<#
    .SYNOPSIS
    Get-ADHealth.ps1 - Domain Controller Health Check Script.

    .DESCRIPTION
    This script performs a list of common health checks to a specific domain, or the entire forest. The results are then compiled into a colour coded HTML report.

    .OUTPUTS
    The results are currently only output to HTML for email or as an HTML report file, or sent as an SMTP message with an HTML body.

    .PARAMETER DomainName
    Perform a health check on a specific Active Directory domain.

    .PARAMETER ReportFile
    Output the report details to a file in the current directory.

    .PARAMETER SendEmail
    Send the report via email. You have to configure the correct SMTP settings.

    .EXAMPLE
    .\Get-ADHealth.ps1 -ReportFile
    Checks all domains and all domain controllers in your current forest and creates a report.

    .EXAMPLE
    .\Get-ADHealth.ps1 -DomainName alitajran.com -ReportFile
    Checks all the domain controllers in the specified domain "alitajran.com" and creates a report.

    .EXAMPLE
    .\Get-ADHealth.ps1 -DomainName alitajran.com -SendEmail
    Checks all the domain controllers in the specified domain "alitajran.com" and sends the resulting report as an email message.

    .LINK
    alitajran.com/active-directory-health-check-powershell-script

    .NOTES
    Written by: ALI TAJRAN
    Website:    alitajran.com
    LinkedIn:   linkedin.com/in/alitajran

    .CHANGELOG
    V1.00, 01/21/2023 - Initial version
    V1.10, 06/18/2023 - Added SMTP port to $smpsettings hashtable and date/time to $reportfilename
#>

[CmdletBinding()]
Param(
    [Parameter( Mandatory = $false)]
    [string]$DomainName,

    [Parameter( Mandatory = $false)]
    [switch]$ReportFile,
        
    [Parameter( Mandatory = $false)]
    [switch]$SendEmail
)

#...................................
# Global Variables
#...................................

$now = Get-Date
$date = $now.ToShortDateString()
[array]$allDomainControllers = @()
$reportime = Get-Date
$reportemailsubject = "Domain Controller Health Report"

$smtpsettings = @{
    To         = 'email@domain.com'
    From       = 'adhealth@yourdomain.com'
    Subject    = "$reportemailsubject - $now"
    SmtpServer = "mail.domain.com"
    Port       = "25"
}

#...................................
# Functions
#...................................

# This function gets all the domains in the forest.
Function Get-AllDomains() {
    Write-Verbose "..running function Get-AllDomains"
    $allDomains = (Get-ADForest).Domains 
    return $allDomains
}

# This function gets all the domain controllers in a specified domain.
Function Get-AllDomainControllers ($DomainNameInput) {
    Write-Verbose "..running function Get-AllDomainControllers" 
    [array]$allDomainControllers = Get-ADDomainController -Filter * -Server $DomainNameInput
    return $allDomainControllers
}

# This function tests the name against DNS.
Function Get-DomainControllerNSLookup($DomainNameInput) {
    Write-Verbose "..running function Get-DomainControllerNSLookup" 
    try {
        $domainControllerNSLookupResult = Resolve-DnsName $DomainNameInput -Type A | select -ExpandProperty IPAddress

        $domainControllerNSLookupResult = 'Success'
    }
    catch {
        $domainControllerNSLookupResult = 'Fail'
    }
    return $domainControllerNSLookupResult
}

# This function tests the connectivity to the domain controller.
Function Get-DomainControllerPingStatus($DomainNameInput) {
    Write-Verbose "..running function Get-DomainControllerPingStatus" 
    If ((Test-Connection $DomainNameInput -Count 1 -quiet) -eq $True) {
        $domainControllerPingStatus = "Success"
    }

    Else {
        $domainControllerPingStatus = 'Fail'
    }
    return $domainControllerPingStatus
}

# This function tests the domain controller uptime.
Function Get-DomainControllerUpTime($DomainNameInput) {
    Write-Verbose "..running function Get-DomainControllerUpTime" 

