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在用easy_rsa生成ovpn配置时，出现如下错误：
[ root: /usr/share/easy-rsa] #/usr/share/easy-rsa/build-key --batch zzzz.29761
Using Common Name: zzzz.29761
Generating a 2048 bit RSA private key
...............+++
.................................................................+++
writing new private key to 'zzzz.29761.key'
-----
Using configuration from /usr/share/easy-rsa/openssl-1.0.0.cnf
Error Loading extension section usr_cert
140516636624544:error:0E06D06C:configuration file routines:NCONF_get_string:no value:conf_lib.c:335:group=CA_default name=email_in_dn
140516636624544:error:2207507C:X509 V3 routines:v2i_GENERAL_NAME_ex:missing value:v3_alt.c:537:
140516636624544:error:22098080:X509 V3 routines:X509V3_EXT_nconf:error in extension:v3_conf.c:93:name=subjectAltName, value=zzzz.29761查看openvpn的版本信息：
# openvpn --version
OpenVPN 2.3.2 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [PKCS11] [eurephia] [MH] [IPv6] built on Dec 1 2014
Originally developed by James Yonan
Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>原因：
在配置文件openssl-1.0.0.cnf中，[usr_cert]节中多了参数： subjectAltName=email:copy，注释掉就OK了。
openssl-1.0.0.cnf内容：
[root@control 2.0]# cat openssl-1.0.0.cnf
# For use with easy-rsa version 2.0 and OpenSSL 1.0.0*# This definition stops the following lines choking if HOME isn't
# defined.
HOME = .
RANDFILE = $ENV::HOME/.rnd
openssl_conf = openssl_init[ openssl_init ]
# Extra OBJECT IDENTIFIER info:
#oid_file = $ENV::HOME/.oid
oid_section = new_oids
engines = engine_section# To use this configuration file with the "-extfile" option of the
# "openssl x509" utility, name here the section containing the
# X.509v3 extensions to use:
# extensions =
# (Alternatively, use a configuration file that has only
# X.509v3 extensions in its main [= default] section.)[ new_oids ]# We can add new OIDs in here for use by 'ca' and 'req'.
# Add a simple OID like this:
# testoid1=1.2.3.4
# Or use config file substitution like this:
# testoid2=${testoid1}.5.6####################################################################
[ ca ]
default_ca = CA_default # The default ca section####################################################################
[ CA_default ]dir = $ENV::KEY_DIR # Where everything is kept
certs = $dir # Where the issued certs are kept
crl_dir = $dir # Where the issued crl are kept
database = $dir/index.txt # database index file.
new_certs_dir = $dir # default place for new certs.certificate = $dir/ca.crt # The CA certificate
serial = $dir/serial # The current serial number
crl = $dir/crl.pem # The current CRL
private_key = $dir/ca.key # The private key
RANDFILE = $dir/.rand # private random number filex509_extensions = usr_cert # The extentions to add to the cert# Extensions to add to a CRL. Note: Netscape communicator chokes on V2 CRLs
# so this is commented out by default to leave a V1 CRL.
# crl_extensions = crl_extdefault_days = 3650 # how long to certify for
default_crl_days= 30 # how long before next CRL
default_md = sha256 # use public key default MD
preserve = no # keep passed DN ordering# A few difference way of specifying how similar the request should look
# For type CA, the listed attributes must be the same, and the optional
# and supplied fields are just that :-)
policy = policy_anything# For the CA policy
[ policy_match ]
countryName = match
stateOrProvinceName = match
organizationName = match
organizationalUnitName = optional
commonName = supplied
name = optional
emailAddress = optional# For the 'anything' policy
# At this point in time, you must list all acceptable 'object'
# types.
[ policy_anything ]
countryName = optional
stateOrProvinceName = optional
localityName = optional
organizationName = optional
organizationalUnitName = optional
commonName = supplied
name = optional
emailAddress = optional####################################################################
[ req ]
default_bits = $ENV::KEY_SIZE
default_keyfile = privkey.pem
default_md = sha256
distinguished_name = req_distinguished_name
attributes = req_attributes
x509_extensions = v3_ca # The extentions to add to the self signed cert# Passwords for private keys if not present they will be prompted for
