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 Each section in a configuration file consists of a number of name and
31 value pairs of the form B<name=value>
33 The B<name> string can contain any alphanumeric characters as well as
34 a few punctuation symbols such as B<.> B<,> B<;> and B<_>.
36 The B<value> string consists of the string following the B<=> character
37 until end of line with any leading and trailing white space removed.
39 The value string undergoes variable expansion. This can be done by
40 including the form B<$var> or B<${var}>: this will substitute the value
41 of the named variable in the current section. It is also possible to
42 substitute a value from another section using the syntax B<$section::name>
43 or B<${section::name}>. By using the form B<$ENV::name> environment
44 variables can be substituted. It is also possible to assign values to
45 environment variables by using the name B<ENV::name>, this will work
46 if the program looks up environment variables using the B<CONF> library
47 instead of calling getenv() directly.
49 It is possible to escape certain characters by using any kind of quote
50 or the B<\> character. By making the last character of a line a B<\>
51 a B<value> string can be spread across multiple lines. In addition
52 the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognized.
54 =head1 OPENSSL LIBRARY CONFIGURATION
56 Applications can automatically configure certain
57 aspects of OpenSSL using the master OpenSSL configuration file, or optionally
58 an alternative configuration file. The B<openssl> utility includes this
59 functionality: any sub command uses the master OpenSSL configuration file
60 unless an option is used in the sub command to use an alternative configuration
63 To enable library configuration the default section needs to contain an
64 appropriate line which points to the main configuration section. The default
65 name is B<openssl_conf> which is used by the B<openssl> utility. Other
66 applications may use an alternative name such as B<myapplicaton_conf>.
68 The configuration section should consist of a set of name value pairs which
69 contain specific module configuration information. The B<name> represents
70 the name of the I<configuration module> the meaning of the B<value> is
71 module specific: it may, for example, represent a further configuration
72 section containing configuration module specific information. E.g.
74 openssl_conf = openssl_init
78 oid_section = new_oids
79 engines = engine_section
87 ... engine stuff here ...
89 The features of each configuration module are described below.
91 =head2 ASN1 Object Configuration Module
93 This module has the name B<oid_section>. The value of this variable points
94 to a section containing name value pairs of OIDs: the name is the OID short
95 and long name, the value is the numerical form of the OID. Although some of
96 the B<openssl> utility sub commands already have their own ASN1 OBJECT section
97 functionality not all do. By using the ASN1 OBJECT configuration module
98 B<all> the B<openssl> utility sub commands can see the new objects as well
99 as any compliant applications. For example:
103 some_new_oid = 1.2.3.4
104 some_other_oid = 1.2.3.5
106 It is also possible to set the value to the long name followed
107 by a comma and the numerical OID form. For example:
109 shortName = some object long name, 1.2.3.4
111 =head2 Engine Configuration Module
113 This ENGINE configuration module has the name B<engines>. The value of this
114 variable points to a section containing further ENGINE configuration
117 The section pointed to by B<engines> is a table of engine names (though see
118 B<engine_id> below) and further sections containing configuration information
119 specific to each ENGINE.
121 Each ENGINE specific section is used to set default algorithms, load
122 dynamic, perform initialization and send ctrls. The actual operation performed
123 depends on the I<command> name which is the name of the name value pair. The
124 currently supported commands are listed below.
130 # Configure ENGINE named "foo"
132 # Configure ENGINE named "bar"
136 ... foo ENGINE specific commands ...
139 ... "bar" ENGINE specific commands ...
141 The command B<engine_id> is used to give the ENGINE name. If used this
142 command must be first. For example:
145 # This would normally handle an ENGINE named "foo"
149 # Override default name and use "myfoo" instead.
152 The command B<dynamic_path> loads and adds an ENGINE from the given path. It
153 is equivalent to sending the ctrls B<SO_PATH> with the path argument followed
154 by B<LIST_ADD> with value 2 and B<LOAD> to the dynamic ENGINE. If this is
155 not the required behaviour then alternative ctrls can be sent directly
156 to the dynamic ENGINE using ctrl commands.
158 The command B<init> determines whether to initialize the ENGINE. If the value
159 is B<0> the ENGINE will not be initialized, if B<1> and attempt it made to
160 initialized the ENGINE immediately. If the B<init> command is not present
161 then an attempt will be made to initialize the ENGINE after all commands in
162 its section have been processed.
164 The command B<default_algorithms> sets the default algorithms an ENGINE will
165 supply using the functions ENGINE_set_default_string().
167 If the name matches none of the above command names it is assumed to be a
168 ctrl command which is sent to the ENGINE. The value of the command is the
169 argument to the ctrl command. If the value is the string B<EMPTY> then no
170 value is sent to the command.
177 # Configure ENGINE named "foo"
181 # Load engine from DSO
182 dynamic_path = /some/path/fooengine.so
183 # A foo specific ctrl.
184 some_ctrl = some_value
185 # Another ctrl that doesn't take a value.
