5 config - OpenSSL CONF library configuration files
9 The OpenSSL CONF library can be used to read configuration files.
10 It is used for the OpenSSL master configuration file B<openssl.cnf>
11 and in a few other places like B<SPKAC> files and certificate extension
12 files for the B<x509> utility. OpenSSL applications can also use the
13 CONF library for their own purposes.
15 A configuration file is divided into a number of sections. Each section
16 starts with a line B<[ section_name ]> and ends when a new section is
17 started or end of file is reached. A section name can consist of
18 alphanumeric characters and underscores.
20 The first section of a configuration file is special and is referred
21 to as the B<default> section this is usually unnamed and is from the
22 start of file until the first named section. When a name is being looked up
23 it is first looked up in a named section (if any) and then the
26 The environment is mapped onto a section called B<ENV>.
28 Comments can be included by preceding them with the B<#> character
30 Other files can be included using the B<.include> directive followed
31 by a path. If the path points to a directory all files with
32 names ending with B<.cnf> or B<.conf> are included from the directory.
33 Recursive inclusion of directories from files in such directory is not
34 supported. That means the files in the included directory can also contain
35 B<.include> directives but only inclusion of regular files is supported
36 there. The inclusion of directories is not supported on systems without
39 It is strongly recommended to use absolute paths with the B<.include>
40 directive. Relative paths are evaluated based on the application current
41 working directory so unless the configuration file containing the
42 B<.include> directive is application specific the inclusion will not
45 Each section in a configuration file consists of a number of name and
46 value pairs of the form B<name=value>
48 The B<name> string can contain any alphanumeric characters as well as
49 a few punctuation symbols such as B<.> B<,> B<;> and B<_>.
51 The B<value> string consists of the string following the B<=> character
52 until end of line with any leading and trailing white space removed.
54 The value string undergoes variable expansion. This can be done by
55 including the form B<$var> or B<${var}>: this will substitute the value
56 of the named variable in the current section. It is also possible to
57 substitute a value from another section using the syntax B<$section::name>
58 or B<${section::name}>. By using the form B<$ENV::name> environment
59 variables can be substituted. It is also possible to assign values to
60 environment variables by using the name B<ENV::name>, this will work
61 if the program looks up environment variables using the B<CONF> library
62 instead of calling getenv() directly. The value string must not exceed 64k in
63 length after variable expansion. Otherwise an error will occur.
65 It is possible to escape certain characters by using any kind of quote
66 or the B<\> character. By making the last character of a line a B<\>
67 a B<value> string can be spread across multiple lines. In addition
68 the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognized.
70 All expansion and escape rules as described above that apply to B<value>
71 also apply to the path of the B<.include> directive.
73 =head1 OPENSSL LIBRARY CONFIGURATION
75 Applications can automatically configure certain
76 aspects of OpenSSL using the master OpenSSL configuration file, or optionally
77 an alternative configuration file. The B<openssl> utility includes this
78 functionality: any sub command uses the master OpenSSL configuration file
79 unless an option is used in the sub command to use an alternative configuration
82 To enable library configuration the default section needs to contain an
83 appropriate line which points to the main configuration section. The default
84 name is B<openssl_conf> which is used by the B<openssl> utility. Other
85 applications may use an alternative name such as B<myapplication_conf>.
86 All library configuration lines appear in the default section at the start
87 of the configuration file.
89 The configuration section should consist of a set of name value pairs which
90 contain specific module configuration information. The B<name> represents
91 the name of the I<configuration module> the meaning of the B<value> is
92 module specific: it may, for example, represent a further configuration
93 section containing configuration module specific information. E.g.
95 # This must be in the default section
96 openssl_conf = openssl_init
100 oid_section = new_oids
101 engines = engine_section
105 ... new oids here ...
109 ... engine stuff here ...
