自行签发ca证书

> openssl genrsa -des3 -out server.enc.key 2048   
> password
> openssl rsa -in server.enc.key -out server.key    # 写入密码

> openssl req -new -sha256  
    -x509 
    -days 36500 
    -key server.key 
    -subj "/C=CN/ST=Hubei/L=Wuhan/O=ChreemTech/OU=FS/CN=chreem.club" 
    -extensions SAN 
    -config <(cat ./conf.cnf) 
    -out server.crt