How to access shared resources from two different domains
Accessing shared files from two different domains can be problematic most times. Especially when you have different forest. This is also the same with issues deploying an image from one WDS server in one domain to the other. Most times, it requires you to configure trust relationships, permissions etc. In this article, you will learn how to access shared files from two different domains/Forest. Please see Active Directory Forest – Trees and Domain and Sites, Active Directory: How to Setup a Domain Controller, and how to install and configure Active Directory Domain Services on Windows Server 2022.
Note: Since there is no one solution fits all. It is vital for you to have a proper understanding of your domains in order to determine the various options available for sharing files. You can also perform file sharing via the File Explore, computer Management, and through Map Network Drive etc.
Note: Microsoft Active Directory consists of Forests and Domains. A forest is a collection of one or more Active Directory domains that share a common logical structure, directory schema (class and attribute definitions), directory configuration (site and replication information), and global catalog (forest-wide search capabilities).
Note: Domains in the same forest are automatically linked with two-way, transitive trust relationships.
Also, see “The trust relationship between this workstation and the primary domain failed“, and how to fix “Specify user account name when adding a DC to an existing Forest“.
Possible Approaches
Most times, you are required to set up a Domain trust to achieve this depending on your Active Directory Design Model. Domain Trusts enable one domain to recognize the users and groups in another domain or (forest).
There are different types of trusts, including one-way and two-way trusts, depending on the level of access and authentication required.
But, when the two domains are in separate Active Directory forests. You will have to set up Forest Trusts to enable access. Forest Trusts establish a trust relationship between the entire forest, providing greater flexibility and trust between multiple domains within each forest.
You could explore Universal Groups. When granting access across different domains. Oftentimes, Universal Groups are utilized. Universal groups are not domain-specific, making them a more suitable choice for managing permissions across domains.
Other options are VPN or Direct Network Connection, and ensuring all the required network configurations are in place. But, I will not be using any of these approaches. Also, see how to fix “Error Code: 0x80070035: MDT unable to access the Log share, the Network Path was not found“, and how to “Enter connection information for your on-premise directory or forests: Azure AD connect unable to connect directory, forest not available“.
Access Shared Folders via Access Resources
Note: As mentioned earlier, domains in the same forest are automatically linked with two-way, transitive trust relationships. Therefore, you do not have to implement anything further to access resources in a different domain.
Users from one domain can access shared resources in another domain by providing credentials during authentication. This can be achieved by using the “username” prefix with the domain name.
For example (“TechDirect\Christian”). This method works great due to the proprietary local area network (LAN) protocols like NetBIOS and NetBEUI. This method supports domain trust where each domain is an island of its own.
We will be using the Run dialog box which is used to open any utility or folder directly. To do the same, follow the steps given below. Launch the Run box using Keyboard Shortcut Win + R.
Once the dialog box appears, type \\<domain name>\<Shared-Folder>. You need to replace <Domain-Name> and <Shared-Folder> with the actual name of of your domain and shared folder name respectively. It is also sufficient to type \\<domain name>\ only and browse to the shared folder.
Once you have entered the correct name, click OK or hit Enter.
If you do not have the right privilege, you will be required to enter your credentials.
Please, see Convert Windows Server Datacenter to Standard: Install via iDRAC Virtual Media, and How to delete a VM and Storage in Proxmox.
Authentication via User Principal Name (UPN) or sAMAccountName from another Forest
However, since I am accessing this shared folder from a different domain in a different forest. This will also work. But, I provide credentials from the actual domain I wish to access its shared resources.
Note: It’s important to note that you have to use the sAMAccountName format, the domain portion is a single label, akin to a NetBIOS name. This is because sAMAccountName has no “knowledge” of DNS or Internet standards.
domain\username or username@domain.With this approach, you do not need to enter the expand the “More choices” options
Optional steps only
If your authentication fails due to a wrong password or whatever. Then you can try again by using the more option. Technically, the options above and below should work if your credentials are correct.
With the right credentials, you should be able to access the shared resources from the other domain.
As you can see, I am now copying the files I need from the other domain to my second domain.
FAQs relating to Cross Domain Access, NetBIOS and DNS
What Security Considerations Should I Keep in Mind When Accessing Shared Files Across Domains?
Since security is very critical, when using trust relationships, ensure they are configured properly and secured. Limit access to only necessary resources. Consider using VPNs etc. Regularly audit and monitor file access to detect and prevent unauthorized activities.
Are There Other Methods for Cross-Domain File Access Without Trusts?
There are other options such as workgroup-based access. Here users authenticate using local accounts on the target server. However, this method can be less secure and more challenging to manage. Another option is to use technologies like VPNs or cloud-based file-sharing platforms for external access.
What’s the difference between NetBIOS and DNS?
The Domain Name System (DNS) is a directory for communication between devices over the internet. An internet connection is required to use DNS, but NetBIOS is available to all machines on a local area network.
I hope you found this blog post helpful on how to access shared files from two different domains. Please let me know in the comment section if you have any questions.
