This answer to theCleaner's question helped me some Windows DHCP Server – get notification when a non-AD joined device gets an IP address but the answer to his question involved Quest Poweshell cmdlets. I would like to achieve a solution with plain old Powershell v4 cmdlets.
Problem
I currently receive no notification of new DHCP leases at all. I would like to receive notifications when someone plugs into one of our jacks here, gets a DHCP lease from our Windows Server 2012 DHCP server, but hasn't been AD-joined. So I want an email notification of new DHCP leases for non-AD joined devices.
What I've tried
I have put together some Powershell code, borrowing some from theCleaner's question mentioned above.
Get-DhcpServerv4Lease -allleases -ScopeId #myscopeIDhere | Select-Object @{expression= {$_.hostname}; label='name' } | export-CSV -notypeinformation C:\dhcp\LeaseLog.csv
import-module activedirectory
#get input CSV
$leaselogpath = "c:\DHCP\LeaseLog.csv"
Import-csv -path $leaselogpath |
#query AD for computer name based on csv log
foreach-object `
{
$NameResult = Get-ADComputer -Filter *
If ($NameResult -eq $null) {$RogueSystem = $_.name}
$RogueSystem | Out-File C:\DHCP\RogueClients.txt -Append
$RogueSystem = $null
}
Get-Content C:\DHCP\RogueClients.txt | Select-Object -Unique | Out-File C:\DHCP\RogueClientsFinal.txt
Remove-Item C:\DHCP\RogueClients.txt
#send email to sysadmin
$smtpserver = #my email server IP address here
$from="abcd@abcdefg.com"
$to="sysadmin@abcdefg.com"
$subject="Non-AD joined DHCP clients"
$body= (Get-Content C:\DHCP\RogueClientsFinal.txt) -join '<BR> <BR>'
$mailer = new-object Net.Mail.SMTPclient($smtpserver)
$msg = new-object Net.Mail.MailMessage($from,$to,$subject,$body)
$msg.IsBodyHTML = $true
$mailer.send($msg)
I receive the email "Non-AD joined DHCP clients" but there are no objects in the email. We do have non-AD joined DHCP leases (I connected a non-AD laptop the network for testing), but the laptop doesn't show in the email. I don't receive any red test after running the script either.
If anyone has suggestions please let me know. I obviously have something wrong somewhere in my script. I personally think it might have to do with my AD cmdlets and the CSV import.
Best Answer
This query will return all computers in AD, and its result will never be empty; you should query for the actual computer name you are trying to find:
Also, the names in the DHCP log files will likely be FQDNs (such as
computer.domain.local); if this is the case, you need to strip the domain suffix before feeding them into Get-ADcomputer, which only wants the computer name: