Monthly Archives: March 2018

Import and set TSGateway / RDGateway certificate with Powershell

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

 

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

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.