Restrict access to website hosted on S3

Edit: User/group based restrictions do not work for static websites hosted in S3 since AWS is not registering your AWS Management Console (path: amazon.com) credentials/cookies for S3 (path: amazonaws.com) and not checking for them either.

Workaround: www.s3auth.com - Basic Auth for S3 buckets might do the trick for you but involves a third party. Another solution may be Query String Request Authentication, using an EC2 instance or the Elastic Beanstalk Java SE Static Files Option. We are currently exploring securing our buckets with an Amazon API Gateway as Amazon S3 Proxy.

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Sidenote: There are some additional things to look out for, which are often not directly pointed out.

It is currently not possible in bucket policies to grant or restrict group access, only specific users. Since you also generally don't want to update each bucket policy for each change in your user structure and bucket policies might (unintentionally) interfere with your user policies you may not want to use bucket policies.

The user/group based policies only work with the s3:GetBucketLocation and s3:ListAllMyBuckets attached to arn:aws:s3:::* or * (unfortunately no filtering possible here, all bucket names will be visible for users/groups with this policy).

IAM Policy Example: (not a S3 Bucket Policy and not working for Static Website Hosting)

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "s3:ListAllMyBuckets",
                "s3:GetBucketLocation"
            ],
            "Resource": [
                "arn:aws:s3:::*"
            ]
        },
        {
            "Effect": "Allow",
            "Action": "s3:GetObject",
            "Resource": [
                "arn:aws:s3:::YOURBUCKETNAME",
                "arn:aws:s3:::YOURBUCKETNAME/*"
            ]
        }
    ]
}

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More detailed blog post: "How to Restrict Amazon S3 Bucket Access to a Specific IAM Role"

Yes it indeed is possible. Better starting point for you would be read S3 access control.

But by default the buckets created on S3 aren't public. So the default behaviour should be that it will only be accessible to person/program who/which has knowledge of your access and secret key.

You may also edit bucket permission in order to give access to a particular AWS account or an email id.

In order to restrict access to certain IPs, you may create additional bucket policy.

Restricting Access to Specific IP Addresses

This statement grants permissions to any user to perform any S3 action on objects in the specified bucket. However, the request must originate from the range of IP addresses specified in the condition. The condition in this statement identifies 192.168.143.* range of allowed IP addresses with one exception, 192.168.143.188.

Note that the IPAddress and NotIpAddress values specified in the condition uses CIDR notation described in RFC 2632. For more information, go to http://www.rfc-editor.org/rfc/rfc4632.txt.

{
    "Version": "2012-10-17",
    "Id": "S3PolicyId1",
    "Statement": [
        {
            "Sid": "IPAllow",
            "Effect": "Allow",
            "Principal": "*",
            "Action": "s3:*",
            "Resource": "arn:aws:s3:::bucket/*",
            "Condition" : {
                "IpAddress" : {
                    "aws:SourceIp": "192.168.143.0/24" 
                },
                "NotIpAddress" : {
                    "aws:SourceIp": "192.168.143.188/32" 
                } 
            } 
        } 
    ]
}

For more, read here and here.