    If ((Test-Connection $DomainNameInput -Count 1 -quiet) -eq $True) {
        try {
            $W32OS = Get-WmiObject -Class Win32_OperatingSystem -ComputerName $DomainNameInput -ErrorAction SilentlyContinue
            $timespan = $W32OS.ConvertToDateTime($W32OS.LocalDateTime) - $W32OS.ConvertToDateTime($W32OS.LastBootUpTime)
            [int]$uptime = "{0:00}" -f $timespan.TotalHours
        }
        catch [exception] {
            $uptime = 'WMI Failure'
        }

    }

    Else {
        $uptime = '0'
    }
    return $uptime  
}

# This function checks the DIT file drive space.
Function Get-DITFileDriveSpace($DomainNameInput) {
    Write-Verbose "..running function Get-DITFileDriveSpace" 

    If ((Test-Connection $DomainNameInput -Count 1 -quiet) -eq $True) {
        try {
            $key = "SYSTEM\CurrentControlSet\Services\NTDS\Parameters"
            $valuename = "DSA Database file"
            $reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine', $DomainNameInput)
            $regkey = $reg.opensubkey($key)
            $NTDSPath = $regkey.getvalue($valuename)
            $NTDSPathDrive = $NTDSPath.ToString().Substring(0, 2)
            $NTDSPathFilter = '"' + 'DeviceID=' + "'" + $NTDSPathDrive + "'" + '"'
            $NTDSDiskDrive = Get-WmiObject -Class Win32_LogicalDisk -ComputerName $DomainNameInput -ErrorAction SilentlyContinue | ? { $_.DeviceID -eq $NTDSPathDrive }
            $NTDSPercentFree = [math]::Round($NTDSDiskDrive.FreeSpace / $NTDSDiskDrive.Size * 100)
        }
        catch [exception] {
            $NTDSPercentFree = 'WMI Failure'
        }
    }

    Else {
        $NTDSPercentFree = '0'
    }
    return $NTDSPercentFree 
}

# This function checks the DNS, NTDS and Netlogon services.
Function Get-DomainControllerServices($DomainNameInput) {
    Write-Verbose "..running function DomainControllerServices"
    $thisDomainControllerServicesTestResult = New-Object PSObject
    $thisDomainControllerServicesTestResult | Add-Member NoteProperty -name DNSService -Value $null
    $thisDomainControllerServicesTestResult | Add-Member NoteProperty -name NTDSService -Value $null
    $thisDomainControllerServicesTestResult | Add-Member NoteProperty -name NETLOGONService -Value $null

    If ((Test-Connection $DomainNameInput -Count 1 -quiet) -eq $True) {
        If ((Get-Service -ComputerName $DomainNameInput -Name DNS -ErrorAction SilentlyContinue).Status -eq 'Running') {
            $thisDomainControllerServicesTestResult.DNSService = 'Success'
        }
        Else {
            $thisDomainControllerServicesTestResult.DNSService = 'Fail'
        }
        If ((Get-Service -ComputerName $DomainNameInput -Name NTDS -ErrorAction SilentlyContinue).Status -eq 'Running') {
            $thisDomainControllerServicesTestResult.NTDSService = 'Success'
        }
        Else {
            $thisDomainControllerServicesTestResult.NTDSService = 'Fail'
        }
        If ((Get-Service -ComputerName $DomainNameInput -Name netlogon -ErrorAction SilentlyContinue).Status -eq 'Running') {
            $thisDomainControllerServicesTestResult.NETLOGONService = 'Success'
        }
        Else {
            $thisDomainControllerServicesTestResult.NETLOGONService = 'Fail'
        }
    }

    Else {
        $thisDomainControllerServicesTestResult.DNSService = 'Fail'
        $thisDomainControllerServicesTestResult.NTDSService = 'Fail'
        $thisDomainControllerServicesTestResult.NETLOGONService = 'Fail'
    }
    return $thisDomainControllerServicesTestResult
} 

