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=pod
=head1 NAME
config - OpenSSL CONF library configuration files
=head1 DESCRIPTION
The OpenSSL CONF library can be used to read configuration files.
It is used for the OpenSSL master configuration file B<openssl.cnf>
and in a few other places like B<SPKAC> files and certificate extension
files for the B<x509> utility. OpenSSL applications can also use the
CONF library for their own purposes.
A configuration file is divided into a number of sections. Each section
starts with a line B<[ section_name ]> and ends when a new section is
started or end of file is reached. A section name can consist of
alphanumeric characters and underscores.
The first section of a configuration file is special and is referred
to as the B<default> section this is usually unnamed and is from the
start of file until the first named section. When a name is being looked up
it is first looked up in a named section (if any) and then the
default section.
The environment is mapped onto a section called B<ENV>.
Comments can be included by preceding them with the B<#> character
Each section in a configuration file consists of a number of name and
value pairs of the form B<name=value>
The B<name> string can contain any alphanumeric characters as well as
a few punctuation symbols such as B<.> B<,> B<;> and B<_>.
The B<value> string consists of the string following the B<=> character
until end of line with any leading and trailing white space removed.
The value string undergoes variable expansion. This can be done by
including the form B<$var> or B<${var}>: this will substitute the value
of the named variable in the current section. It is also possible to
substitute a value from another section using the syntax B<$section::name>
or B<${section::name}>. By using the form B<$ENV::name> environment
variables can be substituted. It is also possible to assign values to
environment variables by using the name B<ENV::name>, this will work
if the program looks up environment variables using the B<CONF> library
instead of calling getenv() directly. The value string must not exceed 64k in
length after variable expansion. Otherwise an error will occur.
It is possible to escape certain characters by using any kind of quote
or the B<\> character. By making the last character of a line a B<\>
a B<value> string can be spread across multiple lines. In addition
the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognized.
=head1 OPENSSL LIBRARY CONFIGURATION
Applications can automatically configure certain
aspects of OpenSSL using the master OpenSSL configuration file, or optionally
an alternative configuration file. The B<openssl> utility includes this
functionality: any sub command uses the master OpenSSL configuration file
unless an option is used in the sub command to use an alternative configuration
file.
To enable library configuration the default section needs to contain an
appropriate line which points to the main configuration section. The default
name is B<openssl_conf> which is used by the B<openssl> utility. Other
applications may use an alternative name such as B<myapplication_conf>.
All library configuration lines appear in the default section at the start
of the configuration file.
The configuration section should consist of a set of name value pairs which
contain specific module configuration information. The B<name> represents
the name of the I<configuration module> the meaning of the B<value> is
module specific: it may, for example, represent a further configuration
section containing configuration module specific information. E.g.
# This must be in the default section
openssl_conf = openssl_init
[openssl_init]
oid_section = new_oids
engines = engine_section
[new_oids]
... new oids here ...
[engine_section]
... engine stuff here ...
The features of each configuration module are described below.
=head2 ASN1 Object Configuration Module
This module has the name B<oid_section>. The value of this variable points
to a section containing name value pairs of OIDs: the name is the OID short
and long name, the value is the numerical form of the OID. Although some of
the B<openssl> utility sub commands already have their own ASN1 OBJECT section
functionality not all do. By using the ASN1 OBJECT configuration module
B<all> the B<openssl> utility sub commands can see the new objects as well
as any compliant applications. For example:
[new_oids]
some_new_oid = 1.2.3.4
some_other_oid = 1.2.3.5
It is also possible to set the value to the long name followed
by a comma and the numerical OID form. For example:
shortName = some object long name, 1.2.3.4
=head2 Engine Configuration Module
This ENGINE configuration module has the name B<engines>. The value of this
variable points to a section containing further ENGINE configuration
information.
The section pointed to by B<engines> is a table of engine names (though see
B<engine_id> below) and further sections containing configuration information
specific to each ENGINE.
Each ENGINE specific section is used to set default algorithms, load
dynamic, perform initialization and send ctrls. The actual operation performed
depends on the I<command> name which is the name of the name value pair. The
currently supported commands are listed below.
For example:
[engine_section]
# Configure ENGINE named "foo"
foo = foo_section
# Configure ENGINE named "bar"
bar = bar_section
[foo_section]
... foo ENGINE specific commands ...
[bar_section]
... "bar" ENGINE specific commands ...
