AWSTemplateFormatVersion: "2010-09-09"
Resources:
  SecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: "wide open group"
  SecurityGroupIngress:
    Type: AWS::EC2::SecurityGroupIngress
    Properties:
      GroupId: !GetAtt SecurityGroup.GroupId
      IpProtocol: -1
      CidrIp: 10.0.0.0/16