Category Archives: Powershell

Shutdown Storage Spaces Direct (S2D) or Azure Stack HCI Hyper-Converged cluster safely

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Yes, we are building clustered solutions to keep as high uptime as possible but sometimes there is a planned or unplanned electrical outage or maintenance work on power lines when we are simply forced to shutdown our cluster – and in that situation we want to do it safely.

When we talk about Storage Spaces Direct (S2D) on Windows Server 2016 / 2019 / 2022 in a hyper-converged scenario (when hyper-v virtualization and storage are inside the same system) it is very important to take care of properly shut down such system not to get in problematic situations where data corruption or some other issues could emerge. Becouse of that Microsoft has a great article about how to safely and properly shutdown a node in S2D configuration.

I would like to share with you a concept that could help you with getting whole cluster safely turned off.

Scenario consists of 2-node S2D solution, standalone hyper-v (on which I run file share witness (for S2D)) and PRTG that by using SNMP monitors APC UPS 2200:

So first of all we need to get the information about Battery capacity by using SNMP query to APC Network management card – this will be the value that we will monitor and based on the current value we will trigger some actions.

Then we need to prepare Notifications templates where we define Powershell scripts to be executed.
I am using three scripts:
– First script will make a graceful stop of storage services and put S2D Cluster N2 in maintenance mode (all roles will be drained to S2D Cluster N1) after that it will shut down S2D Cluster N2
– Second script will trigger shutdown of all virtual machines on S2D Cluster N1 and after 180 seconds it will shut down the S2D Cluster N1
– Third script will shut down third hyper-v host (standalone)

With the action Execute Program on our Notification Template we define which script we would like template to use and username and password that will be used only to execute the script on local machine (PRTG) – credentials for powershell remoting that will do the shutdown jobs can be safely saved separately so you do not need to enter plain-text credentials to access the hosts anywhere.

After that we need to configure triggers – when scripts will be executed based on the battery capacity – so in my case I decided to set it up like this:

  • When battery is on 65% turn off S2D Cluster N2 (drain roles (VMs and cluster service roles to S2D Cluster N1), put the node in maintenance mode, shut down the physical node S2D Cluster N2).
  • When battery is on 45% turn off S2D Cluster N1 by firs shutting down all VMs, than wait 180 seconds for shutdown to complete and then shut down physical S2D Cluster N1.
  • When battery is on 15% turn off standalone Hyper-V host – where our Witness and PRTG VMs are running

If we check the scriptblocks inside our scripts:

Shutdown-N2.ps1 (the script that in my case we will run first):

In first part of the script we need to setup credentials that will be used to execute powershell remoting:
You can do this buy simply entering username and password into the script (Please do not do that! Powershell allows you to do it way more securely. Please read this article about securely saving encrypted password in separate file.

Invoke-Command -ComputerName S2D-N2 -Credential $credential -ScriptBlock {
$nodename = ‘S2D-N2’
Suspend-ClusterNode -Name S2D-N2 -Drain -Wait
Get-StorageFaultDomain -type StorageScaleUnit | Where-Object {$_.FriendlyName -eq $nodename} | Enable-StorageMaintenanceMode
Stop-ClusterNode -name S2D-N2
Start-Sleep -Seconds 10
Stop-Computer -Force
}

Shutdown-N1ps1 (the second script that will be executed – this will turn off VMs and finaly S2D Cluster N1):

Invoke-Command -ComputerName S2D-N1 -Credential $credential -ScriptBlock {
Get-VM | Stop-VM -Force -AsJob
Start-Sleep -Seconds 180
Stop-Computer -Force
}

Shutdown-HyperV.ps1 (the third script that will turn off stand alone Hyper-V host):

Invoke-Command -ComputerName StandaloneHyperV -Credential $credential -ScriptBlock {
Stop-Computer -Force
}

So the shutdown sequence will be:
– when electricity is turned off and PRTG gets the info by querying UPS that capacity of the battery is under 65 %:
S2D Cluster – N2 will bi gracefully stopped (by draining roles and putting it in maintenance mode and shutdown after that)
– when the battery is under 45 %:
S2D cluster – N1 will be gracefully stopped (by shutting down all VMs and finally shutting down)
– when the battery capacity is under 15 %:
Our standalone host (where PRTG and File Share Witness (needed for S2D Cluster)) will be shutdown.

