Our deployment team needed a few DHCP options set for all our scopes. There was a brickload of these scopes, no way I was going to go to each one of them and right-click add the options! I figured this was one for PowerShell!
Yes, I ended up taking longer with PowerShell coz I didn’t know the DHCP cmdlets but hey (1) now I know! and (2) next time I got to do this I can get it done way faster. And once I get this blog post written I can refer back to it that time.
The team wanted four options set:
- Predefined Option 43 – 010400000000FF
- Custom Option 60 – String – PXEClient
- Predefined Option 66 – 10.x.x.x
- Predefined Option 67 – boot\x86\wdsnbp.com
PowerShell 4 (included in Windows 8.1 and Server 2012 R2) has a DHCP module providing a bunch of DHCP cmdlets.
First things first – I needed to filter out the scopes I had to target. Get-DhcpServerv4Scope is your friend for that. It returns an array of scope objects – filter these the usual way. For example:
|
1 |
Get-DhcpServerv4Scope -ComputerName MyDHCPServer | ?{ $_.Name -notmatch "Voice" -and $_.Name -notmatch "Wireless" } |
Now, notice that one of the options to be added is a custom one. Meaning it doesn’t exist by default. Via GUI you would add it by right clicking on “IPv4” and selecting “Set Predefined Options” then adding the option definition. But I am doing the whole thing via PowerShell so here’s what I did:
|
1 |
Add-DhcpServerv4OptionDefinition -ComputerName MyDHCPServer -Name PXEClient -Description "PXE Support" -OptionId 060 -Type String |
To add an option the Set-DhcpServerv4OptionValue is your friend. For example:
|
1 |
Set-DhcpServerv4OptionValue -ComputerName MyDHCPServer -ScopeId "MyScope" -OptionId 060 -Value "PXEClient" |
I had a bit of trouble with option 43 because it has a vendor defined format and I couldn’t input the value as given. From the help pages though I learnt that I have to give it in chunks of hex. Like thus:
|
1 |
Set-DhcpServerv4OptionValue -ComputerName MyDHCPServer -ScopeId "MyScope" -OptionId 043 -Value 0x01,0x04,0x00,0x00,0x00,0x00,0xFF |
Wrapping it all up, here’s what I did (once I added the new definition):
|
1 2 3 4 5 6 7 |
Get-DhcpServerv4Scope -ComputerName MyDHCPServer | ?{ $_.Name -notmatch "Voice" -and $_.Name -notmatch "Wireless" } | %{ $Scope = $_.ScopeId; Write-Host -ForegroundColor Yellow "Working on $Scope" Set-DhcpServerv4OptionValue -ComputerName MyDHCPServer -ScopeId $Scope -OptionId 043 -Value 0x01,0x04,0x00,0x00,0x00,0x00,0xFF Set-DhcpServerv4OptionValue -ComputerName MyDHCPServer -ScopeId $Scope -OptionId 060 -Value "PXEClient" Set-DhcpServerv4OptionValue -ComputerName MyDHCPServer -ScopeId $Scope -OptionId 066 -Value "10.x.x.x" Set-DhcpServerv4OptionValue -ComputerName MyDHCPServer -ScopeId $Scope -OptionId 067 -Value "boot\x86\wdsnbp.com" } |
And that’s it!