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No connection could be made because the target computer actually refused 127.0.0.1:1080 - tcp-client

I created a project in c# to simulate a tcp client in c# using visual studio 2017 to understand how TCP/IP communications work at a very high level.
The problem is that the code bellow is throwing an exception "No connection could be made because the target computer actually refused 127.0.0.1:1080"
namespace SimpleTcpEchoClient
{
public class Program
{
static void Main(string[] args)
{
TcpClient ourTcpClient = null;
NetworkStream networkStream = null;
try
{
//initiate a TCP client connection to local loopback address at port 1080
ourTcpClient = new TcpClient();
ourTcpClient.Connect(new IPEndPoint(IPAddress.Loopback, 1080)); //HERE IS WHERE THE EXCEPTION IS THROWN
Console.WriteLine("Connected to server....");
//get the IO stream on this connection to write to
networkStream = ourTcpClient.GetStream();
//use UTF-8 and either 8-bit encoding due to MLLP-related recommendations
var messageToTransmit = "Hello from Client";
var byteBuffer = Encoding.UTF8.GetBytes(messageToTransmit);
//send a message through this connection using the IO stream
networkStream.Write(byteBuffer, 0, byteBuffer.Length);
Console.WriteLine("Data was sent data to server successfully....");
var bytesReceivedFromServer = networkStream.Read(byteBuffer, 0, byteBuffer.Length);
// Our server for this example has been designed to echo back the message
// keep reading from this stream until the message is echoed back
while (bytesReceivedFromServer < byteBuffer.Length)
{
bytesReceivedFromServer = networkStream.Read(byteBuffer, 0, byteBuffer.Length);
if (bytesReceivedFromServer == 0)
{
//exit the reading loop since there is no more data
break;
}
}
var receivedMessage = Encoding.UTF8.GetString(byteBuffer);
Console.WriteLine("Received message from server: {0}", receivedMessage);
Console.WriteLine("Press any key to exit program...");
Console.ReadLine();
}
catch (Exception ex)
{
//display any exceptions that occur to console
Console.WriteLine(ex.Message);
}
finally
{
//close the IO strem and the TCP connection
networkStream?.Close();
ourTcpClient?.Close();
}
}
}
}
I already tried to change the port but without success!
Can someone please help me?

It is solved now, my server was running on port 1081 instead of 1080 :)

Tcp Server/Client Application to communicate with other PCs

i'm trying to make an application which allows the connection between 2 PCs(i planned on making it multi threaded later but lets keep it more simple at the beginning). This could be either used for chatting or sending data to the other pc and he does something to the data and sends it back.
This is my coding so far:
Server:
class Program
{
private static StreamWriter serverStreamWriter;
private static StreamReader serverStreamReader;
private static bool StartServer()
{
//setting up Listener
TcpListener tcpServerListener = new TcpListener(IPAddress.Any, 56765);
tcpServerListener.Start();
Console.WriteLine("Server Started!");
Console.WriteLine("Waiting for Connection...");
Socket serverSocket = tcpServerListener.AcceptSocket();
try
{
if (serverSocket.Connected)
{
Console.WriteLine("Client connected to Server!");
//open network stream on accepted socket
NetworkStream serverSockStream = new NetworkStream(serverSocket);
serverStreamWriter = new StreamWriter(serverSockStream);
serverStreamReader = new StreamReader(serverSockStream);
}
}
catch (Exception e)
{
Console.WriteLine(e.StackTrace);
return false;
}
return true;
}
static bool once = false;
static void Main(string[] args)
{
//Set Console Window Stuff
Console.Title = "Server";
Console.BackgroundColor = ConsoleColor.Black;
Console.ForegroundColor = ConsoleColor.Green;
Console.BufferWidth = 120;
Console.Clear();
//Start Server
if (!StartServer())
Console.WriteLine("Error while Starting Server!");
//Waiting till Client sends Something
while (true)
{
string data = "Append Something to Me - ";
if (!once)//that check -.-
{
serverStreamWriter.WriteLine(data);
serverStreamWriter.Flush();
once = true;
}
Console.WriteLine("Client: " + serverStreamReader.ReadLine());
if (serverStreamReader.ReadLine() != data)
{
serverStreamWriter.WriteLine(data);
serverStreamWriter.Flush();
}
}
}
}
Client:
class Program
{
private static StreamReader clientStreamReader;
private static StreamWriter clientStreamWriter;
private static bool ConnectToServer()
{
try
{
TcpClient tcpClient = new TcpClient("127.0.0.1", 56765);
Console.WriteLine("Connected to Server!");
NetworkStream clientSockStream = tcpClient.GetStream();
clientStreamReader = new StreamReader(clientSockStream);
clientStreamWriter = new StreamWriter(clientSockStream);
}
catch (Exception e)
{
Console.WriteLine(e.StackTrace);
return false;
}
return true;
}
private static void SendToServer(string message)
{
try
{
clientStreamWriter.WriteLine(message);
clientStreamWriter.Flush();
}
catch (Exception se)
{
Console.WriteLine(se.StackTrace);
}
}
static void Main(string[] args)
{
//Set Console Window Stuff
Console.Title = "Client";
Console.BackgroundColor = ConsoleColor.Black;
Console.ForegroundColor = ConsoleColor.Red;
Console.BufferWidth = 120;
Console.Clear();
if (!ConnectToServer())
Console.WriteLine("Error while Connecting to Server!");
SendToServer("Send Me Data...");
//Waiting till Server sends Something
while (true)
{
string response = clientStreamReader.ReadLine();
Console.WriteLine(response + "|| Appending Text...");
response += "Appended Text!";
Console.WriteLine("Sended " + response + " back to server!");
SendToServer(response);
}
}
}
Even though this isn't really good coding, it works for me, BUT the main problem with this is it only works on my local machine. How would i make it so if i run the server app on my pc and my friend runs the client app on his pc those two connect!? Help would be really great since i wasn't able to found a detailed tutorial or such and i only created this Account to ask for help here :)

