How do I get process name of an open port in C#?

After some searching, I've adapted Cheyne Wallace's solution into a static class with one property that returns a mapping of Processes to Ports in the form of a list using NetStat.

Here's the class:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text.RegularExpressions;

namespace MyNamespace
{
    /// <summary>
    /// Static class that returns the list of processes and the ports those processes use.
    /// </summary>
    public static class ProcessPorts
    {
        /// <summary>
        /// A list of ProcesesPorts that contain the mapping of processes and the ports that the process uses.
        /// </summary>
        public static List<ProcessPort> ProcessPortMap
        {
            get
            {
                return GetNetStatPorts();
            }
        }


        /// <summary>
        /// This method distills the output from netstat -a -n -o into a list of ProcessPorts that provide a mapping between
        /// the process (name and id) and the ports that the process is using.
        /// </summary>
        /// <returns></returns>
        private static List<ProcessPort> GetNetStatPorts()
        {
            List<ProcessPort> ProcessPorts = new List<ProcessPort>();

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

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

                    Proc.StartInfo = StartInfo;
                    Proc.Start();

                    StreamReader StandardOutput = Proc.StandardOutput;
                    StreamReader StandardError = Proc.StandardError;

                    string NetStatContent = StandardOutput.ReadToEnd() + StandardError.ReadToEnd();
                    string NetStatExitStatus = Proc.ExitCode.ToString();

                    if (NetStatExitStatus != "0")
                    {
                        Console.WriteLine("NetStat command failed.   This may require elevated permissions.");
                    }

                    string[] NetStatRows = Regex.Split(NetStatContent, "\r\n");

                    foreach (string NetStatRow in NetStatRows)
                    {
                        string[] Tokens = Regex.Split(NetStatRow, "\\s+");
                        if (Tokens.Length > 4 && (Tokens[1].Equals("UDP") || Tokens[1].Equals("TCP")))
                        {
                            string IpAddress = Regex.Replace(Tokens[2], @"\[(.*?)\]", "1.1.1.1");
                            try
                            {
                                ProcessPorts.Add(new ProcessPort(
                                    Tokens[1] == "UDP" ? GetProcessName(Convert.ToInt16(Tokens[4])) : GetProcessName(Convert.ToInt16(Tokens[5])),
                                    Tokens[1] == "UDP" ? Convert.ToInt16(Tokens[4]) : Convert.ToInt16(Tokens[5]),
                                    IpAddress.Contains("1.1.1.1") ? String.Format("{0}v6", Tokens[1]) : String.Format("{0}v4", Tokens[1]),
                                    Convert.ToInt32(IpAddress.Split(':')[1])
                                ));
                            }
                            catch
                            {
                                Console.WriteLine("Could not convert the following NetStat row to a Process to Port mapping.");
                                Console.WriteLine(NetStatRow);
                            }
                        }
                        else
                        {
                            if (!NetStatRow.Trim().StartsWith("Proto") && !NetStatRow.Trim().StartsWith("Active") && !String.IsNullOrWhiteSpace(NetStatRow))
                            {
                                Console.WriteLine("Unrecognized NetStat row to a Process to Port mapping.");
                                Console.WriteLine(NetStatRow);
                            }
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            return ProcessPorts;
        }

        /// <summary>
        /// Private method that handles pulling the process name (if one exists) from the process id.
        /// </summary>
        /// <param name="ProcessId"></param>
        /// <returns></returns>
        private static string GetProcessName(int ProcessId)
        {
            string procName = "UNKNOWN";

            try
            {
                procName = Process.GetProcessById(ProcessId).ProcessName;
            }
            catch { }

            return procName;
        }
    }

    /// <summary>
    /// A mapping for processes to ports and ports to processes that are being used in the system.
    /// </summary>
    public class ProcessPort
    {
        private string _ProcessName = String.Empty;
        private int _ProcessId = 0;
        private string _Protocol = String.Empty;
        private int _PortNumber = 0;

        /// <summary>
        /// Internal constructor to initialize the mapping of process to port.
        /// </summary>
        /// <param name="ProcessName">Name of process to be </param>
        /// <param name="ProcessId"></param>
        /// <param name="Protocol"></param>
        /// <param name="PortNumber"></param>
        internal ProcessPort (string ProcessName, int ProcessId, string Protocol, int PortNumber)
        {
            _ProcessName = ProcessName;
            _ProcessId = ProcessId;
            _Protocol = Protocol;
            _PortNumber = PortNumber;
        }

        public string ProcessPortDescription
        {
            get
            {
                return String.Format("{0} ({1} port {2} pid {3})", _ProcessName, _Protocol, _PortNumber, _ProcessId);
            }
        }
        public string ProcessName
        {
            get { return _ProcessName; }
        }
        public int ProcessId
        {
            get { return _ProcessId; }
        }
        public string Protocol
        {
            get { return _Protocol; }
        }
        public int PortNumber
        {
            get { return _PortNumber; }
        }
    }
}

Calling from a simple console application may look like:

using System;

namespace MyNamespace
{
    class Program
    {
        static void Main(string[] args)
        {
            foreach (ProcessPort p in ProcessPorts.ProcessPortMap.FindAll(x => x.ProcessName.ToLower() == "myprocess"))  //extension is not needed.
            {
                Console.WriteLine(p.ProcessPortDescription);
            }

            foreach (ProcessPort p in ProcessPorts.ProcessPortMap.FindAll(x => x.PortNumber == 4444))
            {
                Console.WriteLine(p.ProcessPortDescription);
            }

            Console.WriteLine("Press any key to continue...");
            Console.ReadLine();
        }
    }
}

http://www.codeproject.com/KB/IP/iphlpapi.aspx might also help

You can execute netstat -anb and process output.