# This function runs the five DCDiag tests and saves them in a variable for later processing.
Function Get-DomainControllerDCDiagTestResults($DomainNameInput) {
    Write-Verbose "..running function Get-DomainControllerDCDiagTestResults"

    $DCDiagTestResults = New-Object Object
    If ((Test-Connection $DomainNameInput -Count 1 -quiet) -eq $True) {

        $DCDiagTest = (Dcdiag.exe /s:$DomainNameInput /test:services /test:FSMOCheck /test:KnowsOfRoleHolders /test:Advertising /test:Replications) -split ('[\r\n]')

        $DCDiagTestResults | Add-Member -Type NoteProperty -Name "ServerName" -Value $DomainNameInput
        $DCDiagTest | % {
            Switch -RegEx ($_) {
                "Starting" { $TestName = ($_ -Replace ".*Starting test: ").Trim() }
                "passed test|failed test" {
                    If ($_ -Match "passed test") {
                        $TestStatus = "Passed"
                        # $TestName
                        # $_
                    }
                    Else {
                        $TestStatus = "Failed"
                        # $TestName
                        # $_
                    }
                }
            } 
            If ($TestName -ne $Null -And $TestStatus -ne $Null) {
                $DCDiagTestResults | Add-Member -Name $("$TestName".Trim()) -Value $TestStatus -Type NoteProperty -force
                $TestName = $Null; $TestStatus = $Null
            }
        }
        return $DCDiagTestResults
    }

    Else {
        $DCDiagTestResults | Add-Member -Type NoteProperty -Name "ServerName" -Value $DomainNameInput
        $DCDiagTestResults | Add-Member -Name Replications -Value 'Failed' -Type NoteProperty -force 
        $DCDiagTestResults | Add-Member -Name Advertising -Value 'Failed' -Type NoteProperty -force 
        $DCDiagTestResults | Add-Member -Name KnowsOfRoleHolders -Value 'Failed' -Type NoteProperty -force
        $DCDiagTestResults | Add-Member -Name FSMOCheck -Value 'Failed' -Type NoteProperty -force
        $DCDiagTestResults | Add-Member -Name Services -Value 'Failed' -Type NoteProperty -force 
    }
    return $DCDiagTestResults
}

# This function checks the server OS version.
Function Get-DomainControllerOSVersion ($DomainNameInput) {
    Write-Verbose "..running function Get-DomainControllerOSVersion"
    $W32OSVersion = (Get-WmiObject -Class Win32_OperatingSystem -ComputerName $DomainNameInput -ErrorAction SilentlyContinue).Caption
    return $W32OSVersion
}

# This function checks the free space on the OS drive
Function Get-DomainControllerOSDriveFreeSpace ($DomainNameInput) {
    Write-Verbose "..running function Get-DomainControllerOSDriveFreeSpace"

    If ((Test-Connection $DomainNameInput -Count 1 -quiet) -eq $True) {
        try {
            $thisOSDriveLetter = (Get-WmiObject Win32_OperatingSystem -ComputerName $DomainNameInput -ErrorAction SilentlyContinue).SystemDrive
            $thisOSPathFilter = '"' + 'DeviceID=' + "'" + $thisOSDriveLetter + "'" + '"'
            $thisOSDiskDrive = Get-WmiObject -Class Win32_LogicalDisk -ComputerName $DomainNameInput -ErrorAction SilentlyContinue | ? { $_.DeviceID -eq $thisOSDriveLetter }
            $thisOSPercentFree = [math]::Round($thisOSDiskDrive.FreeSpace / $thisOSDiskDrive.Size * 100)
        }

        catch [exception] {
            $thisOSPercentFree = 'WMI Failure'
        }
    }
    return $thisOSPercentFree
}

