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Category Archives: Quick Tip

These short posts show how to do something very simply!

Search DHCP Scopes for a MAC – PowerShell Script

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Just a quick script that will prompt you for a MAC address and then search all DHCP server scopes for that value. You can input the MAC in any common format. Enjoy!

$DHCPServer = "DHCP-SERVER-NAME"

$InputMAC = Read-Host "Enter MAC Address"

# Remove any non-alphanumeric characters from the input MAC address
$FormattedMAC = $InputMAC -replace '[^0-9a-fA-F]', ''

# Format the MAC address as XX-XX-XX-XX-XX
$FormattedMAC = $FormattedMAC -replace '(.{2})(.{2})(.{2})(.{2})(.{2})(.{2})', '$1-$2-$3-$4-$5-$6'

$Scopes = Get-DHCPServerv4Scope -ComputerName $DHCPServer

foreach ($Scope in $Scopes) {
    Get-DHCPServerv4Lease -ComputerName $DHCPServer -ScopeId $Scope.ScopeId | Where-Object {$_.ClientId -EQ $FormattedMAC} | Format-Table -AutoSize
}

Freezing Processes in Task Manager – Quick Tip

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You open Task Manager to kill a stuck process. You try to right click and it dodges up. You try to highlight it, and it dives down. It’s is fully aware of what you are trying to do and will use all 5 D’s to stay alive.

Did you know that holding CTRL freezes all of those pesky processes in place? Go ahead – press CTRL+SHIFT+ESC to open Task Manager. Click on any Tab and press CTRL to freeze everything in place!

See? Paused! Or this is just a picture…

KList Purge and GPUpdate Security Group Members

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Security Group membership changes require a reboot before a computer can apply them. This prevents any newly filtered and scoped GPOs from applying as well. A past article showed how to use the built-in Klist tool to refresh the machine ticket and avoid that reboot.

But what if you need to KList Purge a bunch of computers? The script, below, will purge/refresh the system ticket and run a GPUpdate on all computers in a security group.

You could string together the psexec commands into a single line or call the commands as a batch file to make it more efficient. For simplicity of sharing, I left it as two separate commands.

Enjoy!

Write-Host "This script will refresh the system token and gpupdate all computers in a group."
$GroupName = Read-Host "What is the group name?"

$ADGroup = get-adgroup -Identity $GroupName

if ($? -eq $true){

    $Computers = Get-ADGroupMember -identity "$GroupName" -Recursive  | Where ObjectClass -eq computer

    Write-Host $GroupName contains $Computers.Count devices. Press enter to refresh the token and gpupdate this group.
    pause

    foreach ($Computer in $Computers){
        $ComputerName = $Computer.Name
        write-host $ComputerName
            &psexec.exe \\$ComputerName -accepteula -d -h -s -n 2 "c:\windows\System32\klist.exe" -li 0x3e7 purge
            &psexec.exe \\$ComputerName -accepteula -d -h -s -n 2 "c:\windows\System32\gpupdate.exe"
    }
}

The Best Trick I’ve Learned This Year

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Like everyone of you, this year has been filled with some challenging projects! We’ve migrated redirected folders to OneDrive, converted old Exchange groups to Teams that still sync from AD, set Teams to install and silently login, configured a new helpdesk and asset program, deployed a whole lot of new equipment, and countless other smaller projects.

Out of all of these projects, the best trick that I’ve learned this year is to create an email rule to move everything with the word “unsubscribe” in it to Junk (with a rare exception).

Outlook rule that moves emails with the word unsubscribe to junk.

The few unsolicited sales emails that still come through get their domains added to our mail filter block list.

No one has time for that crap.

Finding Unconfigured Aerohive APs with PowerShell

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Every now and then, an unconfigured Aerohive AP will pop up in our environment. These access points won’t work until their serial number is enrolled into our HiveManager first.

Finding an unconfigured AP is easy with PowerShell, provided you are using a universal naming convention with existing devices. Because configured APs are named SITE-ROOM-AP01, we can look for DHCP leases that match the default Aerohive AP naming scheme.[note]It is so nice to be able to ping/SSH into an AP without having to look up an IP.[/note]

Here is a script that will look in all DHCP scopes on a server and return any lease that ends with a dash and half a MAC address (ex: AH-0Fa1B3). You will need to change the first two lines to match your environment and you will need the DHCP cmdlets, which are installed with RSAT.

$DHCPServer = 'DHCP-Server-01'
$DOMAIN = 'domain.local'

$Scopes = Get-DhcpServerv4Scope -ComputerName $DHCPServer

foreach ($Scope in $Scopes){

$ScopeID = $Scope.ScopeID
$Leases = Get-DhcpServerv4Lease -ScopeId $ScopeID -ComputerName $DHCPServer | Select-Object HostName,IPaddress,ClientID

$Regex = '([-])([0-9A-Fa-f]{6})(.' + $DOMAIN + ')$'

    foreach ($Lease in $Leases){
        if ($Lease.HostName -match $Regex -eq $True){
            Write-Host $Lease.IPAddress , $Lease.hostname
        }
    }
}

If you have any problems running this script or improvements to it, just leave a comment!