Thread: How to multithread my port scanning app?

I'm creating a small port scanning app which use a port range defined by user.

My problem with the code is that I find it not efficient enough meaning that it ping very slow, especially when ports are not responding meaning that I must wait for the timeout before continuing to next port.

I want to make this small app threaded. The problem here is that I'm kind of blank of how to implement threading in my program.

This is my code which is a method which does the actual checking, the other part of the code is a simple button with for loop for advancing my port number.

Code:

                private void ScanPort(IPAddress address, int port)
        {
            using (TcpClient client = new TcpClient())
            {
                IAsyncResult result = client.BeginConnect(address, port, null, null);

                if (result.AsyncWaitHandle.WaitOne((int)nudTimeout.Value, false)) txtDisplay.AppendText("Port: " + port + " is open." + Environment.NewLine);
                else txtDisplay.AppendText("Port: " + port + " is closed." + Environment.NewLine);
            }
        }

I have read some basic threading tutorial but I just don't know how to implement this piece of code so I can check ports much faster.

Hope for some advices.

Regards.

You don't need to manually create threads with Async sockets.

Originally Posted by theoobe

You don't need to manually create threads with Async sockets.

Well, I'm kind of stuck at this part. I have tried to use asynchronous tcp socket connection but I couldn't figure out how to work it out of articles like this or this and my code doesn't do what I would like it to do, to check ports at least much faster speed without wait for single thread to reach the timeout.

Replace your for loop with Parallel.For