187 # Supply all default algorithms
188 default_algorithms = ALL
190 =head2 EVP Configuration Module
192 This modules has the name B<alg_section> which points to a section containing
195 Currently the only algorithm command supported is B<fips_mode> whose
196 value can only be the boolean string B<off>. If B<fips_mode> is set to B<on>,
197 an error occurs as this library version is not FIPS capable.
199 =head2 SSL Configuration Module
201 This module has the name B<ssl_conf> which points to a section containing
204 Each line in the SSL configuration section contains the name of the
205 configuration and the section containing it.
207 Each configuration section consists of command value pairs for B<SSL_CONF>.
208 Each pair will be passed to a B<SSL_CTX> or B<SSL> structure if it calls
209 SSL_CTX_config() or SSL_config() with the appropriate configuration name.
211 Note: any characters before an initial dot in the configuration section are
212 ignored so the same command can be used multiple times.
220 server = server_section
224 RSA.Certificate = server-rsa.pem
225 ECDSA.Certificate = server-ecdsa.pem
230 If a configuration file attempts to expand a variable that doesn't exist
231 then an error is flagged and the file will not load. This can happen
232 if an attempt is made to expand an environment variable that doesn't
233 exist. For example in a previous version of OpenSSL the default OpenSSL
234 master configuration file used the value of B<HOME> which may not be
235 defined on non Unix systems and would cause an error.
237 This can be worked around by including a B<default> section to provide
238 a default value: then if the environment lookup fails the default value
239 will be used instead. For this to work properly the default value must
240 be defined earlier in the configuration file than the expansion. See
241 the B<EXAMPLES> section for an example of how to do this.
243 If the same variable exists in the same section then all but the last
244 value will be silently ignored. In certain circumstances such as with
245 DNs the same field may occur multiple times. This is usually worked
246 around by ignoring any characters before an initial B<.> e.g.
253 Here is a sample configuration file using some of the features
256 # This is the default section.
259 RANDFILE= ${ENV::HOME}/.rnd
260 configdir=$ENV::HOME/config
264 # We are now in section one.
266 # Quotes permit leading and trailing whitespace
267 any = " any variable name "
269 other = A string that can \
270 cover several lines \
271 by including \\ characters
273 message = Hello World\n
277 greeting = $section_one::message
279 This next example shows how to expand environment variables safely.
281 Suppose you want a variable called B<tmpfile> to refer to a
282 temporary filename. The directory it is placed in can determined by
283 the B<TEMP> or B<TMP> environment variables but they may not be
284 set to any value at all. If you just include the environment variable
285 names and the variable doesn't exist then this will cause an error when
286 an attempt is made to load the configuration file. By making use of the
287 default section both values can be looked up with B<TEMP> taking
288 priority and B</tmp> used if neither is defined:
291 # The above value is used if TMP isn't in the environment
293 # The above value is used if TEMP isn't in the environment
294 tmpfile=${ENV::TEMP}/tmp.filename
296 Simple OpenSSL library configuration example to enter FIPS mode:
298 # Default appname: should match "appname" parameter (if any)
299 # supplied to CONF_modules_load_file et al.
300 openssl_conf = openssl_conf_section
302 [openssl_conf_section]
303 # Configuration module list
304 alg_section = evp_sect
307 # Set to "yes" to enter FIPS mode if supported
310 Note: in the above example you will get an error in non FIPS capable versions
313 More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:
315 # Default appname: should match "appname" parameter (if any)
316 # supplied to CONF_modules_load_file et al.
317 openssl_conf = openssl_conf_section
319 [openssl_conf_section]
320 # Configuration module list
321 alg_section = evp_sect
322 oid_section = new_oids
325 # This will have no effect as FIPS mode is off by default.
326 # Set to "yes" to enter FIPS mode, if supported
330 # New OID, just short name
332 # New OID shortname and long name
333 newoid2 = New OID 2 long name, 1.2.3.4.2
335 The above examples can be used with any application supporting library
336 configuration if "openssl_conf" is modified to match the appropriate "appname".
338 For example if the second sample file above is saved to "example.cnf" then
341 OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1
345 0:d=0 hl=2 l= 4 prim: OBJECT :newoid1
347 showing that the OID "newoid1" has been added as "1.2.3.4.1".
351 Currently there is no way to include characters using the octal B<\nnn>
352 form. Strings are all null terminated so nulls cannot form part of
355 The escaping isn't quite right: if you want to use sequences like B<\n>
356 you can't use any quote escaping on the same line.
358 Files are loaded in a single pass. This means that an variable expansion
359 will only work if the variables referenced are defined earlier in the
364 L<x509(1)>, L<req(1)>, L<ca(1)>
368 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
370 Licensed under the OpenSSL license (the "License"). You may not use
371 this file except in compliance with the License. You can obtain a copy
372 in the file LICENSE in the source distribution or at
373 L<https://www.openssl.org/source/license.html>.