C# Get Active Ports and Associated Process Names. This code will parse the output from a "netstat -a -n -o" and retrieve a list of active listening ports, along with the associated PID. The PID is then resolved to a process name so we can see exactly which port is attached to which process.

NetStatPortsAndProcessNames.cs

// ===============================================
// The Method That Parses The NetStat Output
// And Returns A List Of Port Objects
// ===============================================
public static List<Port> GetNetStatPorts()
{
  var Ports = new List<Port>();

  try {
    using (Process p = new Process()) {

      ProcessStartInfo ps = new ProcessStartInfo();
      ps.Arguments = "-a -n -o";
      ps.FileName = "netstat.exe";
      ps.UseShellExecute = false;
      ps.WindowStyle = ProcessWindowStyle.Hidden;
      ps.RedirectStandardInput = true;
      ps.RedirectStandardOutput = true;
      ps.RedirectStandardError = true;

      p.StartInfo = ps;
      p.Start();

      StreamReader stdOutput = p.StandardOutput;
      StreamReader stdError = p.StandardError;

      string content = stdOutput.ReadToEnd() + stdError.ReadToEnd();
      string exitStatus = p.ExitCode.ToString();
      
      if (exitStatus != "0") {
        // Command Errored. Handle Here If Need Be
      }

      //Get The Rows
      string[] rows = Regex.Split(content, "\r\n");
      foreach (string row in rows) {
        //Split it baby
        string[] tokens = Regex.Split(row, "\\s+");
        if (tokens.Length > 4 && (tokens[1].Equals("UDP") || tokens[1].Equals("TCP"))) {
          string localAddress = Regex.Replace(tokens[2], @"\[(.*?)\]", "1.1.1.1");
          Ports.Add(new Port {
            protocol = localAddress.Contains("1.1.1.1") ? String.Format("{0}v6",tokens[1]) : String.Format("{0}v4",tokens[1]),
            port_number = localAddress.Split(':')[1],
            process_name = tokens[1] == "UDP" ? LookupProcess(Convert.ToInt16(tokens[4])) : LookupProcess(Convert.ToInt16(tokens[5]))
          });
        }
      }
    }
  } 
  catch (Exception ex) 
  { 
    Console.WriteLine(ex.Message)
  }
  return Ports;
}

public static string LookupProcess(int pid) 
{
  string procName;
  try { procName = Process.GetProcessById(pid).ProcessName; } 
  catch (Exception) { procName = "-";}
  return procName;
}

// ===============================================
// The Port Class We're Going To Create A List Of
// ===============================================
public class Port
{
  public string name
  {
    get
    {
      return string.Format("{0} ({1} port {2})",this.process_name, this.protocol, this.port_number);
    }
    set { }
  }
  public string port_number { get; set; }
  public string process_name { get; set; }
  public string protocol { get; set; }
}

@asheroto MSDN Code Gallery was closed in 2019, the stuff is now on Github but it's all buried.

https://github.com/microsoftarchive/msdn-code-gallery-microsoft/tree/master/OneCodeTeam/C%23%20Sample%20to%20list%20all%20the%20active%20TCP%20and%20UDP%20connections%20using%20Windows%20Form%20appl

A process number can be higher than int16 :).

Is there a license for this gist?

Sorry guys, I wrote this code about a decade ago or more. I havn't written any C# since back around then so do with it as you will.
There's no license here, use it, modify it, if it helps you out, do what you want with it.