The command B<engine_id> is used to give the ENGINE name. If used this
command must be first. For example:
[engine_section]
# This would normally handle an ENGINE named "foo"
foo = foo_section
[foo_section]
# Override default name and use "myfoo" instead.
engine_id = myfoo
The command B<dynamic_path> loads and adds an ENGINE from the given path. It
is equivalent to sending the ctrls B<SO_PATH> with the path argument followed
by B<LIST_ADD> with value 2 and B<LOAD> to the dynamic ENGINE. If this is
not the required behaviour then alternative ctrls can be sent directly
to the dynamic ENGINE using ctrl commands.
The command B<init> determines whether to initialize the ENGINE. If the value
is B<0> the ENGINE will not be initialized, if B<1> and attempt it made to
initialized the ENGINE immediately. If the B<init> command is not present
then an attempt will be made to initialize the ENGINE after all commands in
its section have been processed.
The command B<default_algorithms> sets the default algorithms an ENGINE will
supply using the functions ENGINE_set_default_string().
If the name matches none of the above command names it is assumed to be a
ctrl command which is sent to the ENGINE. The value of the command is the
argument to the ctrl command. If the value is the string B<EMPTY> then no
value is sent to the command.
For example:
[engine_section]
# Configure ENGINE named "foo"
foo = foo_section
[foo_section]
# Load engine from DSO
dynamic_path = /some/path/fooengine.so
# A foo specific ctrl.
some_ctrl = some_value
# Another ctrl that doesn't take a value.
other_ctrl = EMPTY
# Supply all default algorithms
default_algorithms = ALL
=head2 EVP Configuration Module
This modules has the name B<alg_section> which points to a section containing
algorithm commands.
Currently the only algorithm command supported is B<fips_mode> whose
value can only be the boolean string B<off>. If B<fips_mode> is set to B<on>,
an error occurs as this library version is not FIPS capable.
=head2 SSL Configuration Module
This module has the name B<ssl_conf> which points to a section containing
SSL configurations.
Each line in the SSL configuration section contains the name of the
configuration and the section containing it.
Each configuration section consists of command value pairs for B<SSL_CONF>.
Each pair will be passed to a B<SSL_CTX> or B<SSL> structure if it calls
SSL_CTX_config() or SSL_config() with the appropriate configuration name.
Note: any characters before an initial dot in the configuration section are
ignored so the same command can be used multiple times.
For example:
ssl_conf = ssl_sect
[ssl_sect]
server = server_section
[server_section]
RSA.Certificate = server-rsa.pem
ECDSA.Certificate = server-ecdsa.pem
Ciphers = ALL:!RC4
=head1 NOTES
If a configuration file attempts to expand a variable that doesn't exist
then an error is flagged and the file will not load. This can happen
if an attempt is made to expand an environment variable that doesn't
exist. For example in a previous version of OpenSSL the default OpenSSL
master configuration file used the value of B<HOME> which may not be
defined on non Unix systems and would cause an error.
This can be worked around by including a B<default> section to provide
a default value: then if the environment lookup fails the default value
will be used instead. For this to work properly the default value must
be defined earlier in the configuration file than the expansion. See
the B<EXAMPLES> section for an example of how to do this.
If the same variable exists in the same section then all but the last
value will be silently ignored. In certain circumstances such as with
DNs the same field may occur multiple times. This is usually worked
around by ignoring any characters before an initial B<.> e.g.
1.OU="My first OU"
2.OU="My Second OU"
=head1 EXAMPLES
Here is a sample configuration file using some of the features
mentioned above.
# This is the default section.
HOME=/temp
RANDFILE= ${ENV::HOME}/.rnd
configdir=$ENV::HOME/config
[ section_one ]
# We are now in section one.
# Quotes permit leading and trailing whitespace
any = " any variable name "
other = A string that can \
cover several lines \
by including \\ characters
message = Hello World\n
[ section_two ]
greeting = $section_one::message
This next example shows how to expand environment variables safely.