The procedure to turn the system back on is the following:
– First we will turn on standalone host (and Files Share Witness VM)
– Please do not turn on PRTG server until UPS battery capacity is not over 65% (because PRTG will turn on the procedures again if capacity is below 65%)
– When you checked that standalone host has network connectivity and File Share Witness VM is working and has connectivity too we can proceed further by turning on S2D Cluster N1
– When S2D Cluster N1 is up we can turn on VMs* (as Witness is there and N1 is fully functional you are able to start your production VMs – there will be more data to resync so if you have time it is better to wait for N2 to get back online and put it out of maintenance mode.)
– We can now turn on S2D Cluster N2 and when it comes back online we need to bring it back into fully functional Cluster member state by executing the script:

$ClusterNodeName = ‘S2D-N2’
Start-ClusterNode -name $ClusterNodeName
Get-StorageFaultDomain -type StorageScaleUnit | Where-Object {$_.FriendlyName -eq $ClusterNodeName} | Disable-StorageMaintenanceMode
Resume-ClusterNode -Name $ClusterNodeName -Failback Immediate

After executing the script you can check the progress of storage re-synchronization by executing Powershell cmdlet: Get-StorageJob

When UPS battery capacity reaches over 65% you can turn on your PRTG monitoring system again.

Add just some of available disks in storage pool (new-storagepool)

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If you follow the article on Microsoft on topic – New-StoragePool you will find out that it just takes all available disks that can be pooled into a variable.
If you want to add just some of available drives into a pool you should create arraylist of disks which you can populate by using just some drives identified by its UniqueId.
For example:

Get-PhysicalDisk -CanPool $true | ft FriendlyName, Size, UniqueId
[System.Collections.ArrayList]$disks = @(Get-PhysicalDisk -UniqueId 60022480015BE59BBBFBD5FBAF9A69DE)
$adddisk = Get-PhysicalDisk -UniqueId 60022480C6BE12F96745D63C63131D0D
$disks.Add($adddisk)
$disks | ft uniqueid 

“Poor man” monitoring of creation/enablement and addition and removal to/from security group of an account in Active Directory (part 2)

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Next step is to monitor addition and/or removal of user to/from security group – in this example I will show that alert is triggered when user is added to domain admins security group.
The script is a bit modified so it covers the user that added another user to a security group, a user that was added to a security group and which group user was added to.

$EventMessage = get-winevent -FilterHashtable @{Logname=’Security’;ID=4728} -MaxEvents 1 | fl TimeCreated, Message
$eventmessagetstring = $EventMessage | Out-String
$EventMessageAccountNameTextAdmin = $EventMessagetstring | Select-String -Pattern “Subject:\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+” -AllMatches | Select -ExpandProperty matches | Select -ExpandProperty value
$EventMessageAccountNameTextUser = $EventMessagetstring | Select-String -Pattern “Member:\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+” -AllMatches | Select -ExpandProperty matches | Select -ExpandProperty value
$EventMessageAccountNameTextGroup = $EventMessagetstring | Select-String -Pattern “Group:\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+” -AllMatches | Select -ExpandProperty matches | Select -ExpandProperty value
$EmailTo = “me@domain.com”
$EmailFrom = “alert@domain.com”
$Subject = “New user in Active Directory!”
$Body = “User was added to group by: `n $EventMessageAccountNameTextAdmin `n `n `n User that was added to securty group: `n $EventMessageAccountNameTextUser `n `n `n Security group user was added to: `n $EventMessageAccountNameTextGroup”
$SMTPServer = “YourSMTPServer”
$SMTPMessage = New-Object System.Net.Mail.MailMessage($EmailFrom,$EmailTo,$Subject,$Body)
$SMTPClient = New-Object Net.Mail.SmtpClient($SmtpServer, 25)
$SMTPClient.Send($SMTPMessage)

I have created new Task Scheduler task in which now I am calling new script that I have named SecurityGroup.ps1

All the other stuff is configured in the same way as written in my previous post.

security group

“Poor man” monitoring of creation/enablement and addition and removal to/from security group of an account in Active Directory (part 1)

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If you want to implement “poor man” monitoring of important events that can happen in your Active Directory like – creation of an user or in case if someone enables or disables an user account or if user is added to a security group (for example in domain admins) you can do it by using out-of-the box solutions that Windows Server provides.

