gistfile1.txt

{
  "Id": "SourceIP",
  "Statement": [
    {
      "Action": "s3:*",
      "Condition": {
        "NotIpAddress": {
          "aws:SourceIp": [
            "10.0.0.0/8",
            "172.16.0.0/12",
            "192.168.0.0/24"
          ]
        }
      },
      "Effect": "Deny",
      "Principal": "*",
      "Resource": [
        "arn:aws:s3:::YOURBUCKETNAMEHERE",
        "arn:aws:s3:::YOURBUCKETNAMEHERE/*"
      ],
      "Sid": "SourceIP"
    }
  ],
  "Version": "2012-10-17"
}