporary curve used for ephemeral ECDH modes. Only used by servers
The value argument is a curve name or the special value auto which picks an
appropriate curve based on client and server preferences. The curve can be either the
NIST name (e.g. P-256) or an OpenSSL OID name (e.g prime256v1). Curve names are case
sensitive.
-cipher
Sets the cipher suite list to value. Note: syntax checking of value is currently not
performed unless a SSL or SSL_CTX structure is associated with cctx.
-cert
Attempts to use the file value as the certificate for the appropriate context. It
currently uses SSL_CTX_use_certificate_chain_file() if an SSL_CTX structure is set or
SSL_use_certificate_file() with filetype PEM if an SSL structure is set. This option
is only supported if certificate operations are permitted.
-key
Attempts to use the file value as the private key for the appropriate context. This
option is only supported if certificate operations are permitted. Note: if no -key
option is set then a private key is not loaded: it does not currently use the -cert
file.
-dhparam
Attempts to use the file value as the set of temporary DH parameters for the
appropriate context. This option is only supported if certificate operations are
permitted.
-no_ssl2, -no_ssl3, -no_tls1, -no_tls1_1, -no_tls1_2
Disables protocol support for SSLv2, SSLv3, TLSv1.0, TLSv1.1 or TLSv1.2 by setting the
corresponding options SSL_OP_NO_SSLv2, SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1,
SSL_OP_NO_TLSv1_1 and SSL_OP_NO_TLSv1_2 respectively.
-bugs
Various bug workarounds are set, same as setting SSL_OP_ALL.
-no_comp
Disables support for SSL/TLS compression, same as setting SSL_OP_NO_COMPRESS.
-no_ticket
Disables support for session tickets, same as setting SSL_OP_NO_TICKET.
-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 SSL_OP_CIPHER_SERVER_PREFERENCE. Only used by servers.
-no_resumption_on_reneg
set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
-legacyrenegotiation
permits the use of unsafe legacy renegotiation. Equivalent to setting
SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION.
-legacy_server_connect, -no_legacy_server_connect
permits or prohibits the use of unsafe legacy renegotiation for OpenSSL clients only.
Equivalent to setting or clearing SSL_OP_LEGACY_SERVER_CONNECT. Set by default.
-strict
enables strict mode protocol handling. Equivalent to setting SSL_CERT_FLAG_TLS_STRICT.
-debug_broken_protocol
disables various checks and permits several kinds of broken protocol behaviour for
testing purposes: it should NEVER be used in anything other than a test environment.
Only supported if OpenSSL is configured with -DOPENSSL_SSL_DEBUG_BROKEN_PROTOCOL.
SUPPORTED CONFIGURATION FILE COMMANDS
Currently supported cmd names for configuration files (i.e. when the flag
SSL_CONF_FLAG_FILE is set) are listed below. All configuration file cmd names and are case
insensitive so signaturealgorithms is recognised as well as SignatureAlgorithms. Unless
otherwise stated the value names are also case insensitive.
Note: the command prefix (if set) alters the recognised cmd values.
CipherString
Sets the cipher suite list to value. Note: syntax checking of value is currently not
performed unless an SSL or SSL_CTX structure is associated with cctx.
Certificate
Attempts to use the file value as the certificate for the appropriate context. It
currently uses SSL_CTX_use_certificate_chain_file() if an SSL_CTX structure is set or
SSL_use_certificate_file() with filetype PEM if an SSL structure is set. This option
is only supported if certificate operations are permitted.
PrivateKey
Attempts to use the file value as the private key for the appropriate context. This
option is only supported if certificate operations are permitted. Note: if no -key
option is set then a private key is not loaded: it does not currently use the
Certificate file.
ServerInfoFile
Attempts to use the file value in the "serverinfo" extension using the function
SSL_CTX_use_serverinfo_file.
DHParameters
Attempts to use the file value as the set of temporary DH parameters for the
appropriate context. This option is only supported if certificate operations are
permitted.
SignatureAlgorithms
This sets the supported signature algorithms for TLS v1.2. 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 value argument should be a colon separated list of signature algorithms in order
of decreasing preference of the form algorithm+hash. algorithm is one of RSA, DSA or
ECDSA and hash is a supported algorithm OID short name such as SHA1, SHA224, SHA256,
SHA384 of SHA512. Note: algorithm and hash names are case sensitive.
If this option is not set then all signature algorithms supported by the OpenSSL
library are permissible.
ClientSignatureAlgorithms
This sets the supported signature algorithms associated with client authentication for
TLS v1.2. For servers the value is used in the supported signature algorithms field of
a certificate request. For clients it is used to determine which signature algorithm
to with the client certificate.
