Networking in windows service - windows

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.ServiceProcess;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
using System.Threading;
namespace EchoServer
{
public class SynchronousSocketListener
{
// Incoming data from the client.
public static string data = null;
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.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 31337);
// Create a TCP/IP socket.
Socket listener = new Socket(ipAddress.AddressFamily,
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();
String msg = "This is a malicious service, muahahahahahahaha!!!";
byte[] encoded_msg = Encoding.ASCII.GetBytes(msg);
handler.Send(encoded_msg);
// An incoming connection needs to be processed.
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
}
}
namespace MaliciousService
{
public partial class Service1 : ServiceBase
{
public Service1()
{
InitializeComponent();
}
protected override void OnStart(string[] args)
{
Thread t = new Thread(EchoServer.SynchronousSocketListener.StartListening);
t.Start();
}
protected override void OnStop()
{
}
}
}
I built this simple service that creates a synchronous socket listener which binds on localhost in port 31337 in a thread. but after I run the service, it seems that the port isn't taken, and the socket calls failed. any ideas why this could happen? (the server was copied from microsoft documentation)

Answer 1

Problem solved. the lines
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 31337);
Didn't bind me to loopback. I changed it to
IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 31337);