环境：
CentOS 6.8 x86_64
安装
openssl openssl-devel
cp /etc/pki/tls/openssl.cnf openssl.cnf
修改openssl.cnf
[ req ]
distinguished_name = req_distinguished_name
req_extensions = v3_req #取消这行注释
# 确保req_distinguished_name下没有 0.xxx 的标签，有的话把0.xxx的0. 去掉
[ req_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = CN
stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = GuangDong
localityName = Locality Name (eg, city)
localityName_default = ShenZhen
organizationalUnitName = Organizational Unit Name (eg, section)
organizationalUnitName_default = 303 IT Lab
commonName = IT Lab
commonName_max = 64
[ v3_req ]
# Extensions to add to a certificate request
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names #增加这行
# 新增以下部分
[ alt_names ]
DNS.1 = abc.com
DNS.2 = *.abc.com
DNS.3 = xyz.com
DNS.4 = *.xyz.com
可以自行增加多域名
创建相关目录及文件
mkdir -p CA/{certs,crl,newcerts,private}
touch CA/index.txt
echo 00 > CA/serial
1.生成ca.key并自签署
openssl req -sha256 -new -x509 -days 3650 -keyout ca.key -out ca.crt -config openssl.cnf
2.生成server.key
openssl genrsa -out server.key 2048
3.生成证书签名请求
openssl req -new -sha256 -key server.key -out server.csr -config openssl.cnf
Common Name 就是在这一步填写 *.abc.com common name一定要在alt_names中包含
4.查看签名请求文件信息
openssl req -in server.csr -text
检查 Signature Algorithm 是不是sha256WithRSAEncryptio
5.使用自签署的CA，签署server.scr
openssl ca -in server.csr -md sha256 -out server.crt -cert ca.crt -keyfile ca.key -extensions v3_req -config openssl.cnf
注意：即便是你前面是sha256的根证书和sha256的请求文件，如果不加-md sha256，默认是按照sha1进行签名的
6.查看证书
openssl x509 -in server.crt -text
同样检查 Signature Algorithm 是不是sha256WithRSAEncryptio