Menu wrapper for a few DHCP cmdlets

DHCPUtility.ps1

function Import-RemoteDhcpServerModule {
  param (
    $server
  )
  
  $Error.Clear()
  Write-Output "`nCreating remote session to $server..."
  
  try {
    $Script:Session = New-PSSession -ComputerName $server
    Invoke-Command -Command { Import-Module dhcpserver } -Session $Script:Session
    Import-PSSession -Session $Session -Module dhcpserver -AllowClobber
  }
  catch {
    Write-Host "Error establishing session to $server" -ForegroundColor Yellow
    Write-Host $Error[0].Exception.Message -ForegroundColor Red -BackgroundColor Black
    break
  }
}
function Select-DhcpDhcpServer {
  Clear-Host
  Write-Output "`nEnumerating DHCP Servers..."
  
  $DhcpServers = Get-DhcpServerInDC | Sort-Object -Property DnsName | Select-Object -ExpandProperty DnsName
  $htDhcpServers = @{}
  $DhcpServerList = "`n Available DHCP Servers"
  $DhcpServerList += "`n ----------------------`n"
  $i = 0
  
  foreach ($DhcpServer in $DhcpServers) {
    $htDhcpServers.Add($i,$DhcpServer)
    $i++
  }
  for ($x=0;$x -lt $DhcpServers.Count;$x++) {
    $DhcpServerList += " $x - $($htDhcpServers.$x)`n"
  }
  
  $DhcpServerList += " $($x+1) - Quit`n"
  $DhcpServerList
  
  do {      
    if ($null -ne $test) {
      Write-Output "`nIncorrect selection, please try again."
    }    
    $DHCPServerTarget = Read-Host -Prompt "Select the target DHCP server"
    $Script:SelectedDhcpServer = $htDhcpServers.[int]$DHCPServerTarget
    $test = $false
  } while ($DHCPServerTarget -notmatch "^([0-9]|[1-2][0-8])$")
  
  if ($DHCPServerTarget -eq $x+1) {
    $Script:ExitScript = $true
    return
  }
  else {
    $Script:ExitScript = $false
  }
  
  Import-RemoteDhcpServerModule -server $Script:SelectedDhcpServer
}

function Show-DhcpMainMenu {
  Clear-Host
  $MainMenuBadChoice = $false
  do {
    $MainMenu = @"

  DHCP Utility - Main Menu
  ------------------------

  1 - View details for a specific scope
  2 - View reservations for a specific scope
  3 - View statistics for a specific scope
  4 - View leases for a specific scope
  5 - View scope summary for current server
  6 - Add reservation
  7 - Convert existing lease to reservation
  8 - Delete reservation
  9 - Delete lease
  10 - Quit
  (Selected server: ${SelectedDhcpServer})

  Selection
"@    
    if ($MainMenuBadChoice -eq $true) {
      Clear-Host
      Write-Host "`nInvalid selection: $MainMenuSelection`n" -ForegroundColor Yellow
    }
    $MainMenuSelection = Read-Host -Prompt $MainMenu
    $MainMenuBadChoice = $true
  } while ($MainMenuSelection -notmatch "^([1-9]|10)$")
  
