Oct 072019
 
Microsoft Windows Server Logo Image

Today I’m going to be talking about Read Only Domain Controllers (RODC). An RODC is a Read Only Domain Controller for Active Directory Services inside of Microsoft Windows Server. It has become one of my favorite discoveries in the last 10 years for use with clients in certain situations.

A Read Only Domain Controller is similar to a regular Domain Controller, with the exception that the content is synchronized and available as a read-only copy. You cannot write to an RODC AD database.

Let’s explore RODC’s in more depth and find out what they are, why they are used, and use-case scenario examples.

What is an RODC

Read Only Domain Controllers were originally released with Windows Server 2008, and have been available on all versions since (including Windows Server 2008R2, Windows Server 2012/2012R2, Windows Server 2016, and Windows Server 2019).

A Domain controller that is an RODC contains a read-only cached copy of the Active Directory database. Additional sets of controls are available to control and limit this information and what is stored and cached.

Why an RODC

A Read Only Domain Controller is typically placed in situations and scenarios where a standard writable domain controller cannot be placed. The AD data/information can be filtered so that important items such as passwords, credentials, and other security sensitive information are not cached on that server. This provides a safety mechanism if the RODC is stolen or compromised (either physically, or virtually). You can control it so that only required information is cached, such as credentials for the users in the specific office.

RODC’s are meant to be used at remote offices and/or branch offices (ROBO) to allow services to function that rely on Active Directory such as file/print services and other Active Directory applications. Also, typically at these sites it either wouldn’t make sense or be safe to have a writable domain controller, however the RODC is needed to cache AD information, and enhance performance of these AD applications.

Offloading Active Directory requests to a single cached copy onsite on an RODC significantly reduces bandwidth pipe requirements versus having numerous computers and users authenticating and requesting Active Directory content over a site-to-site VPN between the main office and remote office/branch office.

Also, if you have an office with an unstable internet connection where the site-to-site VPN regularly has issues or isn’t always available, having an RODC available to handle Active Directory requests can keep that office online and functioning.

Scenarios for an RODC

In the past I’ve used Read Only Domain Controllers for a few different types of scenarios. I’ll get in to them below and explain why.

The scenarios:

  • AD Cache for ROBO (Remote Office Branch Office)
    • Unstable internet connection
    • AD Services at remote site (File/Print, LoB)
    • Numerous Users accessing Active Directory
    • Improve login times
  • ROBO with Potential Security issues (theft, lack of survailence, etc.)
    • Office is in remote area with delayed physical security response, risk of theft
    • Server physical security at risk, employees could have access
  • Corporate Infrastructure hosted in the Cloud
    • Domain Controller in the Cloud
    • Need a DC on-premise to handle logins and resource access

AD Cache for ROBO (Remote Office Branch Office)

Implementing an RODC in this situation is an excellent example. In a situation where an office has unreliable (intermittent or slow) internet but is critical to business continuity, an RODC can keep them up and running uninterrupted.

Typically, if you were just using a Site-to-Site VPN, if that connection went down, users wouldn’t be able to authenticate against Active Directory or access resources in Active Directory. Having an RODC on-site, allows them to authenticate (if their credentials are stored) and access resources.

As most IT professionals are aware, having a large number of users authenticating and accessing these resources over a VPN can use up the bandwidth pipe and cause issues. Having an RODC locally virtually eliminates VPN bandwidth usage to only Active Directory synchronization, and synchronization deltas.

Finally, having users authenticate locally instead of a saturated high latency VPN connection, improves their login time and performance.

ROBO with Potential Security issues (theft, lack of survailence, etc.)

If you have a remote site with security concerns, an RODC can help you with your security strategy.

If an RODC is physically stolen, only credentials that are filtered to be cached on that RODC are stored locally, this usually excludes administrative accounts as well as other users and services that aren’t accessed or used at the remote site. Also, because the domain controller isn’t writable, the thief cannot power on, inject data in to Active Directory and have it sync to your other domain controllers if they somehow gained access to your internal network.

The above also holds true for possible malicious employees who may have skills or knowledge, or allow other 3rd parties to have physical or virtual access to the server.

In the event of a disaster, restoring or recreating an RODC is easy and fast. Since it synchronizes from writable DCs on the network, the concerns of traditional writable domain controller restores don’t need to be considered.

