This PowerShell script is useful for system and network administrators who need to resolve hostnames from a list of IPs and test connectivity to specific ports. These tasks are essential for auditing, monitoring, and troubleshooting network environments in Windows-based infrastructures.

This article covers:

• How to read IPs from a file.
• How to resolve hostnames using PowerShell and .NET libraries.
• How to test connectivity on specific ports using Test-NetConnection.

Adjustments for Practical Use:

• The original script has the ports array commented out. It must be uncommented and defined properly to test port accessibility.
• Added minor improvements for clarity and completeness.

Examples:

1. Create a file called ips.txt with IPs (one per line):

   192.168.1.1
   8.8.8.8
   192.168.1.100

2. Complete PowerShell Script (Get-HostnamesAndPorts.ps1):

   
   # Lista de IPs
   $ips = Get-Content -Path "./ips.txt"

Lista de Portas para testar

$ports = @(80, 443, 21, 25) # Modifique conforme necessário

Função para obter o hostname a partir do IP

function Get-Hostname { param ( [string]$ip ) try { $hostname = [System.Net.Dns]::GetHostEntry($ip).HostName } catch { $hostname = "Hostname não encontrado" } return $hostname }

Obter hostnames

Write-Output "=== RESOLUÇÃO DE HOSTNAMES ===" foreach ($ip in $ips) { $hostname = Get-Hostname -ip $ip Write-Output "$ip : $hostname" }

Testar conectividade nas portas

Write-Output "`n=== TESTE DE PORTAS ===" foreach ($ip in $ips) { foreach ($port in $ports) { $result = Test-NetConnection -ComputerName $ip -Port $port if ($result.TcpTestSucceeded) { Write-Output "$ip está acessível na porta $port." } else { Write-Output "$ip está bloqueado na porta $port." } } }

3. **Executar o Script via PowerShell:**
```powershell
.\Get-HostnamesAndPorts.ps1

This script helps validate DNS resolution and port accessibility across your network, making it easier to identify misconfigurations, offline devices, or firewall issues.