111 The features of each configuration module are described below.
113 =head2 ASN1 Object Configuration Module
115 This module has the name B<oid_section>. The value of this variable points
116 to a section containing name value pairs of OIDs: the name is the OID short
117 and long name, the value is the numerical form of the OID. Although some of
118 the B<openssl> utility sub commands already have their own ASN1 OBJECT section
119 functionality not all do. By using the ASN1 OBJECT configuration module
120 B<all> the B<openssl> utility sub commands can see the new objects as well
121 as any compliant applications. For example:
125 some_new_oid = 1.2.3.4
126 some_other_oid = 1.2.3.5
128 It is also possible to set the value to the long name followed
129 by a comma and the numerical OID form. For example:
131 shortName = some object long name, 1.2.3.4
133 =head2 Engine Configuration Module
135 This ENGINE configuration module has the name B<engines>. The value of this
136 variable points to a section containing further ENGINE configuration
139 The section pointed to by B<engines> is a table of engine names (though see
140 B<engine_id> below) and further sections containing configuration information
141 specific to each ENGINE.
143 Each ENGINE specific section is used to set default algorithms, load
144 dynamic, perform initialization and send ctrls. The actual operation performed
145 depends on the I<command> name which is the name of the name value pair. The
146 currently supported commands are listed below.
152 # Configure ENGINE named "foo"
154 # Configure ENGINE named "bar"
158 ... foo ENGINE specific commands ...
161 ... "bar" ENGINE specific commands ...
163 The command B<engine_id> is used to give the ENGINE name. If used this
164 command must be first. For example:
167 # This would normally handle an ENGINE named "foo"
171 # Override default name and use "myfoo" instead.
174 The command B<dynamic_path> loads and adds an ENGINE from the given path. It
175 is equivalent to sending the ctrls B<SO_PATH> with the path argument followed
176 by B<LIST_ADD> with value 2 and B<LOAD> to the dynamic ENGINE. If this is
177 not the required behaviour then alternative ctrls can be sent directly
178 to the dynamic ENGINE using ctrl commands.
180 The command B<init> determines whether to initialize the ENGINE. If the value
181 is B<0> the ENGINE will not be initialized, if B<1> and attempt it made to
182 initialized the ENGINE immediately. If the B<init> command is not present
183 then an attempt will be made to initialize the ENGINE after all commands in
184 its section have been processed.
186 The command B<default_algorithms> sets the default algorithms an ENGINE will
187 supply using the functions ENGINE_set_default_string().
189 If the name matches none of the above command names it is assumed to be a
190 ctrl command which is sent to the ENGINE. The value of the command is the
191 argument to the ctrl command. If the value is the string B<EMPTY> then no
192 value is sent to the command.
199 # Configure ENGINE named "foo"
203 # Load engine from DSO
204 dynamic_path = /some/path/fooengine.so
205 # A foo specific ctrl.
206 some_ctrl = some_value
207 # Another ctrl that doesn't take a value.
209 # Supply all default algorithms
210 default_algorithms = ALL
212 =head2 EVP Configuration Module
214 This modules has the name B<alg_section> which points to a section containing
217 Currently the only algorithm command supported is B<fips_mode> whose
218 value can only be the boolean string B<off>. If B<fips_mode> is set to B<on>,
219 an error occurs as this library version is not FIPS capable.
221 =head2 SSL Configuration Module
223 This module has the name B<ssl_conf> which points to a section containing
226 Each line in the SSL configuration section contains the name of the
227 configuration and the section containing it.
229 Each configuration section consists of command value pairs for B<SSL_CONF>.
230 Each pair will be passed to a B<SSL_CTX> or B<SSL> structure if it calls
231 SSL_CTX_config() or SSL_config() with the appropriate configuration name.
233 Note: any characters before an initial dot in the configuration section are
234 ignored so the same command can be used multiple times.
242 server = server_section
246 RSA.Certificate = server-rsa.pem
247 ECDSA.Certificate = server-ecdsa.pem
250 The system default configuration with name B<system_default> if present will
251 be applied during any creation of the B<SSL_CTX> structure.
