Windows network troubleshooting commands cheat sheet

ping -l 1200 8.8.8.8

Test-Connection 8.8.8.8 -BufferSize 1200

ping -n 1000 google.com

Test-Connection google.com -Count 1000

ping 8.8.8.8 -t

Test-Connection  8.8.8.8  -Count 10000

Test-Connection  8.8.8.8  -Repeat

for /L %A in (1400,20,2500) do ping -f -l %A -n 2  8.8.8.8

for /L %i in (1,1,254) do @ping -n 1  192.168.3.%i | find "Reply"

<#
.SYNOPSIS
    Ping-sweep a network given in CIDR notation and list only hosts that respond.
.PARAMETER Cidr
    Network in CIDR notation, e.g. 192.168.17.0/24
.PARAMETER TimeoutMs
    Reply timeout per host in milliseconds (default 1000).
.PARAMETER ResolveHostname
    Also perform a reverse-DNS lookup for each responding host (slower).
.EXAMPLE
    .\Ping-Sweep.ps1 192.168.17.0/24
.EXAMPLE
    .\Ping-Sweep.ps1 10.0.0.0/22 -TimeoutMs 500 -ResolveHostname
#>
[CmdletBinding()]
param(
    [Parameter(Mandatory = $true, Position = 0)]
    [string]$Cidr,

    [int]$TimeoutMs = 1000,

    [switch]$ResolveHostname
)

# ---------- Parse the CIDR ----------
if ($Cidr -notmatch '^\d{1,3}(\.\d{1,3}){3}/\d{1,2}$') {
    throw "Invalid CIDR '$Cidr'. Expected format like 192.168.17.0/24"
}

$ipText, $prefixText = $Cidr -split '/'
$prefix = [int]$prefixText
if ($prefix -lt 0 -or $prefix -gt 32) {
    throw "Prefix length must be between 0 and 32 (got $prefix)."
}

$ipBytes = [System.Net.IPAddress]::Parse($ipText).GetAddressBytes()
[Array]::Reverse($ipBytes)
$ipInt = [BitConverter]::ToUInt32($ipBytes, 0)

if ($prefix -eq 0) {
    $mask = [uint32]0
} else {
    $mask = [uint32]::MaxValue -shl (32 - $prefix)
}
$invertedMask = $mask -bxor [uint32]::MaxValue
$network   = $ipInt -band $mask
$broadcast = $network -bor $invertedMask

function ConvertTo-IPAddress([uint32]$Value) {
    $b = [BitConverter]::GetBytes($Value)
    [Array]::Reverse($b)
    return ([System.Net.IPAddress]$b).ToString()
}

# ---------- Build the list of targets ----------
$targets = @()
$hostBits = 32 - $prefix

if ($hostBits -ge 2) {
    for ($i = $network + 1; $i -lt $broadcast; $i++) {
        $targets += ConvertTo-IPAddress $i
    }
} else {
    for ($i = $network; $i -le $broadcast; $i++) {
        $targets += ConvertTo-IPAddress $i
    }
}

Write-Host "Sweeping $Cidr -> $($targets.Count) host(s)..." -ForegroundColor Cyan

# ---------- Concurrent ping sweep ----------
# One Ping object per host: each Ping allows only ONE async call at a time.
$jobs = @()
foreach ($ip in $targets) {
    $pinger = New-Object System.Net.NetworkInformation.Ping
    $jobs += [PSCustomObject]@{
        IP     = $ip
        Pinger = $pinger
        Task   = $pinger.SendPingAsync($ip, $TimeoutMs)
    }
}

$alive = foreach ($job in $jobs) {
    try {
        $null = $job.Task.Wait($TimeoutMs + 500)   # all tasks already run in parallel
        $reply = $job.Task.Result
        if ($reply.Status -eq [System.Net.NetworkInformation.IPStatus]::Success) {
            [PSCustomObject]@{
                IPAddress = $reply.Address.ToString()
                TimeMs    = $reply.RoundtripTime
            }
        }
    } catch {
        # host down / unreachable / timeout
    } finally {
        $job.Pinger.Dispose()
    }
}

# ---------- Optional reverse DNS ----------
if ($ResolveHostname -and $alive) {
    foreach ($host in $alive) {
        try {
            $host | Add-Member -NotePropertyName Hostname `
                -NotePropertyValue ([System.Net.Dns]::GetHostEntry($host.IPAddress).HostName)
        } catch {
            $host | Add-Member -NotePropertyName Hostname -NotePropertyValue '(n/a)'
        }
    }
}

# ---------- Output ----------
if ($alive) {
    Write-Host "`n$($alive.Count) host(s) responded:`n" -ForegroundColor Green
    $alive | Sort-Object IPAddress | Format-Table -AutoSize
} else {
    Write-Host "`nNo hosts responded." -ForegroundColor Yellow
}

nslookup -type=MX yurisk.info 1.1.1.1

Resolve-DnsName yurisk.info  -Type MX -Server 1.1.1.1

nslookup -type=SOA yurisk.info

Resolve-DnsName yurisk.info -Type SOA

ipconfig /displaydns

Get-DnsClientCache

type %SYSTEMROOT%\System32\drivers\etc\hosts

Get-Content "$env:SystemRoot\System32\drivers\etc\hosts"

netsh advfirewall set allprofiles state off

Set-NetFirewallProfile -Profile Domain,Public,Private -Enabled False

netsh advfirewall set allprofiles state off

Set-NetFirewallProfile -Profile Domain,Public,Private -Enabled True

netsh advfirewall firewall show rule name=all dir=in

Get-NetFirewallRule -Direction Inbound | `
Where-Object Enabled -eq "True" | `
Select-Object DisplayName, Action, Direction

netstat -ano | findstr /R /C:"LISTENING"

Get-NetTCPConnection -State Listen | `
Select-Object LocalAddress, LocalPort, OwningProcess