  switch ($MainMenuSelection) {
    '1' {
      $Error.Clear()
      $TargetScopeId = Read-Host -Prompt "`nEnter the IP address (network ID) for the scope"
      Get-DhcpScopeDetails -ScopeId $TargetScopeId
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '2' {
      $Error.Clear()
      $TargetScopeId = Read-Host -Prompt "`nEnter the IP address (network ID) for the scope"
      Get-DhcpScopeReservation -ScopeId $TargetScopeId
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '3' {
      $Error.Clear()
      $TargetScopeId = Read-Host -Prompt "`nEnter the IP address (network ID) for the scope"
      Get-DhcpScopeStatistics -ScopeId $TargetScopeId
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '4' {
      $Error.Clear()
      $TargetScopeId = Read-Host -Prompt "`nEnter the IP address (network ID) for the scope"
      Get-DhcpScopeLeases -ScopeId $TargetScopeId
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '5' {
      $Error.Clear()
      Get-DhcpScopeSummary
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '6' {
      $Error.Clear()
      Add-DhcpReservation
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '7' { 
      $Error.Clear()
      $TargetIpAddress = Read-Host -Prompt "`nEnter the IP address of the lease to be converted to a reservation"
      Set-DhcpLeaseToReservation -IpAddress $TargetIpAddress
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '8' {
      $Error.Clear()
      $TargetIpAddress = Read-Host -Prompt "`nEnter the IP address of the reservation to be deleted"
      Remove-DhcpReservation -IpAddress $TargetIpAddress
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '9' {
      $Error.Clear()
      $TargetIpAddress = Read-Host -Prompt "`nEnter the IP address of the lease to be deleted"
      Remove-DhcpLease -IpAddress $TargetIpAddress
      if ($Error.Count -gt 0) { Show-DhcpMainMenu }
    }
    '10' { 
      Remove-PSSession $Script:Session
      return 
    }
    default {
      Write-Host "Incorrect value selected." -ForegroundColor Yellow
    }
  }
}

function Get-DhcpScopeDetails {
  param (
    [Parameter(Mandatory = $true)]
    [IPAddress] $ScopeId
  )
 
  try {
    Get-DhcpServerv4Scope -ScopeId $ScopeId -ErrorAction Stop | Select-Object -Property IPAddress,ScopeId,AddressState,ClientId,Description,Name,Type
    Select-MenuReturnOption
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Get-DhcpScopeReservation {
  param (
    [Parameter(Mandatory = $true)]
    [IPAddress] $ScopeId
  )
 
  try {
    Get-DhcpServerv4Reservation -ScopeId $ScopeId -ErrorAction Stop | Select-Object -Property IPAddress,ScopeId,AddressState,ClientId,Description
    Select-MenuReturnOption
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Get-DhcpScopeStatistics {
  param (
    [Parameter(Mandatory = $true)]
    [IPAddress] $ScopeId
  )
 
  try {
    Get-DhcpServerv4ScopeStatistics -ScopeId $ScopeId -ErrorAction Stop | Select-Object -Property ScopeId,Free,InUse,Reserved,Pending,AddressesFree,PercentageInUse,ReservedAddressSuperscopeName
    Select-MenuReturnOption
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Get-DhcpScopeLeases {
  param (
    [Parameter(Mandatory = $true)]
    [IPAddress] $ScopeId
  )
 
  try {
    Get-DhcpServerv4Lease -ScopeId $ScopeId -ErrorAction Stop | Select-Object -Property HostName,IPAddress,AddressState,ClientId,ClientType,Description,DnsRegistration,DnsRR
    Select-MenuReturnOption
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Get-DhcpScopeSummary { 
  try {
    Get-DhcpServerv4Scope -ErrorAction Stop | Select-Object -Property ScopeId,Name,SubnetMask,StartRange,EndRange,LeaseDuration,State
    Select-MenuReturnOption
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Add-DhcpReservation {
  $IncorrectFormat = $false
  do { 
    if ($IncorrectFormat -eq $true) {
      Write-Host "`nMac address incorrectly formatted: $ReservationMac`n" -ForegroundColor Yellow
    }
    $ReservationMac = Read-Host -Prompt "`nEnter the MAC address in the format XX-XX-XX-XX-XX-XX"
    $IncorrectFormat = $true
  } while ($ReservationMac -notmatch "^([0-9a-fA-F][0-9a-fA-F]-){5}([0-9a-fA-F][0-9a-fA-F])$")
  
  $ReservationScopeId = Read-Host -Prompt "`nEnter the IP address (network ID) for the scope"
  
