Linux AD computer object operating system values

Introduction

So, why am I dealing with Linux AD computer object operating system values? OK, here is some background. In geographic services, engineering, etc. people often run GIS and CAD software from various big-name vendors on Windows Servers. But it also has a rich and varied open source ecosystem driven by academic efforts. Often a lot of these handy tools only run in Linux. The Windows Linux Subsystem might be an option for client-based or interactive tools. But when running a service I tend to use Ubuntu. It is the most approachable for me and, you can buy support for in an enterprise setting is do desired or required.

To keep things as easy as possible and try to safeguard the concept of single sign-on we join these Ubuntu servers to Active Directory (AD) so they can log with their AD credentials.

Pre-staging computer objects

When joining an Ubuntu server to AD it partially fills out the Operating System values.

Not too detailed and only partially filled out.

However, we tend to pre-stage the computer accounts in the correct OU and not create them automatically in the default Computer OU when joining. In that case, the Operating System values seem to be left all blank. We can fix that with PowerShell.

Don’t worry, the screenshot is from my lab with my fictitious Active Directory forest/domain. You also have a lab right?

Linux AD computer object operating system values
Fill out the operating system info for pre-staged computer objects of Active Directory joined Ubuntu servers

Actually we need PowerShell Core

Now, this all very good and well, but how do we find out the values for the operating system. During deployment, we know, but over time they will update and upgrade. So it would be nice to figure out those values automatically and remotely.

PowerShell Core to the rescue! With PowerShell Core, we can do PowerShell Remoting Over SSH to run a remote session on our Linux server over SSH and get all the information we need. To make this automation-friendly you must certificate bases authentication for your SSH connection. Setting that up can be a bit tricky, especially on Windows. That is a subject for a future blog post I hope. You can also use the SecretStore to securely store the AD automation account credentials. Note that I also use a dedicated automation account on all my Linux systems for this purpose. Here is a “quick & dirty” code snippet to give you some inspiration on how to do that for Ubuntu.

#Grab the AD automation account credentials - please don't use a domain admin for this.
#Use a dedicated account with just enough privileges to get the job done.
$Creds = Get-Credential -UserName 'DATAWISETECH\dwtautomationaccount'
 
#Connect to a remote PowerShell session on our Linux server using certificate authentication.
#Setting this up is beyond the scope of this article but I will try to post a blog post on this later.
#Note you need to configure all Linux servers and desktops with the $public cert and allow the user to authenticate with it.
#We use a cert as that is very automation friendly! You will not get #prompted for a password for the Linux host.
$RemoteSession = New-PSSession -Hostname GRIZZLY -UserName autusrli
 
#Grab the OS information. Note that $PSVersionTable.OS only exist on PowerShell Core.
#which is OK as that is the version that is available for Linux.
 
$OS = Invoke-command -Session $RemoteSession { $PSVersionTable.OS }
 
#Grab the OSVersion.VersionString.
$VersionString = Invoke-command -Session $RemoteSession { [System.environment]::OSversion.VersionString }
 
#Clean up, we no longer need the remote session.
Remove-PSSession $RemoteSession
 
#Sanitize the strings for filling out the Active Directory computer object operating system values.
$UbuntuVersionFull = ($OS | Select-String -pattern '(\d+\.)(\d+\.)(\d)-Ubuntu').Matches.Value
$OperatingSystem = $UbuntuVersionFull.Split('-')[1] + " " + (($UbuntuVersionFull.Split('-')[0])).Substring(0, 5)
 
#Grab the Active Directory computer object and fill out the operating system values.
$Instance = (Get-AdComputer -Credential $Creds -Identity GRIZZLY -Server datawisetech.corp)
$Instance.OperatingSystem = $OperatingSystem
$Instance.OperatingSystemVersion = $VersionString
$Instance.OperatingSystemServicePack = $UbuntuVersionFull
Set-AdComputer -Instance $Instance

That’s it! Pretty cool huh?!

Conclusion

While you cannot edit the Linux AD computer object operating system values in the GUI you can do this via PowerShell. With Windows, this is not needed. This is handled for you. When joining Ubuntu to Active Directory this only gets set if you do not pre-stage the computer accounts. When you do pre-stage them, these are left blank. I showed you a way of adding that info via PowerShell. The drawback is that you need to maintain this and as such you will want to automate it further by querying those computers and updating the values as you update or upgrade these Ubuntu servers. Remote PowerShell over SSH and PowerShell Core on Linux are your friends for this. Good luck!

Azure Done Well Means Hybrid Done Right

If you think that a hybrid cloud means you need to deploy SCVMM & WAP you’re wrong. It does mean that you need to make sure that you give yourself the best possible conditions to make your cloud a success and an asset in the biggest possible number of all scenarios that might apply or come up.

DC1

Cool you say, I hear you, but what does that mean in real life? Well it means you should stop playing games and get serious. Which translates into the following.

Connectivity

A 200Mbps is the absolute minimum for the SMB market. You need at least that for Office 365 Suite, if you want happy customers that is. Scale based on the number of users and usage but remember you’ll pinch at least a 100Mbps of that for a VPN to Azure.

Get a VPN already!

Or better still, take the gloves off and go for Express Route. Extend your business network to your cloud and be done with all the hacks, workarounds, limitations, tedious & creative yet finicky "solutions" to get thing done. I guess it beats living with the limitations but it will only get you that far.

