check-internet.ps1

<#
  .SYNOPSIS
    Check internet connection by pinging a list of remote and local servers
#>

# Local gateway recommended
$localServers = @("192.168.1.1")

# Remote servers to ping
$remoteServers = @(
  "8.8.8.8",
  "9.9.9.9",
  "4.2.2.2"
)

$pingIntervalSeconds = 1
$pingTimeoutSeconds = 1

$outputFile = "check-internet-$(Get-Date -Format 'yyyy-MM-dd-HHmm').log"
$outputPath = Join-Path (Get-Location) $outputFile 

function Ping-Servers()
{
  <#
  .SYNOPSIS
    Ping all servers and return $true if any pings are successful
  #>
  param (
    # Array of servers to ping
    [Parameter(
      Mandatory = $true,
      ValueFromPipelineByPropertyName = $true,
      Position = 0
    )]
    $Servers
  )  

  $result = $Servers | ForEach-Object {
    return Test-Connection -TargetName $_ -IPv4 -Quiet -Count 1 -TimeoutSeconds $pingTimeoutSeconds
  }

  return ($result -Contains $true)
}

Write-Host ""
Write-Host "Log output: $outputPath"
Write-Host ""

Write-Output "Starting ping tests for" | Tee-Object -FilePath $outputPath
Write-Output "  Remote servers: $remoteServers" | Tee-Object -FilePath $outputPath -Append
Write-Output "  Local servers: $localServers" | Tee-Object -FilePath $outputPath -Append
Write-Output "" | Tee-Object -FilePath $outputPath -Append

$failing = $false
$failingStartTime = $null

while ($true) {
  $remoteResult = Ping-Servers -Servers $remoteServers
  $localResult = Ping-Servers -Servers $localServers

  if($remoteResult -and (-not $failing)) {
    # Success: Successful remote ping and not currently failing, do nothing
  } elseif((-not $remoteResult) -and (-not $failing)) {
    # Failure starting: Failed remote pings and not currently failing
    $failing = $true
    $failingStartTime = Get-Date
    Write-Output "$($failingStartTime): Failed to ping all remote servers, local ping result: $localResult" | Tee-Object -FilePath $outputPath -Append
  } elseif((-not $remoteResult) -and $failing) {
    # Failure continuing: Failed remote pings and currently failing, do nothing
  } elseif($remoteResult -and $failing) {
    # Failure ending: Successful remote ping and currently failing
    $failing = $false
    $failingEndTime = Get-Date
    $duration = $failingEndTime - $failingStartTime
    Write-Output "$($failingEndTime): Successfully pinged a remote servers, failure duration: $duration, local ping result: $localResult" | Tee-Object -FilePath $outputPath -Append
  }

  Start-Sleep -Seconds $pingIntervalSeconds
}