Without touching any additional auditing (by using Group policy or Local policy) you can simply attach a task to events:

Event ID: 4720 – A user account was created.
Event ID: 4722 – A user account was enabled.
Event ID: 4725 – A user account was disabled.
Event ID: 4728 – A member was added to a security-enabled global group.

I find these events very important because if they are not triggered by an intentional creation / modification of an user in Active Directory it might mean that someone is making some unwanted and potentially dangerous changes (and we all know how devastating for our infrastructure can be if privileges escalate to Domain admins level).

So let’s use out-of-the box solutions to get information if such event happens.
We will use:
Event Viewer and the option to trigger an action of out the event id by using Task Scheduler and some Powershell scripting to get alert e-mailed to administrator.

On DC I have created a folder on c:\ps in which I have placed PS1 script called: NewUser.PS1
In the script I have some lines that parse newly created Event with ID 4720.

$EventMessage = get-winevent -FilterHashtable @{Logname=’Security’;ID=4720} -MaxEvents 1 | fl TimeCreated, Message
$eventmessagetstring = $EventMessage | Out-String
$EventMessageAccountNameTextAdmin = $EventMessagetstring | Select-String -Pattern “Subject:\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+” -AllMatches | Select -ExpandProperty matches | Select -ExpandProperty value
$EventMessageAccountNameTextNewUser = $EventMessagetstring | Select-String -Pattern “New Account:\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+” -AllMatches | Select -ExpandProperty matches | Select -ExpandProperty value
$EmailTo = “me@domain.com”
$EmailFrom = “alert@domain.com”
$Subject = “New user in Active Directory!”
$Body = “New user created by: `n $EventMessageAccountNameTextAdmin `n `n `n New user username: `n $EventMessageAccountNameTextNewUser”
$SMTPServer = “YourSMTPServer”
$SMTPMessage = New-Object System.Net.Mail.MailMessage($EmailFrom,$EmailTo,$Subject,$Body)
$SMTPClient = New-Object Net.Mail.SmtpClient($SmtpServer, 25)
$SMTPClient.Send($SMTPMessage)

This script is saved.

After that we run Task Scheduler and create new Basic task where Trigger is When a specific event is logged on next screen we chose as Log: Security then Source: Microsoft Windows security auditing. and we insert Event ID: 4720.

After that we need to chose Action: Start a program as Program/script: Powershell and in Add arguments (optional): -ExecutionPolicy ByPass -File c:\ps\NewUser.ps1

on Finish screen we can check checkbox Open the Properties dialog …

On General tab of task properties we can chose radio button: Run whether user is logged on or not and then checkbox Do not store password. The task will only have access to local computer resources.

If you try to create new user in AD in couple of seconds you should receive e-mail with alert where you get the user that created new user in AD and the actual username of the newly created user.

new user

In the video you can check the tasks described above.

 

(Mass) Modifying SOA record values by using Set-DnsServerResourceRecord

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Today I wanted to update all serial numbers (to make sure that are written in YYYYMMDD00 way) on my primary DNS zones on my Windows server 2019 DNS server.

This is the script to do this massive change – by using this script anyone can modify any parameters in DNS.

$allzones = Get-DnsServerZone | Where-Object -Property ZoneType -EQ -Value “Primary”
foreach ($allzone in $allzones) {
$old = “”
$new = “”
$old = Get-DnsServerResourceRecord -ZoneName $allzone.ZoneName -Name “@” -RRType Soa
$new = $old.Clone()
$new.RecordData.SerialNumber = 2019080400
Set-DnsServerResourceRecord -OldInputObject $old -NewInputObject $new -ZoneName $allzone.ZoneName -PassThru
}

Get e-mail alert for failed logon attempt on Outlook Web Access (OWA)

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Just for fun I tried to establish a mechanism that will allow me to get information for failed logon attempt on Outlook Web Access (OWA).