Suppose you want a variable called B<tmpfile> to refer to a
temporary filename. The directory it is placed in can determined by
the B<TEMP> or B<TMP> environment variables but they may not be
set to any value at all. If you just include the environment variable
names and the variable doesn't exist then this will cause an error when
an attempt is made to load the configuration file. By making use of the
default section both values can be looked up with B<TEMP> taking
priority and B</tmp> used if neither is defined:
TMP=/tmp
# The above value is used if TMP isn't in the environment
TEMP=$ENV::TMP
# The above value is used if TEMP isn't in the environment
tmpfile=${ENV::TEMP}/tmp.filename
Simple OpenSSL library configuration example to enter FIPS mode:
# Default appname: should match "appname" parameter (if any)
# supplied to CONF_modules_load_file et al.
openssl_conf = openssl_conf_section
[openssl_conf_section]
# Configuration module list
alg_section = evp_sect
[evp_sect]
# Set to "yes" to enter FIPS mode if supported
fips_mode = yes
Note: in the above example you will get an error in non FIPS capable versions
of OpenSSL.
More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:
# Default appname: should match "appname" parameter (if any)
# supplied to CONF_modules_load_file et al.
openssl_conf = openssl_conf_section
[openssl_conf_section]
# Configuration module list
alg_section = evp_sect
oid_section = new_oids
[evp_sect]
# This will have no effect as FIPS mode is off by default.
# Set to "yes" to enter FIPS mode, if supported
fips_mode = no
[new_oids]
# New OID, just short name
newoid1 = 1.2.3.4.1
# New OID shortname and long name
newoid2 = New OID 2 long name, 1.2.3.4.2
The above examples can be used with any application supporting library
configuration if "openssl_conf" is modified to match the appropriate "appname".
For example if the second sample file above is saved to "example.cnf" then
the command line:
OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1
will output:
0:d=0 hl=2 l= 4 prim: OBJECT :newoid1
showing that the OID "newoid1" has been added as "1.2.3.4.1".
=head1 BUGS
Currently there is no way to include characters using the octal B<\nnn>
form. Strings are all null terminated so nulls cannot form part of
the value.
The escaping isn't quite right: if you want to use sequences like B<\n>
you can't use any quote escaping on the same line.
Files are loaded in a single pass. This means that an variable expansion
will only work if the variables referenced are defined earlier in the
file.
=head1 SEE ALSO
L<x509(1)>, L<req(1)>, L<ca(1)>
=head1 COPYRIGHT
Copyright 2000-2016 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
doc/man5/x509v3_config.pod
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=pod
=head1 NAME
x509v3_config - X509 V3 certificate extension configuration format
=head1 DESCRIPTION
Several of the OpenSSL utilities can add extensions to a certificate or
certificate request based on the contents of a configuration file.
Typically the application will contain an option to point to an extension
section. Each line of the extension section takes the form:
extension_name=[critical,] extension_options
If B<critical> is present then the extension will be critical.
The format of B<extension_options> depends on the value of B<extension_name>.
There are four main types of extension: I<string> extensions, I<multi-valued>
extensions, I<raw> and I<arbitrary> extensions.
String extensions simply have a string which contains either the value itself
or how it is obtained.
For example:
nsComment="This is a Comment"
Multi-valued extensions have a short form and a long form. The short form
is a list of names and values:
basicConstraints=critical,CA:true,pathlen:1
The long form allows the values to be placed in a separate section:
basicConstraints=critical,@bs_section
[bs_section]
CA=true
pathlen=1
Both forms are equivalent.
The syntax of raw extensions is governed by the extension code: it can
for example contain data in multiple sections. The correct syntax to
use is defined by the extension code itself: check out the certificate
policies extension for an example.
If an extension type is unsupported then the I<arbitrary> extension syntax
must be used, see the L<ARBITRARY EXTENSIONS|/"ARBITRARY EXTENSIONS"> section for more details.
=head1 STANDARD EXTENSIONS
The following sections describe each supported extension in detail.
=head2 Basic Constraints.
This is a multi valued extension which indicates whether a certificate is
a CA certificate. The first (mandatory) name is B<CA> followed by B<TRUE> or
B<FALSE>. If B<CA> is B<TRUE> then an optional B<pathlen> name followed by an
non-negative value can be included.
For example:
basicConstraints=CA:TRUE
basicConstraints=CA:FALSE
basicConstraints=critical,CA:TRUE, pathlen:0
A CA certificate B<must> include the basicConstraints value with the CA field
set to TRUE. An end user certificate must either set CA to FALSE or exclude the
extension entirely. Some software may require the inclusion of basicConstraints
with CA set to FALSE for end entity certificates.
