Mastery of Active Directory groups can streamline management and pave the way for automation

At first glance, Active Directory groups are a simple and straightforward way to manage identities (users and/or computers) and assign permissions. Users or computers are added as members of the group, and the group is referenced in access control lists (ACLs) on file shares, mailboxes, applications, or other resources. company. But experienced administrators know that this simplicity quickly disappears as environments evolve. As group memberships grow, membership management becomes increasingly complex.

Over the years, Microsoft and others have developed best practices for managing groups and permissions in an Active Directory environment. These strategies are somewhat of a lost art, but there is value to be gained by leveraging these layers of sophistication.

Active Directory technical upgrade

Before delving into the technical nuances with Active Directory, let’s briefly recap some terminology and structural components.

Active Directory is built as a hierarchy of domains, the entirety of which is known as a forest. Domains primarily define the scope of replication, which is one of the primary reasons why multi-domain forests exist. Active Directory is made up of several types of objects: users, computers, groups, organizational units (OU), etc. These objects and all of their attributes are replicated between domain controllers within that domain. As more objects are added to a domain, the network traffic required for replication increases, which can potentially become a problem if your domain spans multiple physical locations.

Forests allow you to subdivide Active Directory into domains to optimize both security and the scope of object replication. Objects are replicated to a subset of domain controllers (those configured as global catalog servers) in other domains in the forest, but only with a subset of object attributes. Global catalog servers allow you to adjust the balance between the need for replication and the need to trace across domain boundaries to resolve object attributes.

In cases where two domains from different forests need to share resources, domain trusts can be used to authenticate users and provide permissions to users in the foreign domain. Trusts are typically used for the purposes of a business partnership or as the first step in a merger.

Understand group scope

Active Directory groups can be created for messaging or security purposes, and they require a name and group members (users, computers, or other groups). In addition to these options, groups can have one of three scopes: global, universal, and domain local. These scopes define the visibility of the group in the Active Directory forest and impact which objects can be members of the group.

Global groups have the broadest visibility of all group scopes as they are the only type of group that can be a member of domain local groups in trusted external domains, and they can also be listed as members of groups universal or domain premises in other domains in the same forest. Although global groups can be referenced as members in other domains, they can only contain certain types of objects from their own domain (users, computers, and other global groups). This is a key distinction because of its impact on replication. Changes to global group membership should only be replicated within the domain, not to global catalog servers in the forest.

Universal groups can be members of universal and domain local groups in domains in the forest, and they can have users, computers, or global and universal groups as members. Membership of universal groups can potentially be cached in the global catalog, which would incur a replication cost each time group membership changes.

Domain local groups are the only type of group that can include members of trusted external domains (users, computers, and global groups). Domain local group membership can include users, computers, and global or universal groups from any domain in the forest, as well as other domain local groups from the same domain.

Optimization goals and strategies

There are two main reasons why it’s in your best interest to take advantage of best practices with Active Directory groups.

First, you can lighten your administrative workload by implementing role-based access control (RBAC). Basically, the goal of RBAC is to minimize the number of changes required when adding a user or changing a user’s role. With RBAC, you should be able to add a new user to one or two groups to grant them permissions to all the resources they need within your organization.

Second, you can minimize the technical overhead required to assign user permissions through group membership changes. Part of this involves Active Directory replication. This also includes things like file and sharing permissions, access to web or on-premises applications, and any other enterprise resource group memberships that may have an impact.

Both of these goals can be achieved almost exclusively through group nesting, which, to put it simply, is a strategic, multi-level approach to group membership. Group nesting is the process of making a group a member of one or more other groups, allowing administrators to add a user or computer to a single group while gaining access to resources offered by multiple groups. groups.

To minimize the replication overhead involved with changes in group memberships, nesting of groups should be limited to a specific order. In single-domain forests, accounts (users or computers) must be placed in global groups that correspond to a worker role. These global groups should then be placed into domain local groups, which are used to provide some level of access to resources such as applications or file stores. The acronym used to memorize this sequence is AGDLP (account, global, domain local, permission).

Multi-domain forests are a bit more complex due to group membership restrictions and the need to minimize replication. In a multidomain environment, the best practice is to place global groups as members of universal groups, and universal groups as members of domain local groups. The acronym AGUDLP (account, global, universal, domain local, permission) applies to multi-domains. Using this structure minimizes changes to global group membership (minimizing replication), as most changes will be limited to global groups.

Apply best practices

The first step in implementing these best practices is to develop a plan, which requires an understanding of your business needs. It starts with understanding how your business groups divide, what resources your users need access to, and how the two intersect.

Global groups for sales roles can be as simple as one per sales group (Sales, Engineering, HR, IT, Executives) or subdivided as needed (Sales Team, Leads, Sales Management). The level at which you break down the roles depends entirely on the resources and level of access needed by those users to do their job. Fortunately, these groups are easy to expand as business needs change. So while it’s certainly worth planning for your needs and building in some flexibility for growth, you don’t need to overthink it.

Domain local groups used to manage equation permissions and access are a bit simpler. Typically for things like files and folders there are only a few potential permission levels, and in most cases this can be broken down into things like read-only, read-and-write and full control. Creating a new file store will require a new set of domain local groups, but once this framework is created you will only need to add a few roles as group members rather than users individual. Applications and other types of resources that leverage Active Directory groups can potentially add complexity, but it really depends on the application.

The glue that holds it all together is adding your global groups – which manage the role aspect of your policy – as members of the domain local groups needed for that role to be granted the correct permissions for those users. For example: business users might need to be able to view documents owned by the engineering team, so business users would be placed in a global group, which would be a member of a domain local group that provides online access. read-only to engineering files. The same sales user group can be a member of a domain local group that provides read-write permissions to sales files, as well as any other permission group appropriate for their business role. New users would be placed in the appropriate group for their role and automatically granted permission to access any number of resources required for their role.

Universal groups only come into play in Active Directory forests with multiple domains where users in one domain need access to resources in another domain. Where global groups define business roles and domain local groups map permissions, universal groups can be viewed as a second layer of the business role to enhance cross-domain functionality. This strategy becomes particularly useful for performance reasons if universal group membership caching is enabled in your global catalog servers.

A final recommendation that will save your sanity is to establish a standard naming convention for each of your group types. Something like Gl-SalesTeam (group scope and function) or SalesTeam-Role (group function and type) helps identify both the purpose of the group and the sales group it supports. Permission groups may require a little more detail to be fully descriptive, as there is a wide range of resources they could correspond to. For example, ACL-Files-Engineering-RW (ACL providing read-write access to the engineering file share) or ACL-LocalAdmin-Server1 (for local administrator privileges on server1) . Naming conventions will help streamline all aspects of the maintenance process, including finding and reviewing user access, and possibly automation.

Copyright © 2022 IDG Communications, Inc.

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