Author: HoundTech

Convert DHCP Lease to Reservation with Powershell

Scenario :  You have just created (by whatever means) a new server. It has gotten an IP address from DHCP and all is working as it should…..However…. Perhaps this server provides a service that requires a static IP (for whatever reason).

In the old days, you would fire up the DHCP tool from the RSAT tools or <shudder> RDP into your domain controller to convert the dynamic DHCP Lease into a reservation. There is a faster way…… if you guessed Powershell – you are correct 🙂

It took a little spelunking around to work this out but here are the steps to follow.

First, create a remote powershell session to your DHCP server.

 Enter-PSSession -ComputerName MyDC.houndtech.pri 

Next find out the IP address  of the new server. Easy enough with :

Test-NetConnection -computername Newserver.houndtech.pri 

Let’s make things a little easier for later and put that returned object in a variable.

$x = Test-NetConnection -computername Newserver.houndtech.pri  

But we don’t need the whole object, just the IP address, so let’s narrow it down with

$IP = $x.BasicNameResolution.IPaddress  

Now $IP contains JUST the IP address, which is what we need for the next series of cmdlets.
Next we retrieve the DHCP lease object with

 Get-DHCPServerV4Lease -IPAddress $IP 

Finally pipe it to the cmdlet to add the reservation.

 Get-DHCPServerV4Lease -IPAddress $IP | Add-DHCPServerV4Reservation 

Of course this could be piped together into a sweet oneliner that would go well added to any automated provisioning script.

 Get-DHCPServerV4Lease -IPAddress ((Test-NetConnection -ComputerName 'NewServer.HoundTech.pri').RemoteAddress.IPAddressToString)| Add-DhcpServerv4Reservation 

See you next time!

Powershell and Devops Summit 2018

Last week was the big Powershell/Devops Summit in Bellevue, WA. I say “big” not as in ginormous 15,000 attendee extravaganzas like Ignite or VMWorld. No, this 365 attendee Summit was big as in the stature of the people there. All the Powershell superstars were there, sharing their knowledge and enthusiastically pushing the rest of us to excel.

This was my first Summit, and although I have waded into the Powershell Community pool, this was a dive into the deep end! Happily, I managed to keep up and learn quite a few things that I can immediately apply. I also brought back copious notes on things to try out in the old Lab.

It would be a novella to describe all the things I learned, but here are a few highlights and key takeaways.

  • Powershell 6.x is the way forward. Cross-platform and lightweight, it will run on almost anything. There was a demo of a Raspberry Pi with Powershell 6 installed and sending sensor information ( heat – humidity sensor) and controlling an attached light. Pretty nifty. Also Cloud Shell (Azure Powershell in a browser) either runs now or will soon run v6.
  • To utilize old modules, soon to be released: Windows Powershell Compatibility Pack. This is a clever solution. It allows you to essentially remote into your own PC’s Windows Powershell (5.1) session. It’s a little confusing until you remember that Powershell 6 and Powershell 5.1 are different executables and can and do run side by side.
  • Powershell Classes + REST API’s = Super functions. In a nutshell, use  classes to build objects out of data returned from Get-RestMethod. Once it’s a fully fleshed out PSObject, you have many more options on how to interact with that data. Powershell is all about objects afterall. For more info: Tweet to: Jeremy Murrah or check out his presentation on GitHub
  • Desired State Configuration Pull Server is becoming more of a community/open source project. It appears (and maybe I misunderstood) that Microsoft isn’t doing much development on the Pull Server portion of DSC. They are focusing on the Local Configuration Manager (LCM). This makes a lot of sense, it’s easy and not expensive to use Azure Automation as your pull server. There are also a few other Open Source Pull servers like TUG
  • Lean Coffee! For a completely not  Powershell side session, Glenn Sarti introduced a few of us to ‘Lean Coffee’. It’s not a skinny half-caf soy latte, it’s a way to organize small informal meetings. Briefly, everyone gets Post-Notes ( or other slips of paper) and writes down 2-3 things they want the group to discuss at this meeting. Everyone votes on what they want to discuss and that determines the order of conversation. Someone acts as ‘timekeeper’, and every 2 minutes polls the group for a simple “thumbs up/down” vote. If the majority votes UP , the conversation stays on that topic, otherwise, you move on to the next highest voted topic. Repeat until time or topics runs out. I am definitely going to try this in our next team meeting! For more info – check out :
  • I learned a LOT about CI/CD pipelines for Powershell using VSTS and a few other tools from both and in separate sessions. This topic needs a blog post or 6 all it’s own. Two things to remember – 1. it can start simple and build from there  and 2. Plaster frameworks make the dream work.
  • Thomas Rayner showed us how to make custom rules for PSScriptAnalyzer. Time to make some “house rules”!

There was a LOT more that I have noted to study up on and try out, those will be later posts I’m sure.

Of course, Jeffrey Snover  continues to amaze me with his enthusiasm and optimism. Some great ‘Snover-isms” heard: “Line noise should not compile!” and “Like cockroaches in a kitchen full of cowboys”.

Aside from actual sessions, there were several interesting conversations not only with superstars like Don Jones™ and Mark Minasi, but also with the “next-gen” stars like Michael Bender and James Petty and with regular Powershell guys like me.

As for the actual event, the folks that put this together are top-notch. They care about the experience we have and it shows. Very good food, opportunities to socialize, and a refreshing lack of hard sell vendors. One of the few conferences I go to that doesn’t result in an email flood in the week following.

