This section presents a few examples of typical use cases for bucket policies. The policies use Show
A bucket policy is a resource-based policy that you can use to grant access permissions to your bucket and the objects in it. Only the bucket owner can associate a policy with a bucket. The permissions attached to the bucket apply to all of the objects in the bucket that are owned by the bucket owner. These permissions do not apply to objects owned by other Amazon Web Services accounts. By default, when another Amazon Web Services account uploads an object to your S3 bucket, that account (the object writer) owns the object, has access to it, and can grant other users access to it through access control lists (ACLs). You can use Object Ownership to change this default behavior so that ACLs are disabled and you, as the bucket owner, automatically own every object in your bucket. As a result, access control for your data is based on policies, such as IAM policies, S3 bucket policies, virtual private cloud (VPC) endpoint policies, and Amazon Organizations service control policies (SCPs). For more information, see Controlling ownership of objects and disabling ACLs for your bucket. For more information about bucket policies, see Using bucket policies. Bucket policies are limited to 20 KB in size. You can use the Amazon Policy Generator to create a bucket policy for your Amazon S3 bucket. You can then use the generated document to set your bucket policy by using the Amazon S3 console, through several third-party tools, or through your application. When testing permissions by using the Amazon S3 console, you must grant additional permissions that the console requires— Topics
Granting permissions to multiple accounts with added conditionsThe following example policy grants the Use caution when granting anonymous access to your Amazon S3 bucket or disabling block public access settings. When you grant anonymous access, anyone in the world can access your bucket. We recommend that you never grant anonymous access to your Amazon S3 bucket unless you specifically need to, such as with static website hosting.
Granting read-only permission to an anonymous userThe following example policy grants the Use caution when granting anonymous access to your Amazon S3 bucket or disabling block public access settings. When you grant anonymous access, anyone in the world can access your bucket. We recommend that you never grant anonymous access to your Amazon S3 bucket unless you specifically need to, such as with static website hosting.
Limiting access to specific IP addressesThe following example denies permissions to any user to perform any Amazon S3 operations on objects in the specified S3 bucket unless the request originates from the range of IP addresses that are specified in the condition. This statement identifies The Before using this policy, replace the
Allowing IPv4 and IPv6 addressesWhen you start using IPv6 addresses, we recommend that you update all of your organization's policies with your IPv6 address ranges in addition to your existing IPv4 ranges to ensure that the policies continue to work as you make the transition to IPv6. The following example bucket policy shows how to mix IPv4 and IPv6 address ranges to cover all of your organization's valid IP addresses. The example policy
allows access to the example IP addresses The IPv6 values for Replace the IP address ranges in this example with appropriate values for your use case before using this policy. Otherwise, you might lose the ability to access your bucket.
Restricting access to a specific HTTP refererSuppose that you have a website with a domain name (
Make sure that the browsers that you use include the HTTP We recommend that you use caution when using the The Granting permission to an Amazon CloudFront OAIThe following example bucket policy grants a CloudFront origin access identity (OAI) permission to get (read) all objects in your Amazon S3 bucket. You can use a CloudFront OAI to allow users to access objects in your bucket through CloudFront but not directly through Amazon S3. For more information, see Restricting Access to Amazon S3 Content by Using an Origin Access Identity in the Amazon CloudFront Developer Guide. The following policy uses the OAI’s ID as the policy’s To use this example:
Adding a bucket policy to require MFAAmazon S3 supports MFA-protected API access, a feature that can enforce multi-factor authentication (MFA) for access to your Amazon S3 resources. Multi-factor authentication provides an extra level of security that you can apply to your Amazon environment. MFA is a security feature that requires users to prove physical possession of an MFA device by providing a valid MFA code. For more information, see Amazon Multi-Factor Authentication. You can require MFA for any requests to access your Amazon S3 resources. To enforce the MFA requirement, use the When Amazon S3 receives a request with multi-factor authentication, the
The The following bucket policy is an extension of the preceding bucket policy. It includes two policy statements. One statement allows the
You can optionally use a numeric condition to limit the duration for which the
Granting cross-account permissions to upload objects while ensuring the bucket owner has full controlThe following example shows how to allow another Amazon Web Services account to upload objects to your bucket while ensuring that you have full control of the uploaded objects. This policy grants a specific Amazon Web Services account (
Granting permissions for Amazon S3 Inventory and Amazon S3 analyticsAmazon S3 Inventory creates lists of the objects in an Amazon S3 bucket, and Amazon S3 analytics export creates output files of the data used in the analysis. The bucket that the inventory lists the objects for is called the source bucket. The bucket where the inventory file or the analytics export file is written to is called a destination bucket. When setting up an inventory or an analytics export, you must create a bucket policy for the destination bucket. For more information, see Amazon S3 Inventory and Amazon S3 analytics – Storage Class Analysis. The following example bucket policy grants Amazon S3 permission to write objects (
Restricting access to an Amazon S3 Inventory reportAmazon S3 Inventory creates lists of the objects in an S3 bucket and the metadata for each object. The To restrict a user from configuring an S3 Inventory report of all object metadata available, remove the To restrict a user from accessing your S3 Inventory report in a destination bucket, create a bucket policy like the following example on the destination bucket. This example bucket policy denies all the principals except the user
Granting permissions for Amazon S3 Storage LensS3 Storage Lens aggregates your metrics and displays the information in the Account snapshot section on the Amazon S3 console Buckets page. S3 Storage Lens also provides an interactive dashboard that you can use to visualize insights and trends, flag outliers, and receive recommendations for optimizing storage costs and applying data-protection best practices. Your dashboard has drill-down options to generate insights at the organization, account, bucket, object, or prefix level. You can also send a once-daily metrics export in CSV or Parquet format to an S3 bucket. S3 Storage Lens can aggregate your storage usage to metrics exports in an Amazon S3 bucket for further analysis. The bucket where S3 Storage Lens places its metrics exports is known as the destination bucket. When setting up your S3 Storage Lens metrics export, you must have a bucket policy for the destination bucket. For more information, see Assessing your storage activity and usage with Amazon S3 Storage Lens. The following example bucket policy grants Amazon S3 permission to write objects (
When setting up an S3
Storage Lens organization-level metrics export, use the following modification to the previous bucket policy's
Which of the below feature can restrict access to S3?The Amazon S3 Block Public Access feature provides settings for access points, buckets, and accounts to help you manage public access to Amazon S3 resources. By default, new buckets, access points, and objects don't allow public access.
Which Amazon S3 bucket policy can limit access to a specific object?You can use the NotPrincipal element of an IAM or S3 bucket policy to limit resource access to a specific set of users.
What methods can be used to grant access to an object in S3?Grant public read access in one of these ways: Update the object's access control list (ACL) using the Amazon S3 console. Update the object's ACL using the AWS Command Line Interface (AWS CLI) Use a bucket policy that grants public read access to a specific object tag.
Which methods of access control can you implement using S3 bucket policies?ACLs were the first authorization mechanism in S3. Bucket policies are the newer method, and the method used for almost all AWS services. Policies can implement very complex rules and permissions, ACLs are simplistic (they have ALLOW but no DENY). To manage S3 you need a solid understanding of both.
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