All posts by Kirill Nikolaev

Small update to my DNS Synchronizer script

I’ve just released a small improvement to my DNS Synchronizer script. The update includes:

  1. Corrected the issue where sub-records of a record prevented that record to be synchronized.
  2. Corrected the way how start and end times are formatted — now they both are formatted equally.
  3. But the most significant one for the end-user, is that the script has been renamed to Sync-DNSZones, in accordance with PowerShell best practices.

If you execute the Get-Verb cmdlet w/o parameters, you’ll see that there is no “Synchronize” verb in the output — that’s why I renamed the script. Do not forget to rename “-NS” an “-REC” files accordingly.

Function to test a date against different conditions

Several weeks ago, my friend Rich Mawdsley asked our Windows Admins Slack team, how to tell if today is the second Tuesday in the month? As we found out, there is no built-in way in PowerShell to determine that. That’s why I present you today a function built specifically to test dates against different conditions. The function can tell you:

  • If the date is a certain weekday in a month. 4th Monday, Second Thursday, last Sunday etc.
  • If the date belongs to a certain quarter of a year.
  • If the date is a start or an end of a quarter.
  • If the date is the last day of a month etc.

Mind, that the output is boolean: the function will not tell you much about the date object, but only does it meet conditions or does it not. It returns $true if the date meets the conditions and $false in all other cases.

Here’s the code of the function, and, of course, you can always find the latest version at my GitHub:

The function covered with tests (you can see the results here), but not completely — I shall certainly improve this in the future. And yes, those tests have already helped me to fix several bugs before the official release 😉

BTW, If you haven’t written tests for your PowerShell code, I found this Introduction to testing with Pester by Jakub Jares very useful — you will start writing tests in Pester before the end of the lecture.

Building Highly-Available Windows Infrastructure: Command-line Style. AD DS. Part 2 — Post-Config

Previous part — Building Highly-Available Windows Infrastructure: Command-line Style. AD DS. Part 1 — Installation


In this post we will perform two configurations on our Active Directory Domain Services instance: We’ll define security tiers which later become cornerstones of our privilege delegation principles and we’ll tune domain-joining parameters. Also a quick tweak for the DNS service.

Continue reading Building Highly-Available Windows Infrastructure: Command-line Style. AD DS. Part 2 — Post-Config

Building Highly-Available Windows Infrastructure: Command-line Style. AD DS. Part 1 — Installation


Up to this day, Active Directory Domain Services (AD DS) has been the core of the Windows infrastructure. With each release of Windows Server, AD DS receives new features while keeping great backward compatibility. Windows Server 2016 brings following enhancements to AD DS:

In this blog we shall install the corner stone of our future infrastructure: a highly-available AD DS instance of two domain controllers. Our AD DS layout is going to be quite simple: two writable domain controllers in a single site.

Continue reading Building Highly-Available Windows Infrastructure: Command-line Style. AD DS. Part 1 — Installation

Building Highly-Available Windows Infrastructure: Command-line Style

Several months ago Windows Server 2016 was released. With this release Microsoft has made two significant changes in Windows Server installation options:

  • Nano Server was introduced
  • Server with a GUI now includes desktop experience features (it is even called “Server with Desktop Experience”) and there is no supported way to remove them. This should force IT Administrators to deploy Server Core more broadly.

Looks like now is a good time to stop thinking about Windows Server as a GUI based system and pivot your management approach to be more command-line.
This post is the first in a series of how to build your own highly-available Windows infrastructure using just PowerShell and some other command-line tools. I plan to discuss the following components:

  • Active Directory Domain Services,
  • Active Directory Certificate Services,
  • Desired State Configuration,
  • Key Management Services,
  • DHCP,
  • SCDPM,
  • SCCM,
  • Exchange Server,
  • And, possibly, S4B Server, as well.

I am not able to deploy Hyper-V hosts yet, as all my infrastructure is purely virtual and the host machine, sadly, is running Windows Server 2012 R2 and currently it is impossible for me to upgrade it.

All PowerShell code will not use any hardcoded values. Instead, at the beginning of each post, I shall include a set of variables which will allow you to easily recreate the infrastructure in your environment w/o any change in the code.

The first part is already here! Building Highly-Available Windows Infrastructure: Command-line Style. AD DS. Part 1 — Installation

Huge refactoring of Synchronize-DNSZones.ps1

Today I finished huge refactoring of my Synchronize-DNSZones script (see more about it here). The main reason to refactor was to introduce a support to synchronize zone-level records. To efficiently achieve this, I converted a huge pile of code into several smaller functions. I also improved code readability by PS 3.0 standards (apparently, it is also StrictMode-compatible now).
I improved error handling by introducing 3 new error events:
55 – DNS-zone creation is not yet supported. (And I don’t think I’ll ever support it)
72 – Function New-DnsRecord failed.
82 – Cannot import DNSClient PowerShell module.

