What is it called if the ACL automatically prevents access to anyone who is not on the list?
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Go to examples This page provides an overview of access control lists (ACLs). To learn about other ways of controlling access to buckets and objects, read Overview of Access Control. Should you use access control lists?In most cases, Identity and Access Management (IAM) is the recommended method for controlling access to your resources. It provides access control across all of Google Cloud, and it allows permissions granted to parent resources, such as projects, to be inherited by child resources, such as buckets and objects. See Using IAM Permissions for guides to working with IAM in Cloud Storage. IAM and ACLs work in tandem to grant access to your buckets and objects: a user only needs permission from either IAM or an ACL to access a bucket or object. You most likely want to use ACLs if you need to customize access to individual objects within a bucket, since IAM permissions apply to all objects within a bucket. However, you should still use IAM for any access that is common to all objects in a bucket, because this reduces the amount of micro-managing you have to do. What is an access control list?An access control list (ACL) is a mechanism you can use to define who has access to your buckets and objects, as well as what level of access they have. In Cloud Storage, you apply ACLs to individual buckets and objects. Each ACL consists of one or more entries. An entry gives a specific user (or group) the ability to perform specific actions. Each entry consists of two pieces of information:
As an example, suppose you have a bucket that you want anyone to be able to access objects from, but you also want your collaborator to be able to add or remove objects from the bucket. In this case, your ACL would consist of two entries:
The maximum number of ACL entries you can create for a bucket or object is 100. When the entry scope is a group or domain, it counts as one ACL entry regardless of how many users are in the group or domain. When a user requests access to a bucket or object, the Cloud Storage system reads the bucket or object ACL and determines whether to allow or reject the access request. If the ACL grants the user permission for the requested operation, the request is allowed. If the ACL does not grant the user permission for the requested operation, the request fails and a 403 Forbidden error is returned. Note that while ACLs can be used to manage most actions involving buckets and objects, the ability to create a bucket comes from having the appropriate project permission. PermissionsPermissions describe what can be done to a given object or bucket. Cloud Storage lets you assign the following concentric permissions for your buckets and objects, as shown in the following table:
1 The following bucket metadata properties cannot be changed: acl, cors, defaultObjectAcl, lifecycle, logging, versioning, and website. In this page, we generally refer to the permissions as READER, WRITER, and OWNER, which are how they are specified in the JSON API and the Google Cloud console. If you are using the XML API, the equivalent permissions are READ, WRITE, and FULL_CONTROL, respectively. And, when you use OAuth 2.0 authentication to authenticate tools and applications (grant permission to them) to access Google Cloud Storage API on your behalf, access is restricted by OAuth scope devstorage.read_only, devstorage.read_write, and devstorage.full_control. The following table summarizes the permissions terminology you commonly encounter:
ScopesScopes specify who it is that has a given permission. An ACL consists of one or more entries, where each entry grants permissions to a scope. You can specify an ACL scope using any of the following entities:
Concentric permissions and scopesWhen specifying ACLs in Cloud Storage, you do not need to list multiple scopes to grant multiple permissions. Cloud Storage uses concentric permissions, so when you grant WRITER permission, you also grant READER permission, and if you grant OWNER permission, you also grant READER and WRITER permission. When specifying an ACL using the Google Cloud console, JSON API, or gsutil, you can specify multiple scopes for the same entry. The most permissive permission is the access granted to the scope. For example, if you provide two entries for a user, one with READER permission and one with WRITER permission on a bucket, the user will have WRITER permission on the bucket. In the XML API, it is not possible to provide two ACL entries with the same scope. For example, granting a user READ permission and WRITE permission on a bucket results in an error. Instead, grant the user WRITE permission, which also grants the user READ permission. Predefined ACLsA predefined or "canned" ACL is an alias for a set of specific ACL entries that you can use to quickly apply many ACL entries at once to a bucket or object. The table below lists predefined ACLs and shows which ACL entries are applied for each predefined ACL. When using the table below, note that:
* By default, publicly readable objects are served with a Cache-Control header that allows the objects to be cached for 3600 seconds. If you need to ensure that updates become visible immediately, you should set the Cache-Control metadata for the objects to Cache-Control:private, max-age=0, no-transform. Default ACLsWhen buckets are created or objects are uploaded, if you do not explicitly assign an ACL to them, they are given the default ACL. You can change the default ACL given to an object; the process to do so is described in Changing default object ACLs. Note that when you change the default ACL, the ACLs of objects that already exist in the bucket or buckets that already exist in the project remain unchanged. Default bucket ACLsAll buckets are owned by the project owners group. Additionally, project owners are granted OWNER permission for any buckets inside their project that use a predefined ACL. If you create a bucket with the default bucket ACL—that is, you do not specify a predefined ACL when you create the bucket—your bucket has the predefined projectPrivate ACL applied to it. Default object ACLsBy default, anyone who has OWNER permission or WRITER permission on a bucket can upload objects into that bucket. When you upload an object, you can provide a predefined ACL or not specify an ACL at all. If you don't specify an ACL, Cloud Storage applies the bucket's default object ACL to the object. Every bucket has a default object ACL, and this ACL is applied to all objects uploaded to that bucket without a predefined ACL or an ACL specified in the request (JSON API only). The initial value for the default object ACL of every bucket is projectPrivate. Based on how objects are uploaded, object ACLs are applied accordingly:
ACL behaviorCloud Storage helps you adhere to best practices by enforcing some ACL modification rules, which prevent you from setting ACLs that make data inaccessible:
You cannot apply ACLs that change the ownership of a bucket or object (which should not be confused with the OWNER permission). Once created in Cloud Storage, bucket and object ownership are permanent. You can, however, effectively change the ownership of objects (but not buckets) by replacing them. Replacement is basically a delete operation followed immediately by an upload operation. During an upload operation, the person who is performing the upload becomes the owner of the object. Keep in mind that to replace an object, the person performing the replacement (and gaining ownership of the object by doing so) must have WRITER or OWNER permission on the bucket in which the object is being uploaded. What's next
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates. Last updated 2022-08-18 UTC. [{ "type": "thumb-down", "id": "hardToUnderstand", "label":"Hard to understand" },{ "type": "thumb-down", "id": "incorrectInformationOrSampleCode", "label":"Incorrect information or sample code" },{ "type": "thumb-down", "id": "missingTheInformationSamplesINeed", "label":"Missing the information/samples I need" },{ "type": "thumb-down", "id": "otherDown", "label":"Other" }] [{ "type": "thumb-up", "id": "easyToUnderstand", "label":"Easy to understand" },{ "type": "thumb-up", "id": "solvedMyProblem", "label":"Solved my problem" },{ "type": "thumb-up", "id": "otherUp", "label":"Other" }] Which of the following uses access control lists ACLs to filter packets as a form of security?A screening router is the router that is most external to your network and closest to the internet. It uses access control lists (ACLs) to filter packets as a form of security.
Which of the following is an example of rule based access control?Which of the following is an example of rule-based access control? Router access control lists that allow or deny traffic based on the characteristics of an IP packet. A router access control list that allows or denies traffic based on the characteristics of an IP packet is an example of rule-based access control.
Which of the following is undetectable software that allows administrator level access?SYS-201. Which of the following is the best example of the principle of least privilege?Which of the following practices are the BEST example of the principle of least privilege? All users on a Windows workstation are limited user except for one user, who is responsible for maintaining the system.
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