Corporate Infrastructure hosted in the Cloud

If by chance most of your corporate infrastructure is hosted in the cloud, you know that you still need some on-premise resources and infrastructure to handle and offload bandwidth requirements between your LAN network and virtual cloud LAN network.

Typically, in most cases you’d have an on-site on-premise domain controller to handle local login and authentication, as well as resource access. But why use a fully writable domain controller, when you can use an easy to manage and maintain RODC?

Using an RODC at your local site allows you to offload services off the pipe, to the RODC, again limiting bandwidth requirements to AD synchronizations and delta synchronizations. This allows your bandwidth to be used for more important things like Line of Business applications, e-mail, etc.

As most IT professionals prefer simple and functional, this keeps simplified and easy to manage.

Conclusion

RODC’s are a perfect tool to compliment your IT infrastructure and help secure it as well. I’ve placed numerous Read Only Domain Controllers at customers branch offices, remote oil and gas sites, and in various other scenarios.

Not only have they kept these customers up and running during outages, but the ease of use and ease of management make it common sense to use this technology.

May 162019
 

There may be a situation where you wish to completely reinstall WSUS from scratch. This can occur for a number of reasons, but most commonly is due to database corruption, or performance issues due to a WSUS database that hasn’t been maintained properly with the normal maintenance.

Commonly, when regular maintenance hasn’t occurred on a WSUS database, when an admin finally performs it, it can take days and weeks to re-index the database, clean up the database, and run the cleanup wizards.

Also, due to timeouts on IIS, the cleanup wizard may fail which could ultimately cause database corruption.

Administrators often want or choose to blast away their WSUS install, and completely start from scratch. I’ve done this numerous times in my own environment as well as numerous customer environments.

In this guide, we are going to assume that you’re running WSUS on a Windows Server that is dedicated to WSUS and is using the WID (Windows Internal Database) which is essentially a built-in version of SQL Express.

PLEASE NOTE: If you are using Microsoft SQL, these instructions will not apply to you and will require modification. Only use these instructions if the above applies to you.

What’s involved

WSUS (Windows Server Update Services) relies on numerous Windows roles and features to function. As part of the instructions we’ll need to completely clear out:

  • WSUS Role, Configuration, and Folders/Files
  • IIS Role, Configuration, and Folders/Files
  • WID Feature, Configuration, and Database Files

Since we are completely removing IIS (Role, Configuration, and Folders/Files), only proceed if the server is dedicated to WSUS. If you are using IIS for anything else, this will completely clear the configuration and files.

Let’s get to it!

Instructions

  1. Open “Server Manager” either on the host, or remotely and connect to the host you’d like to reinstall on.
  2. Open “Remove Roles and Features” wizard.
  3. Click “Next”, and select the Server, and click “Next” again.
  4. On the “Remove server roles” screen, under “Roles”, we want to de-select the following: “Web Server (IIS)” and “Windows Server Update Services” as shown below. Selecting WSUS and IIS Roles to be Removed
  5. Click “Next”
  6. On the “Remove features” screen, under “Features”, we want to de-select the following: “Windows Internal Database” and “Windows Process Activation Service” as shown below. Selecting WID and WPAS Features for Removal
  7. Click “Next” and follow the wizard to completion and remove the roles and features.
  8. Restart the Server.
  9. Open an administrative command prompt on the server, and run the command “powershell” or open powershell directly.
  10. Run the following command in powershell to remove any bits and pieces:
    Remove-WindowsFeature -Name UpdateServices,UpdateServices-DB,UpdateServices-RSAT,UpdateServices-API
  11. Restart the Server.
  12. We now must delete the WSUS folders and files. Delete the following folders:
    C:\WSUS
    C:\Program Files\Update Services

    Note: You may have stored the WSUS content directory somewhere else, please delete this as well.
  13. We now must delete the IIS folders and files (and configuration, including the WsusPool application pool, bindings, etc.). Delete the following folders:
    C:\inetpub
    C:\Windows\System32\inetsrv

    Note: You may have issues deleting the “inetsrv” directory. If this occurs, simply rename it to “inetsrv.bad”.
  14. We now must delete the WID (Windows Internal Database) folders and files (including the WSUS SQL Express database). Delete the following folder:
    C:\Windows\WID
  15. While we removed the IIS folders and files, we deleted a needed system file. Run the following command to restore the file:
    sfc /scannow
  16. Restart the Server.