# This function generates HTML code from the results of the above functions.
Function New-ServerHealthHTMLTableCell() {
    param( $lineitem )
    $htmltablecell = $null

    switch ($($reportline."$lineitem")) {
        $success { $htmltablecell = "<td class=""pass"">$($reportline."$lineitem")</td>" }
        "Success" { $htmltablecell = "<td class=""pass"">$($reportline."$lineitem")</td>" }
        "Passed" { $htmltablecell = "<td class=""pass"">$($reportline."$lineitem")</td>" }
        "Pass" { $htmltablecell = "<td class=""pass"">$($reportline."$lineitem")</td>" }
        "Warn" { $htmltablecell = "<td class=""warn"">$($reportline."$lineitem")</td>" }
        "Access Denied" { $htmltablecell = "<td class=""warn"">$($reportline."$lineitem")</td>" }
        "Fail" { $htmltablecell = "<td class=""fail"">$($reportline."$lineitem")</td>" }
        "Failed" { $htmltablecell = "<td class=""fail"">$($reportline."$lineitem")</td>" }
        "Could not test server uptime." { $htmltablecell = "<td class=""fail"">$($reportline."$lineitem")</td>" }
        "Could not test service health. " { $htmltablecell = "<td class=""warn"">$($reportline."$lineitem")</td>" }
        "Unknown" { $htmltablecell = "<td class=""warn"">$($reportline."$lineitem")</td>" }
        default { $htmltablecell = "<td>$($reportline."$lineitem")</td>" }
    }
    return $htmltablecell
}

if (!($DomainName)) {
    Write-Host "..no domain specified, using all domains in forest" -ForegroundColor Yellow
    $allDomains = Get-AllDomains
    $reportFileName = 'forest_health_report_' + (Get-ADForest).name + '_' + (Get-Date -Format "yyyyMMdd_HHmmss") + '.html'
}

Else {
    Write-Host "..domain name specified on cmdline"
    $allDomains = $DomainName
    $reportFileName = 'dc_health_report_' + $DomainName + '_' + (Get-Date -Format "yyyyMMdd_HHmmss") + '.html'
}

foreach ($domain in $allDomains) {
    Write-Host "..testing domain" $domain -ForegroundColor Green
    [array]$allDomainControllers = Get-AllDomainControllers $domain
    $totalDCtoProcessCounter = $allDomainControllers.Count
    $totalDCProcessCount = $allDomainControllers.Count 

    foreach ($domainController in $allDomainControllers) {
        $stopWatch = [system.diagnostics.stopwatch]::StartNew()
        Write-Host "..testing domain controller" "(${totalDCtoProcessCounter} of ${totalDCProcessCount})" $domainController.HostName -ForegroundColor Cyan 
        $DCDiagTestResults = Get-DomainControllerDCDiagTestResults $domainController.HostName
        $thisDomainController = New-Object PSObject
        $thisDomainController | Add-Member NoteProperty -name Server -Value $null
        $thisDomainController | Add-Member NoteProperty -name Site -Value $null
        $thisDomainController | Add-Member NoteProperty -name "OS Version" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "Operation Master Roles" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "DNS" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "Ping" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "Uptime (hrs)" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "DIT Free Space (%)" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "OS Free Space (%)" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "DNS Service" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "NTDS Service" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "NetLogon Service" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "DCDIAG: Advertising" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "DCDIAG: Replications" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "DCDIAG: FSMO KnowsOfRoleHolders" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "DCDIAG: FSMO Check" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "DCDIAG: Services" -Value $null
        $thisDomainController | Add-Member NoteProperty -name "Processing Time" -Value $null
        $OFS = "`r`n"
        $thisDomainController.Server = ($domainController.HostName).ToLower()
        $thisDomainController.Site = $domainController.Site
        $thisDomainController."OS Version" = (Get-DomainControllerOSVersion $domainController.hostname)
        $thisDomainController."Operation Master Roles" = $domainController.OperationMasterRoles
        $thisDomainController.DNS = Get-DomainControllerNSLookup $domainController.HostName
        $thisDomainController.Ping = Get-DomainControllerPingStatus $domainController.HostName
        $thisDomainController."Uptime (hrs)" = Get-DomainControllerUpTime $domainController.HostName
        $thisDomainController."DIT Free Space (%)" = Get-DITFileDriveSpace $domainController.HostName
        $thisDomainController."OS Free Space (%)" = Get-DomainControllerOSDriveFreeSpace $domainController.HostName
        $thisDomainController."DNS Service" = (Get-DomainControllerServices $domainController.HostName).DNSService
        $thisDomainController."NTDS Service" = (Get-DomainControllerServices $domainController.HostName).NTDSService
        $thisDomainController."NetLogon Service" = (Get-DomainControllerServices $domainController.HostName).NETLOGONService
        $thisDomainController."DCDIAG: Replications" = $DCDiagTestResults.Replications
        $thisDomainController."DCDIAG: Advertising" = $DCDiagTestResults.Advertising
        $thisDomainController."DCDIAG: FSMO KnowsOfRoleHolders" = $DCDiagTestResults.KnowsOfRoleHolders
        $thisDomainController."DCDIAG: FSMO Check" = $DCDiagTestResults.FSMOCheck
        $thisDomainController."DCDIAG: Services" = $DCDiagTestResults.Services
        $thisDomainController."Processing Time" = $stopWatch.Elapsed.Seconds
        [array]$allTestedDomainControllers += $thisDomainController
        $totalDCtoProcessCounter -- 
    }

