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Putting Shay's Powershell Registry Functions To Use

Recently I needed to check some registry key values on a bunch of servers. There were far too many servers to make this a manual task and in addition if they weren't what I was expecting then I needed to change them.

Shay Levy has very helpfully published a Stand Alone Registry Functions Library which I made use of. It allows you to query and set registry values for things such as DWords, Strings, Binary Values on remote machines very easily. In my case I was particularly interested in some configuration settings for the ICA protocol, HKLM\System\CurrentControlSet\Control\Terminal Server\WinStations\ICA-tcp, all of them DWords.

First of all we use Shay's Get-RegDWord function at the top of the script which contains some .NET code to query a remote registry

function Get-RegDWord{
param(
  [string]$server = ".",
  [string]$hive,
  [string]$keyName,
  [string]$valueName,
  [object]$defaultValue="Your default value"
)

$hives = [enum]::getnames([Microsoft.Win32.RegistryHive])

if($hives -notcontains $hive){
  write-error "Invalid hive value";
  return;
}
$regHive = [Microsoft.Win32.RegistryHive]$hive;
$regKey = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey($regHive,$server);
$subKey = $regKey.OpenSubKey($keyName);

if(!$subKey){
  write-error "The specified registry key does not exist.";
  return;
}
$subKey.GetValue($valueName,$defaultValue);
} 

Then we specify the list of servers to query. You could either use something like:

$servers = Get-Content servers.txt

or in my case they were all virtual servers in VMware so I used a couple of VI Toolkit commands to specify the list

# Connect to Virtual Center
Connect-VIServer  vc

# Get a list of all the powered on APP servers
$servers = Get-Folder 'Servers' | Get-VM | Where-Object {$_.Powerstate -eq 'PoweredOn'}

Then we loop through each server, call Shay's Get-RegDWord function for each of the DWords we are interested in and store the results in the $myCOl variable. At the end we export the $myCol variable into a CSV file for handy viewing.

# Create an empty array to store the results in
$myCol = @()

foreach ($server in $servers){

 $hive = 'LocalMachine'
 $keyname = 'System\CurrentControlSet\Control\Terminal Server\WinStations\ICA-tcp'

 # Find MaxIdleTime
    $valuename = 'MaxIdleTime'
 $MaxIdleTime = Get-RegDWord $server $hive $keyName $valueName

 # Find fInheritMaxIdleTime
    $valueName = 'fInheritMaxIdleTime'
 $fInheritMaxIdleTime = Get-RegDWord $server $hive $keyName $valueName

 # Find MaxDisconnectionTime
    $valueName = 'MaxDisconnectionTime'
 $MaxDisconnectionTime = Get-RegDWord $server $hive $keyName $valueName

 # Find fInheritMaxDisconnectionTime
    $valueName = 'fInheritMaxDisconnectionTime'
 $fInheritMaxDisconnectionTime = Get-RegDWord $server $hive $keyName $valueName

 # Add the results to the $MYInfo variable, then $myCol
    $MYInfo = "" | select-Object Name,MaxIdleTime,fInheritMaxIdleTime,MaxDisconnectionTime,fInheritMaxDisconnectionTime
 $MYInfo.Name = $server
 $MYInfo.MaxIdleTime = $MaxIdleTime
 $MYInfo.fInheritMaxIdleTime = $fInheritMaxIdleTime
 $MYInfo.MaxDisconnectionTime = $MaxDisconnectionTime
 $MYInfo.fInheritMaxDisconnectionTime = $fInheritMaxDisconnectionTime
 $myCol += $MYInfo

}

# Export the results to a csv file
$myCol | Export-Csv citrixservers.csv -NoTypeInformation

Now that we can view the results I was able to see that I needed to set a lot of these values to something new. Using Shay's Set-RegDWord function it is a pretty straightfoward task to extend the above to do that. First of all add the function to the top of the script.

function Set-RegDWord{
  param(
      [string]$server = ".",
      [string]$hive,
      [string]$keyName,
      [string]$valueName,
      [double]$value  
  )

  $hives = [enum]::getnames([Microsoft.Win32.RegistryHive])

  if($hives -notcontains $hive){
      write-error "Invalid hive value";
      return;
  }
  $regHive = [Microsoft.Win32.RegistryHive]$hive;
  $regKey = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey($regHive,$server);
  $subKey = $regKey.OpenSubKey($keyName,$true);

  if(!$subKey){
      write-error "The specified registry key does not exist.";
      return;
  }
  $subKey.SetValue($valueName, $value,[Microsoft.Win32.RegistryValueKind]::DWord);
  if($?) {$true} else {$false}
} 

Then for each of the values you want to change use an if statement to check whether it needs changing and if so call Shay's Set-RegDword to make the necessary changes.

    # Find fInheritMaxIdleTime
    $valueName = 'fInheritMaxIdleTime'
   $fInheritMaxIdleTime = Get-RegDWord $server $hive $keyName $valueName

   # Check the value and change if necessary
    if ($fInheritMaxIdleTime -eq 1){

   $value = '0'
   Set-RegDWord $server $hive $keyName $valueName $value

   }

Thanks again to Shay for publishing these functions, it made this particular task very easy to complete and I'm sure I'll be using them again in the future.