If you open event viewer on your CAS server (where OWA is located) you can find out that failed requests are logged with Event ID 4625.
003

001
In general information you can find interesting things like – username which was used and IPv4 or IPv6 address from where the attempt was made.
002
All you need to do is to Attach task to this event
004
As all other actions are deprecated you should use the option to Start a program – here we will run a Powershell script to do the job.
005
We need to create a PS1 (powershell script) with content:

$EventMessage = get-winevent -FilterHashtable @{Logname=’Security’;ID=4625} -MaxEvents 1 | fl TimeCreated, Message
$eventmessagetstring = $EventMessage | Out-String
$EventMessageAccountNameText3array = $EventMessagetstring | Select-String -Pattern “Account Name:\s+\S+” -AllMatches | Select -ExpandProperty matches | Select -ExpandProperty value
$EventMessageAccountNameText3 = $EventMessageAccountNameText3array[-1]
$EventMessageAccountNameText = $EventMessagetstring | Select-String -Pattern “Failure Reason:\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+\S+” -AllMatches | Select -ExpandProperty matches | Select -ExpandProperty value
$EventMessageAccountNameText2 = $EventMessagetstring | Select-String -Pattern “Source Network Address:\s+\S+” -AllMatches | Select -ExpandProperty matches | Select -ExpandProperty value

$EmailTo = “admin@domain.com”
$EmailFrom = “alert@domain.com”
$Subject = “OWA attack from $EventMessageAccountNameText2”
$Body = “Owa attack from: `n $EventMessageAccountNameText2 `n $EventMessageAccountNameText3 `n $EventMessageAccountNameText”
$SMTPServer = “IPOfYourSMTPServer”
$SMTPMessage = New-Object System.Net.Mail.MailMessage($EmailFrom,$EmailTo,$Subject,$Body)
$SMTPClient = New-Object Net.Mail.SmtpClient($SmtpServer, 25)
$SMTPClient.Send($SMTPMessage)

So in task properties we should choose:
007
In Add arguments (optional) field we should add:

-ExecutionPolicy ByPass -File X:\PathToScript\OwaAttack.ps1

So if everything is correct – next time someone fail to enter correct password or an attack on OWA is performed you will get an e-mail like this:

006

Implementing LAPS (local administrator password solution) in few simple steps…

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I would like to help you setting up LAPS in your environment – just follow this simple guide how to do it and say “bye bye” to not-secure fixed local administrators passwords.

First you need to download x64 (and if you need x86) LAPS from Microsoft website:
https://www.microsoft.com/en-us/download/details.aspx?id=46899

Download LAPS.x64.msi on your Active Directory domain controller and install it – add also Management Tools that are not selected by default:
Install LAPS

After installing it open Powershell on your DC, import Powershell module for LAPS, update AD Schema for LAPS (you need to be schema admin!), define OU where computers / servers that will be under LAPS management are, define user or group that will have privilege to read and reset password for client or server:

Import-Module AdmPwd.PS
Update-AdmPwdADSchema
Set-AdmPwdComputerSelfPermission -OrgUnit Clients
Set-AdmPwdResetPasswordPermission -Identity Clients -AllowedPrincipals “demo\domain admins”
Set-AdmPwdReadPasswordPermission -Identity Clients -AllowedPrincipals “demo\domain admins”

update schem

laps delegate control

Create group policy object on clients / servers OU (in my case with name LAPS) in which you will configure settings and deploy client on machines (yes, the MSI package that was installed on DC needs to be installed on workstations and servers too – the simplest way to do it is by using software deployment in group policy.

laps settings

LAPS deployment

Laps Deployment 2

Reboot your clients or use gpupdate /force to apply group policy settings and installation of the package.

If everything was installed and applied correctly you should see the installed package in programs on client workstation or server:

client install

On your AD server you can now check password by using Powershell or by using LAPS GUI:

Get-AdmPwdPassword -ComputerName w10 -Verbose

password - powershell

laps gu

password - ui

LAPS is great, simple and adds some more security in your environment.

 

 

Add-VMNetworkAdapterExtendedAcl – allow only specific traffic to a VM and allow all outgoing traffic from a VM on Windows server 2016 – Hyper-V

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Block all trafic to a VM:
Add-VMNetworkAdapterExtendedAcl –VMName “vm01” –Action “Deny” –Direction “Inbound” –Weight 10
Allow (for example) TCP 80 (HTTP) and TCP 443 (HTTPS) to a VM:
Add-VMNetworkAdapterExtendedAcl –VMName “vm01” –Action “Allow” –Direction “Inbound” –LocalPort 80 –Protocol “TCP” –Weight 11
Add-VMNetworkAdapterExtendedAcl –VMName “vm01” –Action “Allow” –Direction “Inbound” –LocalPort 443 –Protocol “TCP” –Weight 12
 