Any country or business that isn’t investing in FC to the home & cheap affordable data connectivity to the businesses is actively destroying long term opportunity for some dubious short term gain.

So without further ado, life is to short to do hybrid cloud without. It opens up great scenarios that will allow you to get all the comforts of on premise in your Azure data center such as …

Extend AD  & ADFS into Azure

Get that AD & ADFS into the cloud people! What? Yes, do it. That’s what that good solid VPN between Azure and on premises or better still, Express Route enables. Just turn it into just another site of your business.  But one with some fascinating capabilities. DirSync or better Azure Active Directory Sync will only get you that far and mostly in a SAAS(PAAS) ecosystem. Once you’ve done that the world is your oyster!

https://media.licdn.com/mpr/mpr/p/4/005/083/346/127f314.jpg

Conclusion

So don’t be afraid. Just do it!  People I have my home lab and it’s AD connected to my azure cloud via VPN! That’s me the guy that works for his money and pays his own bills. So what are you as a business waiting for?

But wait Didier, isn’t AD going away, why would I not wait for the cloud to be 100% perfect for all I do? Well, just get started today and take it from there. You’ll enjoy the journey if you do it smart and right!

“Your cloud, your terms”. Well that’s true.  But that’s not a given, you’ll need to put in some effort. You have to determine what your terms are and what your cloud should look like. If you don’t you’ll end up in a bad state. If you have good IT staff, you should be OK. If they could handle your development environment & run your data center chances are good they’ll be able to handle “cloud”. Really.

Consultants? Sure, but get really good ones or you’ll get sold to. There’s a lot of churning and selling going on. Don’t get taken for a ride. I know a bunch of really good ones. How do I determine this? One rule … would I hire them Winking smile

Exchange 2010 SP3 Rollup 5 Added Support for Windows Server 2012 R2 Active Directory

6 weeks ago (February 25th 2014) Microsoft finally took away the last barrier to upgrading some of our Windows Server 2012 Active Directory Environments to R2.  Most of them are still running Exchange 2010 SP3 and not Exchange 2013. The reason is that Exchange 2013 was not deployed is whole other discussion Eye rolling smile.

However that dis mean that until the release of  Exchange Server 2010 SP3 Update Rollup 5 last month we could not upgrade Active Directory to Windows Server 2012 R2. Rollup 5 brought us support for exactly that. We can now:

  • Support Domain Controllers running Windows Server 2012 R2
  • Raise the Active Directory Forest Function Level and Domain Functional Level to Windows Server 2012 R2

Please note that you cannot deploy Exchange Server 2010 (SP3 RU5) on Windows Server 2012 R2 and you’ll probably never will be able to do that. I’m not sure Microsoft has any plans for this.

Now our office moves have been concluded, meaning I can get back to IT Infrastructure instead of being an glorified logistics & facility peon, we’re doing the upgrade.

This also means we can move the Active Directory environments to the latest version so we have the best possible position for any future IT projects at very low risk. The environments are already at W2K12 functional level. If the budgets get so tight they lose/scrap EA or volume licensing it also allows them to run at this level for many years to come without causing any blocking issues.

Reverting the Forest & Domain Functional Levels in Window Server 2008 R2, 2012, 2012 R2

Since Windows Server 2008 R2 and now with Windows Server 2012(R2)you can roll back the domain and forest functional level under certain conditions. This was not possible before with previous versions of Windows. In these cases you would have to revert to a restore from backup. Yup pretty hefty so raising functional levels has to be done with care.

Now this isn’t a free fire zone there are some conditions as listed in the table below.

image

So you cannot have advanced features like the AD recycle bin enabled in some conditions. Enabling this is irreversible, so you cannot revert the Forest Functional Level of your environment to a level that supports the AD recycle bin when it has been enabled. Today that means from Windows Server 2012(R2) to Windows Server 2008 R2.

You also need Enterprise Administrator rights to do so, which I hope you’ll understand. It’s also a Windows PowerShell only feature (Set-ADDomainMode).

I used this information recently during an upgrade of an Windows Server 2008 R2 domain to Windows Server 2012 where they wanted to raise the domain and forest functional level. As they had a Forest Trust between the (now) Windows Server 2012 forest/domain and another Windows Server 2008 R2 forest/domain. They had enabled the Recycle Bin when still at Windows 2008 R2. They wanted to know if they would have issues with the trust and if so whether they could revert the levels in that case.

Well I could put their mind at ease. Look at the table. Yes you can go back to Windows 2008 R2 Forest Functional level as that’s a version that also supports AD Recycle bin so it doesn’t matter that is enabled.  And no, the forest trust capability is not affected by the forest functional level in this case as all you need there is to be at a minimum level of Windows 2003 to be able to do a forest trust. Forest Trust is enabled from and above Windows Server 2003 Forest functional Level. In a Windows Server 2000 Forest functional Level, Forest Trust is disabled. That means you can do them between forests at different functional levels a long as non of them is lower than Windows 2003. In this case it’s Windows 2008 R2 that’s the lowest, so again, not an issue.

How? Very simple:

Set-ADDomain Mode mydomain.com -DomainMode Windows2008R2Domain

Set-ADForestMode mydomain.com -ForestMode Windows2008R2Forest

Take a look at these TechNet Resources Understanding Active Directory Domain Services (AD DS) Functional Levels  and Set-ADDomainMode for more information.