Get-GPOsSoM.ps1

<#

Author: I.C.A. Strachan
Version: 1.0
Version History: Based on Ashley McGlone's Get-GPOReport. Here's a shortlink to it: http://tinyurl.com/ofpfnf4

Purpose: Get all GPOs that are linked to Domain, Sites and/or OUs

#>

Function Get-GPOsSoM {

   BEGIN{

      Import-Module GroupPolicy -Verbose:$false
      Import-Module ActiveDirectory -Verbose:$false

      #region Get a list of all GPOs
      $GPOs = Get-GPO -All | 
         Select-Object ID, Path, DisplayName, GPOStatus, WMIFilter
      #endregion

      #Array for GPLinks results
      $gPLinks = @()

      #region GPO Linked to the Domain
      $domainGPO = @{
         Identity   = ((Get-ADDomain).distinguishedName)
         Properties = @('name', 'distinguishedName', 'gPLink', 'gPOptions', 'canonicalname')
      }

      $gPlinks += Get-ADObject @domainGPO | 
         Select-Object 'name', 'distinguishedName', 'gPLink', 'gPOptions', 'canonicalname', 
            @{name='Depth';expression={0}}
      #endregion

      #region GPO Linked to OUs
      $ouGPOs = @{
         Filter     = '*'
         Properties = @('name', 'distinguishedName', 'gPLink', 'gPOptions', 'canonicalname')
      }

      $gPLinks += Get-ADOrganizationalUnit @ouGPOs |
         Select-Object name, distinguishedName, gPLink, gPOptions ,canonicalname ,  
            @{name='Depth';expression={($_.distinguishedName -split 'OU=').count - 1}}
      #endregion

      #region GPOs linked to sites
      $siteGPOs = @{
         LDAPFilter  = '(objectClass=site)' 
         SearchBase  = "CN=Sites,$((Get-ADRootDSE).configurationNamingContext)" 
         SearchScope = 'Onelevel' 
         Properties  = @('name', 'distinguishedName', 'gPLink', 'gPOptions', 'canonicalname')
      }

      $gPLinks += Get-ADObject @siteGPOs |
         Select-Object name, distinguishedName, gPLink, gPOptions ,canonicalname, 
            @{name='Depth';expression={0}}

      #Hashtable to lookup GPOs
      $lookupGPO = $GPOs | Group-Object -AsHashTable -Property 'Path'   
   }

   PROCESS{
      #Get the Scope of Management of each gPLink
      ForEach ($SOM in $gPLinks) {
   
         if ($SOM.gPLink) {

            If ($SOM.gPLink.length -gt 1) {

               $links = @($SOM.gPLink -split {$_ -eq '[' -or $_ -eq ']'} | Where-Object {$_})
               For ( $i = $links.count - 1 ; $i -ge 0 ; $i-- ) {
                  
                  $GPOData = $links[$i] -split {$_ -eq '/' -or $_ -eq ';'}

                  [PSCustomObject]@{
                     Depth             = $SOM.Depth;
                     Name              = $SOM.Name;
                     DistinguishedName = $SOM.distinguishedName;
                     canonicalName     = $SOM.canonicalname;
                     PolicyDN          = $GPOData[2];
                     LinkOrderNr       = $links.count - $i
                     GUID              = $lookupGPO.$($GPOData[2]).ID;
                     DisplayName       = $lookupGPO.$($GPOData[2]).DisplayName;
                     GPOStatus         = $lookupGPO.$($GPOData[2]).GPOStatus;
                     WMIFilter         = $lookupGPO.$($GPOData[2]).WMIFilter.Name;
                     Config            = $GPOData[3];
                     LinkEnabled       = [bool](!([int]$GPOData[3] -band 1));
                     Enforced          = [bool]([int]$GPOData[3] -band 2);
                     BlockInheritance  = [bool]($SOM.gPOptions -band 1)
                  }
               }
            }
         }
      }   
   }

   END{}
}