7

I have found this piece of code on the internet: it does not open a server listening on port 11000, as I hoped.

What can be the problem? I normally code in Delphi, so I am little lost. I have made a corresponding client in Delphi, which works.

I am using demo version of C# 2015.

 public static void StartListening() { // Data buffer for incoming data. byte[] bytes = new Byte[1024]; // Establish the local endpoint for the socket. // Dns.GetHostName returns the name of the // host running the application. IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName()); IPAddress ipAddress = ipHostInfo.AddressList[0]; IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000); // Create a TCP/IP socket. Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); // Bind the socket to the local endpoint and // listen for incoming connections. try { listener.Bind(localEndPoint); listener.Listen(10); // Start listening for connections. while (true) { //Console.WriteLine("Waiting for a connection..."); // Program is suspended while waiting for an incoming connection. Socket handler = listener.Accept(); data = null; // An incoming connection needs to be processed. while (true) { bytes = new byte[1024]; int bytesRec = handler.Receive(bytes); data += Encoding.ASCII.GetString(bytes, 0, bytesRec); if (data.IndexOf("#") > -1) { break; } } // Show the data on the console. //Console.WriteLine("Text received : {0}", data); // Echo the data back to the client. byte[] msg = Encoding.ASCII.GetBytes(data); handler.Send(msg); handler.Shutdown(SocketShutdown.Both); handler.Close(); } } catch (Exception e) { Console.WriteLine(e.ToString()); } //Console.WriteLine("\nPress ENTER to continue..."); //Console.Read(); }
Improve this question
2
  • What is the exception from bind? Commented Sep 19, 2016 at 12:29
  • Thank you very much. No exception on bind. Commented Sep 26, 2016 at 6:10

3 Answers 3

Reset to default
9

The problem might be here: Whats the IP address of ipHostInfo.AddressList[0] ? It might be the loop-back. I never restrict my server endpoint to an ip-adress unless I need to, but then I will specify it in a configfile.

IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, 11000);
Improve this answer
Sign up to request clarification or add additional context in comments.

1 Comment

That was the problem, exactly, Thank you very much.
1

As per Jeroen's answer, encountered per .NET's Synchronous Server Socket Example. When listening/connecting to localhost, one should rather use

IPAddress ipAddress = IPAddress.Parse("127.0.0.1");

instead of

// Establish the local endpoint for the socket. // Dns.GetHostName returns the name of the // host running the application. IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName()); IPAddress ipAddress = ipHostInfo.AddressList[0];
Improve this answer

Comments

0

Thanks for feedback. I found som other, older code:

TcpListener serverSocket = new TcpListener(11000);

that does the job. I know it is depreciated, but it works, actually.

Improve this answer

1 Comment

If you take a look into the code you'll see it does exactly the same as @Jeroen mentioned in his answer. So you should at least upvote his answer and/or accept it.