WSUS, IIS, and WID have at this point been completely removed. We will now proceed to install, apply a memory fix, and configure WSUS.

For instructions on installing WSUS on Server Core, please click here: https://www.stephenwagner.com/2019/05/15/guide-using-installing-wsus-windows-server-core-2019/

  1. Open “powershell” (by typing powershell) and Install the WSUS Role with the following command:
    Install-WindowsFeature UpdateServices -Restart
  2. Run the post installation task command to configure WSUS:
    "C:\Program Files\Update Services\Tools\wsusutil.exe" postinstall CONTENT_DIR=C:\WSUS
  3. AT THIS POINT DO NOT CONTINUE CONFIGURING WSUS AS YOU MUST APPLY A MEMORY FIX TO IIS.
  4. Apply the “Private Memory Limit (KB)” fix as provided here: https://www.stephenwagner.com/2019/05/14/wsus-iis-memory-issue-error-connection-error/
  5. Restart the Server.
  6. Open the WSUS MMC on the server or remotely from a workstation on the network and connect it to the WSUS instance on your Server Core install.
  7. Run through the wizard as you would normally and perform an synchronization.
  8. WSUS has been re-installed.

And that’s it. You’ve completely reinstalled WSUS from scratch on your Windows Server.

May 152019
 

Windows Server Core (on Windows Server 2019) is a great way to reduce the performance and security footprint of your servers. The operating system itself is minimalist and provides no GUI accept for a command prompt, and some basic windows and tools.

All administration on Server Core must be performed via the command prompt, powershell, or remote administration tools (such as Server Manager, or the new Windows Admin Center.

Server Core provides a fantastic foundation for Windows Server Roles (roles that are integrated in the operating system), and can be installed with ease, managed remotely, and managed easily. It’s also nice too because you can allocate less CPU and RAM to virtual machines running Windows Server Core.

Getting started may be a bit tricky as you might need to learn and verse yourself with some commands, powershell, and remote management kung-fu, but overtime it’s easy!

Why WSUS?

I think I can speak for most admins out there when I say that a WSUS deployment typically consists of a single VM, with the WSUS, IIS, and WID roles installed.

WSUS is usually CPU and RAM intensive (when doing synchronizations), requires disk space, and doesn’t do much else. Because of the spikes, we usually keep this VM separate and don’t mix it with other LoBs or roles, with the exception of perhaps a file server.

Whether or not your VM runs WSUS alone, or also as a file server, since both of these roles are “Windows Roles and Features”, they are perfect to deploy on a Windows Server Core install.

There should be little administrative requirement on the WSUS server, other than re-indexing scripts, and cleanup scripts which can easily be ran from the command prompt, and the occasional Windows Update that will be installed.

Because you don’t require any 3rd party software, management consoles, or GUI related elements, it’s perfect for Server Core. By skipping on the GUI and applications, you’ll be able to allocate that memory, for WSUS/IIS itself.

How to Install and Configure WSUS on Windows Server Core

  1. Install Windows Server 2019 – Server Core
  2. Configure Network, Join to Domain, Update, etc.
  3. Open “powershell” (by typing powershell) and Install the WSUS Role with the following command:
    Install-WindowsFeature UpdateServices -Restart
  4. Run the post installation task command to configure WSUS:
    "C:\Program Files\Update Services\Tools\wsusutil.exe" postinstall CONTENT_DIR=C:\WSUS
  5. AT THIS POINT DO NOT CONTINUE CONFIGURING WSUS AS YOU MUST APPLY A MEMORY FIX TO IIS.
  6. Enable Remote IIS Management to manage and modify IIS config (to apply the memory fix below), as provided here: https://www.stephenwagner.com/2019/05/14/manage-remotely-iis-on-windows-server-2019-server-core/
  7. Apply “Private Memory Limit (KB)” fix as provided here: https://www.stephenwagner.com/2019/05/14/wsus-iis-memory-issue-error-connection-error/
  8. Install the “Windows Server Update Services” mmc applet which is included in the Windows 10 RSAT tools. Instructions to install the RSAT are provided here: https://www.stephenwagner.com/2018/10/05/windows-10-1809-october-update-rsat/
  9. Open the WSUS MMC on a server or workstation on the network and connect it to the WSUS instance on your Server Core install.
  10. Run through the wizard as you would normally and perform an synchronization.
  11. Modify your GPO to point your servers and workstations towards your WSUS server.
  12. Enable Windows Update “Features on Demand” and “Turn Windows features on or off” via GPO as provided here:
    https://www.stephenwagner.com/2018/10/08/enable-windows-update-features-on-demand-and-turn-windows-features-on-or-off-in-wsus-environments/
  13. Install the “sqlcmd” command so you can regularly run the WSUS re-index script, as provided here: https://www.stephenwagner.com/2019/05/14/run-wsus-cleanup-index-script-windows-server-core-without-sql-management-studio/