}

# Common HTML head and styles
$htmlhead = "<html>
                <style>
                BODY{font-family: Arial; font-size: 8pt;}
                H1{font-size: 16px;}
                H2{font-size: 14px;}
                H3{font-size: 12px;}
                TABLE{border: 1px solid black; border-collapse: collapse; font-size: 8pt;}
                TH{border: 1px solid black; background: #dddddd; padding: 5px; color: #000000;}
                TD{border: 1px solid black; padding: 5px; }
                td.pass{background: #7FFF00;}
                td.warn{background: #FFE600;}
                td.fail{background: #FF0000; color: #ffffff;}
                td.info{background: #85D4FF;}
                </style>
                <body>
                <h1 align=""left"">Domain Controller Health Check Report</h1>
                <h3 align=""left"">Generated: $reportime</h3>"
                   
# Domain Controller Health Report Table Header
$htmltableheader = "<h3>Domain Controller Health Summary</h3>
                        <h3>Forest: $((Get-ADForest).Name)</h3>
                        <p>
                        <table>
                        <tr>
                        <th>Server</th>
                        <th>Site</th>
                        <th>OS Version</th>
                        <th>Operation Master Roles</th>
                        <th>DNS</th>
                        <th>Ping</th>
                        <th>Uptime (hrs)</th>
                        <th>DIT Free Space (%)</th>
                        <th>OS Free Space (%)</th>
                        <th>DNS Service</th>
                        <th>NTDS Service</th>
                        <th>NetLogon Service</th>
                        <th>DCDIAG: Advertising</th>
                        <th>DCDIAG: Replications</th>
                        <th>DCDIAG: FSMO KnowsOfRoleHolders</th>
                        <th>DCDIAG: FSMO Check</th>
                        <th>DCDIAG: Services</th>
                        <th>Processing Time</th>
                        </tr>"

# Domain Controller Health Report Table
$serverhealthhtmltable = $serverhealthhtmltable + $htmltableheader

# This section will process through the $allTestedDomainControllers array object and create and colour the HTML table based on certain conditions.
foreach ($reportline in $allTestedDomainControllers) {
      
    if (Test-Path variable:fsmoRoleHTML) {
        Remove-Variable fsmoRoleHTML
    }

    if (($reportline."Operation Master Roles") -gt 0) {
        foreach ($line in $reportline."Operation Master Roles") {
            if ($line.count -gt 0) {
                [array]$fsmoRoleHTML += $line.ToString() + '<br>'
            }
        }
    }

    else {
        $fsmoRoleHTML += 'None<br>'
    }

    $htmltablerow = "<tr>"
    $htmltablerow += "<td>$($reportline.server)</td>"
    $htmltablerow += "<td>$($reportline.site)</td>"
    $htmltablerow += "<td>$($reportline."OS Version")</td>"
    $htmltablerow += "<td>$($fsmoRoleHTML)</td>"
    $htmltablerow += (New-ServerHealthHTMLTableCell "DNS" )                  
    $htmltablerow += (New-ServerHealthHTMLTableCell "Ping")

