test-netconnect-1liner.ps1

# Test each port individually against any external host
# note: script will also accept `.\test-netconnect -ComputerName <IPv4_addr>`
# if you choose to execute as if it's just Test-NetConnection
param (
    [Parameter(Mandatory=$true, HelpMessage="Enter the target IPv4 address")]
    [string]$ComputerName = (Read-Host "Please enter the target IPv4 address")
)

# Test each port individually against any external host
Test-NetConnection w3.org -Port 443

# Quick one-liner to test multiple ports against the provided external host
$ports = 8000,8001,8002,22,53,80,443,5000,5001,5002
$ports | ForEach-Object {
    $port = $_;
    if (Test-NetConnection -ComputerName $ComputerName -Port $port -InformationLevel Quiet -WarningAction SilentlyContinue) {
        "Port $port is open"
    } else {
        "Port $port is closed"
    }
}