I finally replaces unapproved verbs in function names to approved ones (see Get-Verb). I shall change the name of the script itself later.
Fixed an issue when Receive-DnsData sometimes returns empty response and.
Fixed typos and incorrect error handling and slightly enhanced comments.
And I also added forgotten definition of $SMTPCc variable.

In the future I plan to add ShouldProcess support (WhatIf).

Pull-requests / issues are welcome!

LAPS presentation

Last December I was presenting at Moscow IT Pro UG about Microsoft LAPS. Finally, the record of the presentation is processed and available at YouTube:

Do not forget to enable English subtitles (they are NOT auto-translated :D)

You may find PPTX-file here.

After the presentation, I was asked a couple of questions:
Q: Does the GUI tool send the password in plain text over the network?
A: No, LDAP connection is encrypted with SASL. But if you are going to access the password attribute in your own scripts/tools, you may accidentally expose the password if you set LDAP_OPT_ENCRYPT = 0 or will use ldap_simple_bind w/o TLS/SSL.

Q: Why do we even need those local accounts? Why not to disable them completely?
A: In case a machine has lost its connection to AD (due to network configuration change, for example), you may want to bring it back on line w/o disruptive actions such as reboot, offline password reset etc. In case if you hope that the machine keeps your offline password hash, you may find yourself in a stressful situation, when you find out that it, in fact, does not.

Google Glazier

WOW, Google has just released a tool to automate the installation of the Microsoft Windows. The tool is written in Python and is called Glazier. OS images are built using text-based YAML config files which are easy to store in a source control system — in that case you can easily review change history and comments, rollback, compare etc.

All data are transferred via HTTPS, which enables you to deliver them anywhere, utilize CDN caches etc.

The tool is distributed by Apache 2.0 license, pull requests are welcome.

Blogs to follow

Today I want to share with you a list of blogs which I personally read and follow. Almost all of them are maintained by recognized individual IT professionals, many of them hold Microsoft MVP and similar awards.
I highly recommend you to add these blogs into your RSS/news-reader.

Of course I read a significant part of the TechNet/MSDN fleet too, but you, for sure, already know all the important ones, so I’ll leave them out for now.

If you have similar lists — share them with us in the comments.

SCDPM in a tiered infrastructure

When a company has a secure infrastructure, usually there are several tiers of resources managed by different administrators (or, at least, by same administrators but using different user accounts). For example, one may separate sensitive servers, like PKI Certification Authorities, Hyper-V hosts or file servers containing PII, and mark them as Tier 1 servers, while marking all other servers as Tier 2. Then he sets up permissions in a way that each tier has its own local administrators, and you may even forbid cross-tier logon completely (except network logon – network logon is useful and doesn’t pose a security threat).

In the ideal world you would have separate management solutions for each tier. But we all live in real world and, sometimes, it is impossible to find additional resources to support your infrastructure. In that case, it is more appropriate to designate your management servers, including backup ones, as Tier 1 – this way more secure servers will be able to access resources residing on less secure servers but not vice versa.

What does this mean for SCDPM? DPM wasn’t designed to backup resources from another security tier, but we can bent it to our will.
After you install an SCDPM agent on a server in Tier 2, then you must attach it to an SCDPM server in Tier 1. At this step, a user, which you are using to attach the agent, must be a local administrator at both the server and the client. Considering our tiered infrastructure, this is impossible, as one user cannot be a member of local administrators on machines from different tiers.
Fear not! We shall grant required permissions granularly in two steps:

Step 1

Basically we need to allow following permissions for Tier 1 admin at Tier 2 server’s WMI root and propagate them through the tree:

  • Enable
  • MethodExecute
  • RemoteAccess
  • ReadSecurity

You may choose to assign these permissions either via GUI, using wmimgmt.msc, or using PowerShell.
For PowerShell way you may use this fixed version of Set-WmiNamespaceSecurity.ps1 script. Original, written by Steeve Lee, suffers from a bug which does not allow to set inheritance flag and throws an error: “Invoke-WmiMethod : Invalid parameter”.
Run PowerShell script at the Tier 2 client as follows:
Set-WmiNamespaceSecurity.ps1 -namespace 'root' -operation 'add' -account 'EXAMPLE\tier1-admin' -permissions 'Enable','MethodExecute','RemoteAccess','ReadSecurity' -allowInherit $true

If you are going to set permissions with a GUI, here’s how it should looks like:

Step 2

This is counter-intuitive one: As we know, SCDPM server requests the time zone from an agent and saves it in the database. Sometimes, somehow, step 1 is not enough for remote non-admin user to request computer’s time zone. As a workaround, execute following WMI query at an SCDPM client: select * from Win32_TimeZone. After that, remote non-admin user will be able to request TimeZone instances for some time.
To utilize PowerShell for the task, execute this: Get-WmiObject -Query 'select * from Win32_TimeZone'

After these two steps, you should be able to add Tier 2 agent under protection of Tier 1 SCDPM server. When you have finished, you may safely remove those permissions by running the following command:
Set-WmiNamespaceSecurity.ps1 -namespace root -operation delete -account 'EXAMPLE\tier1-admin'