The pathlen parameter indicates the maximum number of CAs that can appear
below this one in a chain. So if you have a CA with a pathlen of zero it can
only be used to sign end user certificates and not further CAs.
=head2 Key Usage.
Key usage is a multi valued extension consisting of a list of names of the
permitted key usages.
The supported names are: digitalSignature, nonRepudiation, keyEncipherment,
dataEncipherment, keyAgreement, keyCertSign, cRLSign, encipherOnly
and decipherOnly.
Examples:
keyUsage=digitalSignature, nonRepudiation
keyUsage=critical, keyCertSign
=head2 Extended Key Usage.
This extensions consists of a list of usages indicating purposes for which
the certificate public key can be used for,
These can either be object short names or the dotted numerical form of OIDs.
While any OID can be used only certain values make sense. In particular the
following PKIX, NS and MS values are meaningful:
Value Meaning
----- -------
serverAuth SSL/TLS Web Server Authentication.
clientAuth SSL/TLS Web Client Authentication.
codeSigning Code signing.
emailProtection E-mail Protection (S/MIME).
timeStamping Trusted Timestamping
OCSPSigning OCSP Signing
ipsecIKE ipsec Internet Key Exchange
msCodeInd Microsoft Individual Code Signing (authenticode)
msCodeCom Microsoft Commercial Code Signing (authenticode)
msCTLSign Microsoft Trust List Signing
msEFS Microsoft Encrypted File System
Examples:
extendedKeyUsage=critical,codeSigning,1.2.3.4
extendedKeyUsage=serverAuth,clientAuth
=head2 Subject Key Identifier.
This is really a string extension and can take two possible values. Either
the word B<hash> which will automatically follow the guidelines in RFC3280
or a hex string giving the extension value to include. The use of the hex
string is strongly discouraged.
Example:
subjectKeyIdentifier=hash
=head2 Authority Key Identifier.
The authority key identifier extension permits two options. keyid and issuer:
both can take the optional value "always".
If the keyid option is present an attempt is made to copy the subject key
identifier from the parent certificate. If the value "always" is present
then an error is returned if the option fails.
The issuer option copies the issuer and serial number from the issuer
certificate. This will only be done if the keyid option fails or
is not included unless the "always" flag will always include the value.
Example:
authorityKeyIdentifier=keyid,issuer
=head2 Subject Alternative Name.
The subject alternative name extension allows various literal values to be
included in the configuration file. These include B<email> (an email address)
B<URI> a uniform resource indicator, B<DNS> (a DNS domain name), B<RID> (a
registered ID: OBJECT IDENTIFIER), B<IP> (an IP address), B<dirName>
(a distinguished name) and otherName.
The email option include a special 'copy' value. This will automatically
include any email addresses contained in the certificate subject name in
the extension.
The IP address used in the B<IP> options can be in either IPv4 or IPv6 format.
The value of B<dirName> should point to a section containing the distinguished
name to use as a set of name value pairs. Multi values AVAs can be formed by
prefacing the name with a B<+> character.
otherName can include arbitrary data associated with an OID: the value
should be the OID followed by a semicolon and the content in standard
L<ASN1_generate_nconf(3)> format.
Examples:
subjectAltName=email:copy,email:my@other.address,URI:http://my.url.here/
subjectAltName=IP:192.168.7.1
subjectAltName=IP:13::17
subjectAltName=email:my@other.address,RID:1.2.3.4
subjectAltName=otherName:1.2.3.4;UTF8:some other identifier
subjectAltName=dirName:dir_sect
[dir_sect]
C=UK
O=My Organization
OU=My Unit
CN=My Name
=head2 Issuer Alternative Name.
The issuer alternative name option supports all the literal options of
subject alternative name. It does B<not> support the email:copy option because
that would not make sense. It does support an additional issuer:copy option
that will copy all the subject alternative name values from the issuer
certificate (if possible).
Example:
issuerAltName = issuer:copy
=head2 Authority Info Access.
The authority information access extension gives details about how to access
certain information relating to the CA. Its syntax is accessOID;location
where I<location> has the same syntax as subject alternative name (except
that email:copy is not supported). accessOID can be any valid OID but only
certain values are meaningful, for example OCSP and caIssuers.
Example:
authorityInfoAccess = OCSP;URI:http://ocsp.my.host/
authorityInfoAccess = caIssuers;URI:http://my.ca/ca.html
=head2 CRL distribution points
This is a multi-valued extension whose options can be either in name:value pair
using the same form as subject alternative name or a single value representing
a section name containing all the distribution point fields.
