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

    Fault : 802.1X or VPN authentication fails at NPS -- reason codes 16, 23, 48 and 265
    Fix   : Fix the certificate chain
    Source: https://jbtecwiz.com/support/srv-app-nps-radius

    Run as     : Elevated PowerShell on the NPS server
    Expect     : 40 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    Reason code 265.

    HOW TO UNDO IT
    The previous certificate can be reselected in the policy if it has not
    expired.

    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 6"
    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 '  802.1X or VPN authentication fails at NPS -- reason codes 16, 23, 48 and 265' -ForegroundColor White
Write-Host '  Fix the certificate chain' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   40 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 rejection, which names the certificate problem.' -Command {
    Get-WinEvent -LogName Security -MaxEvents 100 | Where-Object Id -eq 6273 | Select-Object -First 3 | Format-List Message
}

Invoke-Step -Number 2 -Do 'Check the server certificate NPS is using -- it needs a Server Authentication EKU and the private key.' -Command {
    Get-ChildItem Cert:\LocalMachine\My | Where-Object { $_.EnhancedKeyUsageList.FriendlyName -contains 'Server Authentication' } | Format-List Subject,NotAfter,Thumbprint,HasPrivateKey
}

Invoke-Step -Number 3 -Do 'The most common cause is an expired certificate that was renewed but not selected in the network policy. Renewing does not update the policy.' -Why 'The policy stores the certificate by identity. A renewed certificate is a new object, so the policy still points at the old one and every authentication fails on the day it expires.' -Manual

Invoke-Step -Number 4 -Do 'Open the network policy, edit the PEAP or EAP-TLS configuration, and select the current certificate. Do this on every NPS server.' -Manual

Invoke-Step -Number 5 -Do 'Confirm the clients trust the issuing CA -- if they do not, they reject the server and it presents at the server as this code.' -Command {
    Get-ChildItem Cert:\LocalMachine\Root | Where-Object Subject -like '*YourCA*' | Format-List Subject,NotAfter
}

Invoke-Step -Number 6 -Do 'Check the CRL is reachable from the clients, since a revocation check that cannot complete fails closed by default.' -Command {
    certutil -URL (Get-ChildItem Cert:\LocalMachine\My | Select-Object -First 1).Thumbprint
}

Write-Rule "  Confirm it worked"
Show-Prose 'Event 6272 (access granted) appears and clients authenticate.' 'White'
Write-Host ''
if (-not $DryRun) {
    Get-WinEvent -LogName Security -MaxEvents 50 | Where-Object Id -eq 6272 | Select-Object -First 3 TimeCreated
}

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-nps-radius' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: The previous certificate can be reselected in the policy if it has not expired.' 'DarkGray'
Write-Rule