253 Example of a configuration with the system default:
259 system_default = system_default_sect
261 [system_default_sect]
263 MinProtocol = TLSv1.2
268 If a configuration file attempts to expand a variable that doesn't exist
269 then an error is flagged and the file will not load. This can happen
270 if an attempt is made to expand an environment variable that doesn't
271 exist. For example in a previous version of OpenSSL the default OpenSSL
272 master configuration file used the value of B<HOME> which may not be
273 defined on non Unix systems and would cause an error.
275 This can be worked around by including a B<default> section to provide
276 a default value: then if the environment lookup fails the default value
277 will be used instead. For this to work properly the default value must
278 be defined earlier in the configuration file than the expansion. See
279 the B<EXAMPLES> section for an example of how to do this.
281 If the same variable exists in the same section then all but the last
282 value will be silently ignored. In certain circumstances such as with
283 DNs the same field may occur multiple times. This is usually worked
284 around by ignoring any characters before an initial B<.> e.g.
291 Here is a sample configuration file using some of the features
294 # This is the default section.
297 RANDFILE= ${ENV::HOME}/.rnd
298 configdir=$ENV::HOME/config
302 # We are now in section one.
304 # Quotes permit leading and trailing whitespace
305 any = " any variable name "
307 other = A string that can \
308 cover several lines \
309 by including \\ characters
311 message = Hello World\n
315 greeting = $section_one::message
317 This next example shows how to expand environment variables safely.
319 Suppose you want a variable called B<tmpfile> to refer to a
320 temporary filename. The directory it is placed in can determined by
321 the B<TEMP> or B<TMP> environment variables but they may not be
322 set to any value at all. If you just include the environment variable
323 names and the variable doesn't exist then this will cause an error when
324 an attempt is made to load the configuration file. By making use of the
325 default section both values can be looked up with B<TEMP> taking
326 priority and B</tmp> used if neither is defined:
329 # The above value is used if TMP isn't in the environment
331 # The above value is used if TEMP isn't in the environment
332 tmpfile=${ENV::TEMP}/tmp.filename
334 Simple OpenSSL library configuration example to enter FIPS mode:
336 # Default appname: should match "appname" parameter (if any)
337 # supplied to CONF_modules_load_file et al.
338 openssl_conf = openssl_conf_section
340 [openssl_conf_section]
341 # Configuration module list
342 alg_section = evp_sect
345 # Set to "yes" to enter FIPS mode if supported
348 Note: in the above example you will get an error in non FIPS capable versions
351 More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:
353 # Default appname: should match "appname" parameter (if any)
354 # supplied to CONF_modules_load_file et al.
355 openssl_conf = openssl_conf_section
357 [openssl_conf_section]
358 # Configuration module list
359 alg_section = evp_sect
360 oid_section = new_oids
363 # This will have no effect as FIPS mode is off by default.
364 # Set to "yes" to enter FIPS mode, if supported
368 # New OID, just short name
370 # New OID shortname and long name
371 newoid2 = New OID 2 long name, 1.2.3.4.2
373 The above examples can be used with any application supporting library
374 configuration if "openssl_conf" is modified to match the appropriate "appname".
376 For example if the second sample file above is saved to "example.cnf" then
379 OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1
383 0:d=0 hl=2 l= 4 prim: OBJECT :newoid1
385 showing that the OID "newoid1" has been added as "1.2.3.4.1".
389 Currently there is no way to include characters using the octal B<\nnn>
390 form. Strings are all null terminated so nulls cannot form part of
393 The escaping isn't quite right: if you want to use sequences like B<\n>
394 you can't use any quote escaping on the same line.
396 Files are loaded in a single pass. This means that an variable expansion
397 will only work if the variables referenced are defined earlier in the
402 L<x509(1)>, L<req(1)>, L<ca(1)>
406 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
408 Licensed under the OpenSSL license (the "License"). You may not use
409 this file except in compliance with the License. You can obtain a copy
410 in the file LICENSE in the source distribution or at
411 L<https://www.openssl.org/source/license.html>.