You’re done!

Don’t forget to regularly re-index your WSUS database and perform the routine maintenance!

Tips n Tricks

  • Need to view, modify, cut/paste, or delete files and folders? Open up notepad from the command prompt to get a simple GUI where you can do this.
  • CTRL + SHIFT + ESC will open a Task Manager to monitor the Server Core install
  • You can use “Server Manager” remotely to manage the Server Core install after you’ve enabled it inside of “sconfig”.
May 142019
 

You’re running WSUS (Windows Server Update Services) on Windows Server 2019 Server Core, and you want to run the WSUS Re-Index or WSUS Cleanup script, but you can’t because you cannot install the SQL Management Studio on Windows Server Core.

Well, there’s a way around this. To run SQL scripts on the WID (Windows Internal Database) on Windows Server Core, we’ll need to install “sqlcmd” (info here).

Now normally with Microsoft SQL, you’d simply connect remotely using the SQL Management Studio, and you can if you’re using fully blown Microsoft SQL Server with your WSUS implementation, however most of us aren’t. In most small deployments, WSUS is configured using WID (Windows Internal Database) which is essentially Microsoft SQL Express.

Microsoft SQL Express doesn’t support remote named pipe connections, and there’s no easy way to configure TCP connections with the registry editor, so the easiest way to accomplish executing SQL scripts is to install and use the “sqlcmd”.

Instructions

Install the SQLCMD command utility

  1. First we need to identify the version of SQL express that’s running WID on the server running Windows Server Core 2019.
  2. Open “notepad” and open the following file which containts the WID log.
    C:\Windows\WID\Log\error
  3. At the beginning of the log file, you’ll note the Microsoft SQL version that’s running. In my case it’s “Microsoft SQL Server 2014 (SP2-GDR)” specifically 12.0.5214.6 as shown below.
    2019-05-14 10:52:47.79 Server      Microsoft SQL Server 2014 (SP2-GDR) (KB4057120) - 12.0.5214.6 (X64) 
    	Jan  9 2018 15:03:12 
    	Copyright (c) Microsoft Corporation
    	Windows Internal Database (64-bit) on Windows NT 6.3  (Build 17763: ) (Hypervisor)
  4. The “sqlcmd” is part of the Microsoft SQL Server Feature Pack, so a quick search of “SQL Server 2014 SP2 Feature Pack” returned the following URL:
    https://www.microsoft.com/en-us/download/details.aspx?id=53164
  5. When you click download, you’ll notice multiple files. Choose the ”
    ENU\x64\MsSqlCmdLnUtils.msi” file to download.
  6. Copy this file over to your server running Windows Server Core.
  7. Execute and run the installer. Follow the prompts.
  8. You’ll notice the installer will error and require “Microsoft ODBC Driver 11 for SQL Server”. A quick search finds this download:
    https://www.microsoft.com/en-ca/download/details.aspx?id=36434
  9. Download the above file, install the “Microsoft ODBC Driver 11 for SQL Server”.
  10. Re-start the “MsSqlCmdLnUtils.msi” installer, and it should now complete.
  11. You have now installed the SQLcmd utility.

Run the WSUS Re-Index Script

  1. Download the WSUS Database Re-Index script from:
    https://gallery.technet.microsoft.com/scriptcenter/6f8cde49-5c52-4abd-9820-f1d270ddea61
  2. Copy the script to the server.
  3. Run the following command from the command prompt:
    sqlcmd -S np:\\.\pipe\Microsoft##WID\tsql\query –i C:\Folder\WsusDBMaintenance.sql

You’ve officially installed the sqlcmd and ran the WSUS Re-Index script on Windows Server Core. Congratulations!