Bellevue was great – it only rained 4 of the 5 days I was there! Seriously though, the rain wasn’t an issue – even though I walked everywhere except to and from the airport. A light misting drizzly rain wasn’t horrible, and the temperatures were great. Cool enough so that you could vigorously walk up hills without getting sweat soaked and warm enough that only a light jacket was needed.


Powershell Tuesday Quick Tip #6

This week’s tip is a bit longer – it’s actually a little script to remotely create a shortcut to a network file share on a user’s desktop. This one comes in handy when explaining how to make a shortcut over the phone proves …. difficult.

$PC = ''
$User = 'LSkywalker'
$TargetPath = "\\\death_star_plans\"
$ShortcutFile="\\$PC\C$\Users\$user\Desktop\Death Star.lnk"
$Obj = New-Object -COMObject Wscript.Shell
$Shortcut = $Obj.CreateShortcut($ShortcutFile)
$Shortcut.TargetPath = $TargetPath

This one is a good candidate for getting wrapped up in a function and added to an “Admin Toolkit Module”.

Powershell Tuesday Quick Tip #5

Here’s another one from the easy but annoying to rethink stack.
People, as someone once said, are ‘squishy and move around a lot’. Not only do they move but they change and sometimes the change involves their names.
For example, the customer service person gets married or the sales manager gets divorced.(Hopefully not for the same reason – but that’s a different blog)

So you can either fire up the Active Directory tool of your choice (ADAC or ADUC) OR switch over to your PowerShell console that you have open already.
… you DO have it open already right?

Set-AdUser -Identity Leia -Surname 'Solo' -DisplayName "Leia Solo"
Set-Mailbox -Identity Leia -PrimarySmtpAddress '' -EmailAddressPolicyEnabled:$False -DisplayName 'Leia Solo' -EmailAddresses @{add =''}

The first line “Set-ADUser” changes Leia’s surname to Solo and corrects her display name. The second line, “Set-Mailbox” changes her primary email address to “” along with her display name while adding her original email address back in as an alternate. This is so Leia will continue to get email from some people that haven’t gotten the happy news yet.

These two lines require that you have the Active Directory module and a remote session to either Office365 or your Exchange server.

Next week I’ll be blogging from the PowerShell + DevOps Global Summit in beautiful Bellevue WA!


Powershell Tuesday Quick Tip #4

I know, I know- stop using RDP to manage devices. The fact is some tech support issues are solved faster and easier if you just remote into the user’s PC. This is particularly true in a small business where perhaps GoToAssist and other such tools are not in the budget.

But what if the pc doesn’t have RDP enabled? Today’s tip fixes that on domain joined machines.
First let’s check…

$PC = ""
#Determine if Remote Desktop is enabled - 1= enabled 0= Disabled
Get-WmiObject -Namespace 'root\cimv2\TerminalServices' -Class Win32_TerminalServiceSetting -ComputerName $PC -Property allowtsconnections|
Format-List AllowTsConnections

Ok so it came back with a 0, let’s correct that.

$PC = ""
(Get-WmiObject -Namespace 'root\cimv2\TerminalServices' -Class Win32_TerminalServiceSetting -ComputerName $PC).setallowtsconnections(1)

And done!

Once you’ve finished, if you want, reverse the process with a value of (0) for setallowedtsconnections

Of course – if you CAN, it’s even faster an easier to fix things with Powershell remoting. Sadly, not every application is PSAware 😦

See you next week!

Powershell Tuesday Quick Tip #3

Printer Tricks

This week is a 2-for-Tuesday! Two basic printer tricks.
These come in really handy when troubleshooting the “I can’t print” help desk tickets. Like a lot of these types of one-liners, you have to be in the same domain as the target pc.

First, we can get the printer queue for a pc.

$pc =''
Get-WMIObject Win32_PerfFormattedData_Spooler_PrintQueue -ComputerName $pc|
Select-Object Name, @{Expression={$};Label='CurrentJobs'}, TotalJobsPrinted, JobErrors

Secondly, there is this one to clear the printer queue

$PC = ""
get-wmiobject win32_printer -filter “Name='MyPrinterName'” -ComputerName $pc|
foreach {Write-verbose “Cancelling all jobs on $($_.Name)” $_.CancelAllJobs()}

*Note: For the “Clear Print Jobs” snip to work, you need to know what the printer is called on the target pc.

That one is handy for those times when someone has tried to print a poorly formatted file that puts the printer’s PCL logic into a tailspin. You can reboot everything but until you cancel that job, the printer will keep getting bogged down. It’s especially fun when you have 10+ people sharing a printer. This way you can wrap a “foreach” loop around the code and “Bob’s your uncle!”

Until next time!

Powershell Tuesday Quick Tip #2

This week is an easy one. Cleaning up Active Directory of old computers. Sometimes a machine gets retired or just completely craters and in the haste to get the user back up and going…. some clean up is forgotten. Easy to fix. this little snippet returns the time since PC has logged into the domain in DDD.HH:MM:SS format

$timespan = '90.00:00:00'
Search-ADAccount -AccountInactive -ComputersOnly -TimeSpan $timespan|
Foreach-Object {Write-output $} 

Of course it’s easy to add

 |Export-csv -Path C:\OLDPC.csv 

to the pipeline which gives you a CSV file to review and feed into a “Delete-OldComputer” oneliner!

See ya next week!