TCP Port Listener

I was creating a DMZ and needed a tool to test my port forwarding I didn’t feel like downloading a program so I created this very simple piece of code to just listen on a port of my choice and print when I can make a connection. Only tests TCP (not UDP).

 

Use it as follows:

PortListener <Port>

   1: class Program

   2:    {

   3:        

   4:        static void Main(string[] args)

   5:        {

   6:            new Program().Run(args);

   7:           

   8:        }

   9:  

  10:        private void Run(string[] args)

  11:        {

  12:            int port = Int32.Parse(args[0]);

  13:            Console.WriteLine("Started listening on port: {0}", port);

  14:            var server = new TcpListener(IPAddress.Any, port);

  15:            server.Start();

  16:            server.BeginAcceptSocket(new AsyncCallback(server_onAccept), server);

  17:  

  18:            Console.WriteLine("Press any key to exit...");

  19:            Console.ReadKey();

  20:        }

  21:  

  22:        void server_onAccept(IAsyncResult ar)

  23:        {

  24:            var server = ((TcpListener)ar.AsyncState);

  25:            var socket = server.EndAcceptSocket(ar);

  26:            

  27:            Console.WriteLine(string.Format("Socket {0} Connected",socket.RemoteEndPoint.ToString()));

  28:            server.BeginAcceptSocket(new AsyncCallback(server_onAccept), server);

  29:        }

  30:    }

 

Download the source here:

 

https://github.com/TheWalkingDev/Projects/tree/master/DevTools/PortListener/PortListener