#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : Remote Desktop Gateway refuses connections -- event 4, 23003 and 23005
    Fix   : Fix the connection authorisation policy
    Source: https://jbtecwiz.com/support/srv-app-rdgateway

    Run as     : Elevated PowerShell on the gateway
    Expect     : 30 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    Event 23003.

    HOW TO UNDO IT
    Remove the added group from the policy.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 5"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  Remote Desktop Gateway refuses connections -- event 4, 23003 and 23005' -ForegroundColor White
Write-Host '  Fix the connection authorisation policy' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   30 minutes'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'Read the event -- it names the user and the policy that rejected them.' -Command {
    Get-WinEvent -LogName 'Microsoft-Windows-TerminalServices-Gateway/Operational' -MaxEvents 40 | Format-Table TimeCreated,Id,Message -Wrap
}

Invoke-Step -Number 2 -Do 'List the connection policies and their groups.' -Command {
    Import-Module RemoteDesktopServices
    Get-ChildItem RDS:\GatewayServer\CAP | Format-Table Name
    Get-ChildItem 'RDS:\GatewayServer\CAP\Default CAP\UserGroups'
}

Invoke-Step -Number 3 -Do 'Add the required group. Groups must be specified in DOMAIN\Group form.' -Command {
    New-Item -Path 'RDS:\GatewayServer\CAP\Default CAP\UserGroups' -Name 'EXAMPLE\RemoteUsers' -ItemType String
}

Invoke-Step -Number 4 -Do 'Check the device redirection and authentication method settings match what the client is offering -- a policy requiring smart cards rejects a password logon here.' -Why 'The gateway evaluates the authentication method before anything else. A mismatch produces a rejection that reads as a credential failure, and the user will keep retyping a correct password.' -Command {
    Get-ChildItem 'RDS:\GatewayServer\CAP\Default CAP' | Format-Table Name,CurrentValue
}

Invoke-Step -Number 5 -Do 'Restart the gateway service after policy changes.' -Command {
    Restart-Service TSGateway
}

Write-Rule "  Confirm it worked"
Show-Prose 'The user connects and event 302 (connection authorised) is logged.' 'White'
Write-Host ''
if (-not $DryRun) {
    Get-WinEvent -LogName 'Microsoft-Windows-TerminalServices-Gateway/Operational' -MaxEvents 20 | Where-Object Id -in 300,302 | Format-Table TimeCreated,Id
}

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/srv-app-rdgateway' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Remove the added group from the policy.' 'DarkGray'
Write-Rule