Allow any TCP and UDP from VM to ANY port and ANY address:
Add-VMNetworkAdapterExtendedAcl -VMName “vm01” -Action Allow -Direction Outbound -RemotePort Any -Protocol tcp -Weight 100 -IdleSessionTimeout 3600 -Stateful $True
Add-VMNetworkAdapterExtendedAcl -VMName “vm01” -Action Allow -Direction Outbound -RemotePort Any -Protocol udp -Weight 101 -IdleSessionTimeout 3600 -Stateful $True
 
Want to start over? Remove all ACLs:
Get-VMNetworkAdapterExtendedAcl -VMName “vm01” | Remove-VMNetworkAdapterExtendedAcl

Import and set TSGateway / RDGateway certificate with Powershell

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As I noted in my previous article Let’s Encrypt started to issue wildcard certificates – and now for me it is a right time to automate the whole process of renewal and binding – and I am using Let’s Encrypt certificates also for my RD Gateway servers (some of them stand-alone without other TS/RD roles).

So how to get from PFX certificate “package” (before retrived from Let’s Encrypt) to a fully functional RDGateway?

Be careful with providing password for certificate import – Inserting passwords into scripts is not a good idea! – here I have inserted it in souch way just for an example:

$pass = “passw0rdforimport” | ConvertTo-SecureString -AsPlainText -Force

Then we need to import certificate in LocalMachine certificate store and save its Thumbprint into a variable $Thumbprint that we will use later to bind it to TS/RDGateway

$Thumbprint = Import-PfxCertificate -FilePath C:\lets\certificate_combined.pfx -Password $pass -CertStoreLocation Cert:\LocalMachine\My | select -ExpandProperty Thumbprint

Next we need to create CertHash that will be inserted in RDGateway settings

$Cert = Get-Item -Path Cert:\LocalMachine\My\$Thumbprint
$CertHash = $Cert.GetCertHash()

As we have our CertHash we can set the setting for TS/RDGateway

Get-CimInstance -Namespace root/CIMV2/TerminalServices -ClassName Win32_TSGatewayServerSettings | Invoke-CimMethod -MethodName SetCertificate -Arguments @{CertHash = $CertHash}

To apply new settings we need to restart TS/RDGateway service

Restart-Service -Name TSGateway -Force

 

How to change TXT record value on Micorosft DNS server using Powershell

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As Let’s Encrypt anounced wildcard certificates I just wanted to make my life easier with automating the process of renewal and inserting values in TXT records to prove domain identity.

I am running all my DNS zones on Microsoft Windows server 2016 with DNS role installed where I will need to modify TXT record value every (little less) than three months to renew my *.domain.xyz cerificate. So how can we do it in Powershell just by modifing the existing value.

First time you will probably need to create the record by using:
Add-DnsServerResourceRecord

Add-DnsServerResourceRecord -Txt -Name _acme-challenge -DescriptiveText “SomeTextThatYouReceiveFromLet’sEncryptACME2Process” -ZoneName mydomain.xyz -TimeToLive 00:00:10

*I am keeping TTL very low here just in case you will need to repeat the process to expire soon (in 10 seconds).

Later on you will need just to modify the value of TXT record _acme-challenge
We have here a new cmdlet to the rescue: Set-DnsServerResourceRecord but it can not be simply used just to modify the value – you need to use two fill two parameter values called -OldInputObject (old record values) and -NewInputObject (new modified values).

Let’s take a look at the example:

$oldvalue = Get-DnsServerResourceRecord -ZoneName mydomain.xyz -RRType Txt -Name _acme-challenge
$newvalue = Get-DnsServerResourceRecord -ZoneName mydomain.xyz -RRType Txt -Name _acme-challenge
$newvalue.RecordData.DescriptiveText = “SomeNEWTextThatYouReceiveFromLet’sEncryptACME2Process”
Set-DnsServerResourceRecord -ZoneName mydomain.xyz -OldInputObject $oldvalue -NewInputObject $newvalue

What we did here is to declare two values where current values of the record are stored – $oldvalue and $newvalue.
Then I modified the $newvalue element called “DescriptiveText” that represents the text string of TXT record to some new data that I receive from ACME2 process when requesting Let’s Encrypt wildcard certificate.
At least I applied this new value to the record by using Set-DnsServerResourceRecord cmdlet and parameters.