For a name:value pair a new DistributionPoint with the fullName field set to
the given value both the cRLissuer and reasons fields are omitted in this case.
In the single option case the section indicated contains values for each
field. In this section:
If the name is "fullname" the value field should contain the full name
of the distribution point in the same format as subject alternative name.
If the name is "relativename" then the value field should contain a section
name whose contents represent a DN fragment to be placed in this field.
The name "CRLIssuer" if present should contain a value for this field in
subject alternative name format.
If the name is "reasons" the value field should consist of a comma
separated field containing the reasons. Valid reasons are: "keyCompromise",
"CACompromise", "affiliationChanged", "superseded", "cessationOfOperation",
"certificateHold", "privilegeWithdrawn" and "AACompromise".
Simple examples:
crlDistributionPoints=URI:http://myhost.com/myca.crl
crlDistributionPoints=URI:http://my.com/my.crl,URI:http://oth.com/my.crl
Full distribution point example:
crlDistributionPoints=crldp1_section
[crldp1_section]
fullname=URI:http://myhost.com/myca.crl
CRLissuer=dirName:issuer_sect
reasons=keyCompromise, CACompromise
[issuer_sect]
C=UK
O=Organisation
CN=Some Name
=head2 Issuing Distribution Point
This extension should only appear in CRLs. It is a multi valued extension
whose syntax is similar to the "section" pointed to by the CRL distribution
points extension with a few differences.
The names "reasons" and "CRLissuer" are not recognized.
The name "onlysomereasons" is accepted which sets this field. The value is
in the same format as the CRL distribution point "reasons" field.
The names "onlyuser", "onlyCA", "onlyAA" and "indirectCRL" are also accepted
the values should be a boolean value (TRUE or FALSE) to indicate the value of
the corresponding field.
Example:
issuingDistributionPoint=critical, @idp_section
[idp_section]
fullname=URI:http://myhost.com/myca.crl
indirectCRL=TRUE
onlysomereasons=keyCompromise, CACompromise
[issuer_sect]
C=UK
O=Organisation
CN=Some Name
=head2 Certificate Policies.
This is a I<raw> extension. All the fields of this extension can be set by
using the appropriate syntax.
If you follow the PKIX recommendations and just using one OID then you just
include the value of that OID. Multiple OIDs can be set separated by commas,
for example:
certificatePolicies= 1.2.4.5, 1.1.3.4
If you wish to include qualifiers then the policy OID and qualifiers need to
be specified in a separate section: this is done by using the @section syntax
instead of a literal OID value.
The section referred to must include the policy OID using the name
policyIdentifier, cPSuri qualifiers can be included using the syntax:
CPS.nnn=value
userNotice qualifiers can be set using the syntax:
userNotice.nnn=@notice
The value of the userNotice qualifier is specified in the relevant section.
This section can include explicitText, organization and noticeNumbers
options. explicitText and organization are text strings, noticeNumbers is a
comma separated list of numbers. The organization and noticeNumbers options
(if included) must BOTH be present. If you use the userNotice option with IE5
then you need the 'ia5org' option at the top level to modify the encoding:
otherwise it will not be interpreted properly.
Example:
certificatePolicies=ia5org,1.2.3.4,1.5.6.7.8,@polsect
[polsect]
policyIdentifier = 1.3.5.8
CPS.1="http://my.host.name/"
CPS.2="http://my.your.name/"
userNotice.1=@notice
[notice]
explicitText="Explicit Text Here"
organization="Organisation Name"
noticeNumbers=1,2,3,4
The B<ia5org> option changes the type of the I<organization> field. In RFC2459
it can only be of type DisplayText. In RFC3280 IA5String is also permissible.
Some software (for example some versions of MSIE) may require ia5org.
ASN1 type of explicitText can be specified by prepending B<UTF8>,
B<BMP> or B<VISIBLE> prefix followed by colon. For example:
[notice]
explicitText="UTF8:Explicit Text Here"
=head2 Policy Constraints
This is a multi-valued extension which consisting of the names
B<requireExplicitPolicy> or B<inhibitPolicyMapping> and a non negative integer
value. At least one component must be present.
Example:
policyConstraints = requireExplicitPolicy:3
=head2 Inhibit Any Policy
This is a string extension whose value must be a non negative integer.