# input_password = secret
# output_password = secret# This sets a mask for permitted string types. There are several options.
# default: PrintableString, T61String, BMPString.
# pkix : PrintableString, BMPString (PKIX recommendation after 2004).
# utf8only: only UTF8Strings (PKIX recommendation after 2004).
# nombstr : PrintableString, T61String (no BMPStrings or UTF8Strings).
# MASK:XXXX a literal mask value.
string_mask = nombstr# req_extensions = v3_req # The extensions to add to a certificate request[ req_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = $ENV::KEY_COUNTRY
countryName_min = 2
countryName_max = 2stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = $ENV::KEY_PROVINCElocalityName = Locality Name (eg, city)
localityName_default = $ENV::KEY_CITY0.organizationName = Organization Name (eg, company)
0.organizationName_default = $ENV::KEY_ORG# we can do this but it is not needed normally :-)
#1.organizationName = Second Organization Name (eg, company)
#1.organizationName_default = World Wide Web Pty LtdorganizationalUnitName = Organizational Unit Name (eg, section)
#organizationalUnitName_default =commonName = Common Name (eg, your name or your server\'s hostname)
commonName_max = 64name = Name
name_max = 64emailAddress = Email Address
emailAddress_default = $ENV::KEY_EMAIL
emailAddress_max = 40# JY -- added for batch mode
organizationalUnitName_default = $ENV::KEY_OU
commonName_default = $ENV::KEY_CN
name_default = $ENV::KEY_NAME# SET-ex3 = SET extension number 3[ req_attributes ]
challengePassword = A challenge password
challengePassword_min = 4
challengePassword_max = 20unstructuredName = An optional company name[ usr_cert ]# These extensions are added when 'ca' signs a request.# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.basicConstraints=CA:FALSE# Here are some examples of the usage of nsCertType. If it is omitted
# the certificate can be used for anything *except* object signing.# This is OK for an SSL server.
# nsCertType = server# For an object signing certificate this would be used.
# nsCertType = objsign# For normal client use this is typical
# nsCertType = client, email# and for everything including object signing:
# nsCertType = client, email, objsign# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment# This will be displayed in Netscape's comment listbox.
nsComment = "Easy-RSA Generated Certificate"# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer:always
extendedKeyUsage=clientAuth
keyUsage = digitalSignature# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy# Copy subject details
# issuerAltName=issuer:copy#nsCaRevocationUrl = http://www.domain.dom/ca-crl.pem
#nsBaseUrl
#nsRevocationUrl
#nsRenewalUrl
#nsCaPolicyUrl
#nsSslServerName[ server ]# JY ADDED -- Make a cert with nsCertType set to "server"
basicConstraints=CA:FALSE
nsCertType = server
nsComment = "Easy-RSA Generated Server Certificate"
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer:always
extendedKeyUsage=serverAuth
keyUsage = digitalSignature, keyEncipherment[ v3_req ]# Extensions to add to a certificate requestbasicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment[ v3_ca ]# Extensions for a typical CA# PKIX recommendation.subjectKeyIdentifier=hashauthorityKeyIdentifier=keyid:always,issuer:always# This is what PKIX recommends but some broken software chokes on critical
# extensions.
#basicConstraints = critical,CA:true
# So we do this instead.
basicConstraints = CA:true# Key usage: this is typical for a CA certificate. However since it will
# prevent it being used as an test self-signed certificate it is best
# left out by default.
# keyUsage = cRLSign, keyCertSign# Some might want this also
# nsCertType = sslCA, emailCA# Include email address in subject alt name: another PKIX recommendation
# subjectAltName=email:copy
# Copy issuer details
# issuerAltName=issuer:copy# DER hex encoding of an extension: beware experts only!
# obj=DER:02:03
# Where 'obj' is a standard or added object
# You can even override a supported extension:
# basicConstraints= critical, DER:30:03:01:01:FF[ crl_ext ]# CRL extensions.
# Only issuerAltName and authorityKeyIdentifier make any sense in a CRL.# issuerAltName=issuer:copy
authorityKeyIdentifier=keyid:always,issuer:always[ engine_section ]
#
# If you are using PKCS#11
# Install engine_pkcs11 of opensc (www.opensc.org)
# And uncomment the following
# verify that dynamic_path points to the correct location
#
#pkcs11 = pkcs11_section[ pkcs11_section ]
engine_id = pkcs11
dynamic_path = /usr/lib/engines/engine_pkcs11.so
MODULE_PATH = $ENV::PKCS11_MODULE_PATH
PIN = $ENV::PKCS11_PIN
init = 0参考：
1 Error Loading extension section usr_cert：http://stackoverflow.com/questions/24255205/error-loading-extension-section-usr-cert
2 openvpn配置文件详解：http://www-2w.blog.163.com/blog/static/9793151820111010253869/
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