The syntax of value is identical to SignatureAlgorithms. If not set then the value set
for SignatureAlgorithms will be used instead.
Curves
This sets the supported elliptic curves. For clients the curves are sent using the
supported curves extension. For servers it is used to determine which curve to use.
This setting affects curves used for both signatures and key exchange, if applicable.
The value argument is a colon separated list of curves. The curve can be either the
NIST name (e.g. P-256) or an OpenSSL OID name (e.g prime256v1). Curve names are case
sensitive.
ECDHParameters
This sets the temporary curve used for ephemeral ECDH modes. Only used by servers
The value argument is a curve name or the special value Automatic which picks an
appropriate curve based on client and server preferences. The curve can be either the
NIST name (e.g. P-256) or an OpenSSL OID name (e.g prime256v1). Curve names are case
sensitive.
Protocol
The supported versions of the SSL or TLS protocol.
The value argument is a comma separated list of supported protocols to enable or
disable. If an protocol is preceded by - that version is disabled. Currently
supported protocol values are SSLv2, SSLv3, TLSv1, TLSv1.1 and TLSv1.2. All protocol
versions other than SSLv2 are enabled by default. To avoid inadvertent enabling of
SSLv2, when SSLv2 is disabled, it is not possible to enable it via the Protocol
command.
Options
The value argument is a comma separated list of various flags to set. If a flag
string is preceded - it is disabled. See the SSL_CTX_set_options function for more
details of individual options.
Each option is listed below. Where an operation is enabled by default the -flag syntax
is needed to disable it.
SessionTicket: session ticket support, enabled by default. Inverse of
SSL_OP_NO_TICKET: that is -SessionTicket is the same as setting SSL_OP_NO_TICKET.
Compression: SSL/TLS compression support, enabled by default. Inverse of
SSL_OP_NO_COMPRESSION.
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
SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS.
Bugs: enable various bug workarounds. Same as SSL_OP_ALL.
DHSingle: enable single use DH keys, set by default. Inverse of SSL_OP_DH_SINGLE. Only
used by servers.
ECDHSingle enable single use ECDH keys, set by default. Inverse of SSL_OP_ECDH_SINGLE.
Only used by servers.
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 SSL_OP_CIPHER_SERVER_PREFERENCE. Only used by servers.
NoResumptionOnRenegotiation set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag.
Only used by servers.
UnsafeLegacyRenegotiation permits the use of unsafe legacy renegotiation. Equivalent
to SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION.
UnsafeLegacyServerConnect permits the use of unsafe legacy renegotiation for OpenSSL
clients only. Equivalent to SSL_OP_LEGACY_SERVER_CONNECT. Set by default.
SUPPORTED COMMAND TYPES
The function SSL_CONF_cmd_value_type() currently returns one of the following types:
SSL_CONF_TYPE_UNKNOWN
The cmd string is unrecognised, this return value can be use to flag syntax errors.
SSL_CONF_TYPE_STRING
The value is a string without any specific structure.
SSL_CONF_TYPE_FILE
The value is a file name.
SSL_CONF_TYPE_DIR
The value is a directory name.
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");
then SSLv3 is 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 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 cmd and the following argument to 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 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 SSL_CONF_TYPE_FILE an application could
translate a relative pathname to an absolute pathname.
EXAMPLES
Set supported signature algorithms:
SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
Enable all protocols except SSLv3 and SSLv2:
SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3,-SSLv2");
Only enable TLSv1.2:
SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
Disable TLS session tickets:
SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
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");
RETURN VALUES
SSL_CONF_cmd() returns 1 if the value of cmd is recognised and value is NOT used and 2 if
both cmd and 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 cmd is not recognised.
A return value of -3 means cmd is recognised and the command requires a value but value is
NULL.
A return code of 0 indicates that both cmd and value are valid but an error occurred
attempting to perform the operation: for example due to an error in the syntax of value in
this case the error queue may provide additional information.
SSL_CONF_finish() returns 1 for success and 0 for failure.
SEE ALSO
SSL_CONF_CTX_new(3), SSL_CONF_CTX_set_flags(3), SSL_CONF_CTX_set1_prefix(3),
SSL_CONF_CTX_set_ssl_ctx(3), SSL_CONF_cmd_argv(3)
HISTORY
SSL_CONF_cmd() was first added to OpenSSL 1.0.2
1.0.2k 2017-01-26 SSL_CONF_cmd(3)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2024-04-27 04:23 @18.221.187.121 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)