Powershell script for performing reverse lookups of IP Addresses

ip_lookup.ps1

$stop = $args.Count
$inputIP = ""
$inputFile = ""
$knownIPFile = ""
$showUsage = 0
$verbose = 0
for ($i = 0; $i -lt $stop; $i++)
{
	if ($args[$i] -eq "-f") {
		if ( ($i + 1) -eq $stop) {
			$showUsage = 1
		}
		else {
			$i++
			$inputFile = $args[$i]
		}
	}
	elseif ($args[$i] -eq "-k") {
		if ( ($i + 1) -eq $stop) {
			$showUsage = 1
		}
		else {
			$i++
			$knownIPFile = $args[$i]
		}
	}
	elseif ($args[$i] -eq "-verbose") {
		$verbose = 1
	}
	else {
		if ( ($i + 1) -eq $stop) {
			$inputIP = $args[$i]
		}
		else {
			$showUsage = 1
		}
	}
}

if ($stop -eq 0) {
	$showUsage = 1
}

if ($showUsage) {
	Write-Host "Usage: ip_lookup.ps1 [-multiline] [-k <KNOWN_IP_FILE] -f <FILENAME>"
	Write-Host "       ip_lookup.ps1 [-multiline] [-k <KNOWN_IP_FILE] <IP_ADDRESS>"
	Write-Error "Bad Input"
	exit
}

$knownIPs = @{}
function LoadKnownIPs($knownIPList)
{
	# File should be IP<TAB>Description
	$reader = [System.IO.File]::OpenText($knownIPList)
	$line = $reader.ReadLine()
	
	while( $line) 
	{ 
		$result = $line.Split("`t")
		if ($result.Count -le 2) {
			$knownIPs[$result[0].Trim()] = $result[1]
		}
		else {
			Write-Output ("-" + $result[0].Trim() + "-")
			Write-Output "Error at $line with " + $result.Count
		}
		$line = $reader.ReadLine() 
	}
	$reader.Close()
}

if ( $knownIPFile -ne "" ) {
	LoadKnownIPs($knownIPFile)
}

function LookupIP($ip) {
	$result = nslookup $ip  2> $null | select-string -pattern "Name:"
	if ( ! $result ) { $result = "" }
	$result = $result.ToString()
	if ($result.StartsWith("Name:")) {
		$result = $result.Split()
		$result = $result[$result.Count -1 ]
	}
	else {
		$result = "NOT FOUND"
	}
	$knownMatch = ""
	if ($knownIPs.ContainsKey($ip)) {
		$knownMatch = $knownIPs[$ip]
	}
	if ($verbose) {
		Write-Output $ip 
		Write-Output $result 
		Write-Output $knownMatch
	} 
	else {
		Write-Output "$ip `t $result `t $knownMatch"
	}
}

if ( $inputFile -ne "") {
	$reader = [System.IO.File]::OpenText($inputFile)
	$line = $reader.ReadLine()
	
	while( $line) 
	{ 
		LookupIP $line.Trim()
		$line = $reader.ReadLine() 
	}
	$reader.Close()
}
else {
	LookupIP $inputIP
}

Good morning and thanks for sharing,

just to ask if the script can be used to check if the reverse dns lookup successful yes or no and the ip name showing reverse lookups of IP Addresses and Server (fqdn) for example $result = adress and $result = name