Example:
inhibitAnyPolicy = 2
=head2 Name Constraints
The name constraints extension is a multi-valued extension. The name should
begin with the word B<permitted> or B<excluded> followed by a B<;>. The rest of
the name and the value follows the syntax of subjectAltName except email:copy
is not supported and the B<IP> form should consist of an IP addresses and
subnet mask separated by a B</>.
Examples:
nameConstraints=permitted;IP:192.168.0.0/255.255.0.0
nameConstraints=permitted;email:.somedomain.com
nameConstraints=excluded;email:.com
=head2 OCSP No Check
The OCSP No Check extension is a string extension but its value is ignored.
Example:
noCheck = ignored
=head2 TLS Feature (aka Must Staple)
This is a multi-valued extension consisting of a list of TLS extension
identifiers. Each identifier may be a number (0..65535) or a supported name.
When a TLS client sends a listed extension, the TLS server is expected to
include that extension in its reply.
The supported names are: B<status_request> and B<status_request_v2>.
Example:
tlsfeature = status_request
=head1 DEPRECATED EXTENSIONS
The following extensions are non standard, Netscape specific and largely
obsolete. Their use in new applications is discouraged.
=head2 Netscape String extensions.
Netscape Comment (B<nsComment>) is a string extension containing a comment
which will be displayed when the certificate is viewed in some browsers.
Example:
nsComment = "Some Random Comment"
Other supported extensions in this category are: B<nsBaseUrl>,
B<nsRevocationUrl>, B<nsCaRevocationUrl>, B<nsRenewalUrl>, B<nsCaPolicyUrl>
and B<nsSslServerName>.
=head2 Netscape Certificate Type
This is a multi-valued extensions which consists of a list of flags to be
included. It was used to indicate the purposes for which a certificate could
be used. The basicConstraints, keyUsage and extended key usage extensions are
now used instead.
Acceptable values for nsCertType are: B<client>, B<server>, B<email>,
B<objsign>, B<reserved>, B<sslCA>, B<emailCA>, B<objCA>.
=head1 ARBITRARY EXTENSIONS
If an extension is not supported by the OpenSSL code then it must be encoded
using the arbitrary extension format. It is also possible to use the arbitrary
format for supported extensions. Extreme care should be taken to ensure that
the data is formatted correctly for the given extension type.
There are two ways to encode arbitrary extensions.
The first way is to use the word ASN1 followed by the extension content
using the same syntax as L<ASN1_generate_nconf(3)>.
For example:
1.2.3.4=critical,ASN1:UTF8String:Some random data
1.2.3.4=ASN1:SEQUENCE:seq_sect
[seq_sect]
field1 = UTF8:field1
field2 = UTF8:field2
It is also possible to use the word DER to include the raw encoded data in any
extension.
1.2.3.4=critical,DER:01:02:03:04
1.2.3.4=DER:01020304
The value following DER is a hex dump of the DER encoding of the extension
Any extension can be placed in this form to override the default behaviour.
For example:
basicConstraints=critical,DER:00:01:02:03
=head1 WARNING
There is no guarantee that a specific implementation will process a given
extension. It may therefore be sometimes possible to use certificates for
purposes prohibited by their extensions because a specific application does
not recognize or honour the values of the relevant extensions.
The DER and ASN1 options should be used with caution. It is possible to create
totally invalid extensions if they are not used carefully.
=head1 NOTES
If an extension is multi-value and a field value must contain a comma the long
form must be used otherwise the comma would be misinterpreted as a field
separator. For example:
subjectAltName=URI:ldap://somehost.com/CN=foo,OU=bar
will produce an error but the equivalent form:
subjectAltName=@subject_alt_section
[subject_alt_section]
subjectAltName=URI:ldap://somehost.com/CN=foo,OU=bar
is valid.
Due to the behaviour of the OpenSSL B<conf> library the same field name
can only occur once in a section. This means that:
subjectAltName=@alt_section
[alt_section]
email=steve@here
email=steve@there
will only recognize the last value. This can be worked around by using the form:
[alt_section]
email.1=steve@here
email.2=steve@there
=head1 SEE ALSO
L<req(1)>, L<ca(1)>, L<x509(1)>,
L<ASN1_generate_nconf(3)>
=head1 COPYRIGHT
Copyright 2004-2016 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