    if ($($reportline."uptime (hrs)") -eq "WMI Failure") {
        $htmltablerow += "<td class=""warn"">Could not test server uptime.</td>"        
    }
    elseif ($($reportline."Uptime (hrs)") -eq $string17) {
        $htmltablerow += "<td class=""warn"">$string17</td>"
    }
    else {
        $hours = [int]$($reportline."Uptime (hrs)")
        if ($hours -le 24) {
            $htmltablerow += "<td class=""warn"">$hours</td>"
        }
        else {
            $htmltablerow += "<td class=""pass"">$hours</td>"
        }
    }

    $space = $reportline."DIT Free Space (%)"
        
    if ($space -eq "WMI Failure") {
        $htmltablerow += "<td class=""warn"">Could not test server free space.</td>"        
    }
    elseif ($space -le 30) {
        $htmltablerow += "<td class=""warn"">$space</td>"
    }
    else {
        $htmltablerow += "<td class=""pass"">$space</td>"
    }

    $osSpace = $reportline."OS Free Space (%)"
        
    if ($osSpace -eq "WMI Failure") {
        $htmltablerow += "<td class=""warn"">Could not test server free space.</td>"        
    }
    elseif ($osSpace -le 30) {
        $htmltablerow += "<td class=""warn"">$osSpace</td>"
    }
    else {
        $htmltablerow += "<td class=""pass"">$osSpace</td>"
    }

    $htmltablerow += (New-ServerHealthHTMLTableCell "DNS Service")
    $htmltablerow += (New-ServerHealthHTMLTableCell "NTDS Service")
    $htmltablerow += (New-ServerHealthHTMLTableCell "NetLogon Service")
    $htmltablerow += (New-ServerHealthHTMLTableCell "DCDIAG: Advertising")
    $htmltablerow += (New-ServerHealthHTMLTableCell "DCDIAG: Replications")
    $htmltablerow += (New-ServerHealthHTMLTableCell "DCDIAG: FSMO KnowsOfRoleHolders")
    $htmltablerow += (New-ServerHealthHTMLTableCell "DCDIAG: FSMO Check")
    $htmltablerow += (New-ServerHealthHTMLTableCell "DCDIAG: Services")
          
    $averageProcessingTime = ($allTestedDomainControllers | measure -Property "Processing Time" -Average).Average
    if ($($reportline."Processing Time") -gt $averageProcessingTime) {
        $htmltablerow += "<td class=""warn"">$($reportline."Processing Time")</td>"        
    }
    elseif ($($reportline."Processing Time") -le $averageProcessingTime) {
        $htmltablerow += "<td class=""pass"">$($reportline."Processing Time")</td>"
    }

    [array]$serverhealthhtmltable = $serverhealthhtmltable + $htmltablerow
}

$serverhealthhtmltable = $serverhealthhtmltable + "</table></p>"

$htmltail = "* Windows 2003 Domain Controllers do not have the NTDS Service running. Failing this test is normal for that version of Windows.<br>
    * DNS test is performed using Resolve-DnsName. This cmdlet is only available from Windows 2012 onwards.
                </body>
                </html>"

$htmlreport = $htmlhead + $serversummaryhtml + $dagsummaryhtml + $serverhealthhtmltable + $dagreportbody + $htmltail

if ($ReportFile) {
    $htmlreport | Out-File $reportFileName -Encoding UTF8
}

if ($SendEmail) {
    try {
        # Send email message
        Send-MailMessage @smtpsettings -Body $htmlreport -BodyAsHtml -Encoding ([System.Text.Encoding]::UTF8) -ErrorAction Stop
        Write-Host "Email sent successfully." -ForegroundColor Green
    }
    catch {
        Write-Host "Failed to send email. Error: $_" -ForegroundColor Red
    }
}