  # Check if Mac already in use.
  try {
    $ExistingReservation = Get-DhcpServerv4Lease -ScopeId $ReservationScopeId -ClientId $ReservationMac -ErrorAction Stop
    if ($null -ne $ExistingReservation.ClientId) {
      Write-Host "`nThe Mac address: $($ExistingReservation.ClientId) already exists. Please verify the Mac address and try again." -ForegroundColor Yellow
      Add-DhcpReservation
    }
  }
  catch {
    # Mac address does not exist which throws an error on the Get-DhcpServerv4Lease cmdlet.
  }
  
  try {
    do { 
      Clear-Variable IpCheck
      $ReservationIPAddress = Read-Host -Prompt "`nEnter the IP address for the reservation"
      $IpCheck = Get-DhcpServerv4FreeIPAddress -ScopeId $ReservationScopeId -StartAddress $ReservationIPAddress -EndAddress $ReservationIPAddress
      if ($null -eq $IpCheck) {
        Write-Host "$ReservationIPAddress is already in use. Select a different IP address." -ForegroundColor Yellow
      }
    } while ($null -eq $IpCheck)
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
  
  $ReservationDescription = Read-Host -Prompt "`nEnter a description for the reservation (leave blank and press [ENTER] for none)"
  
  try {
    if ($ReservationDescription.Length -gt 0) { 
      Add-DhcpServerv4Reservation -ScopeId $ReservationScopeId -IPAddress $ReservationIPAddress -Description $ReservationDescription
      Select-MenuReturnOption
    }
    else {
      Add-DhcpServerv4Reservation -ScopeId $ReservationScopeId -IPAddress $ReservationIPAddress
      Select-MenuReturnOption
    }
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Set-DhcpLeaseToReservation {
  param (
    [Parameter(Mandatory = $true)]
    [IPAddress] $IpAddress
  )
  
  try {
    Get-DhcpServerv4Lease -IPAddress $IpAddress -ErrorAction Stop | Add-DhcpServerv4Reservation
    Select-MenuReturnOption
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Write-Host "`n`tCheck to see if reservation already exists." -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Remove-DhcpReservation {
  param (
    [Parameter(Mandatory = $true)]
    [IPAddress] $IpAddress
  )
  
  try {
    Remove-DhcpServerv4Reservation -IPAddress $IpAddress -ErrorAction Stop
    Select-MenuReturnOption
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Remove-DhcpLease {
  param (
    [Parameter(Mandatory = $true)]
    [IPAddress] $IpAddress
  )
  
  try {
    Remove-DhcpServerv4Lease -IPAddress $IpAddress -ErrorAction Stop
    Select-MenuReturnOption
  }
  catch {
    Write-Host "`t$_.Exception" -ForegroundColor Red -BackgroundColor Black
    Read-Host -Prompt "Press [ENTER] to continue"
  }
}

function Select-MenuReturnOption {
  $MenuReturnBadChoice = $false
  do {
    $MainMenu = @"

  1 - Return to main menu
  2 - Quit

  Selection
"@    
    if ($MenuReturnBadChoice -eq $true) {
      Clear-Host
      Write-Host "`nInvalid selection: $MenuReturnSelection`n" -ForegroundColor Yellow
    }
    $MenuReturnSelection = Read-Host -Prompt $MainMenu
    $MenuReturnBadChoice = $true
  } while ($MenuReturnSelection -notmatch "^[1-2]$")
  
  switch ($MenuReturnSelection) {
    '1' {
      $Error.Clear()
      Show-DhcpMainMenu
      if ($Error.Count -gt 0) { Select-MenuReturnOption }
    }
    '2' {
      $Error.Clear()
      Remove-PSSession $Script:Session
      return
    }
    default {
      Write-Host "Incorrect value selected." -ForegroundColor Yellow
    }
  }
}

Select-DhcpDhcpServer

if (-not $Script:ExitScript) { 
  Show-DhcpMainMenu
}