TcpClient tcpClient = new TcpClient("localhost", 3333);
Instead of "localhost", use the remote machine's address here.
Edit:
You don't seem to understand how this connection process works, so I'll try to explain it a little better.
Your server is opening up a socket on port 3333, listening for any connections. This process does not need any external IP adress.
You clients are trying to connect to the server. They need to know what server they're connecting to, so you need to supply them with an IP address. An example would be something like
TcpClient tcpClient = new TcpClient("127.0.0.1", 3333);
//this is identical to using "localhost"
There's no way for you to get around at some point using a remote address in the connection protocol. You can't just tell the client "connect on port 3333" and expect it to know exactly where it needs to connect.
The comment explaining how to resolve a local IP address isn't useful in your case, because what you ended up doing was just telling the client to connect to itself, as you resolved the client's IP address and tried to connect to that.
However, you can have multiple clients connect to the same server. In this case you won't need multiple remote IP addresses, you just tell all the clients to connect to the same remote address and then handle that on the server. This is where the RemoteEndPoint comes into effect.
At the server level you can use the RemoteEndPoint to find the IP address of the clients connecting to it, and use this IP address to return information to those clients.
All in all, you WILL have to use some hardcoded address for your initial
TcpClient tcpClient = new TcpClient(address, 3333);
step. There's no way around this.

Could not send second message over TCP/IP

I am trying to send message over TCP/IP in c# application using TCPClient and TCPListner classes
Following is my code which i got from codeproject site.
Client code written over btn click
try
{
TcpClient tcpclnt = new TcpClient();
Console.WriteLine("Connecting.....");
tcpclnt.Connect("192.168.0.102", 8001);
// use the ipaddress as in the server program
Console.WriteLine("Connected");
//Console.Write("Enter the string to be transmitted : ");
String str = textBox1.Text;
Stream stm = tcpclnt.GetStream();
ASCIIEncoding asen = new ASCIIEncoding();
byte[] ba = asen.GetBytes(str);
Console.WriteLine("Transmitting.....");
stm.Write(ba, 0, ba.Length);
byte[] bb = new byte[100];
int k = stm.Read(bb, 0, 100);
for (int i = 0; i < k; i++)
Console.Write(Convert.ToChar(bb[i]));
tcpclnt.Close();
}
catch (Exception ex)
{
Console.WriteLine("Error..... " + ex.Message);
}
Server code written on form_load
try
{
IPAddress ipAd = IPAddress.Parse("192.168.0.102");
// use local m/c IP address, and
// use the same in the client
/* Initializes the Listener */
TcpListener myList = new TcpListener(ipAd, 8001);
/* Start Listeneting at the specified port */
myList.Start();
Console.WriteLine("The server is running at port 8001...");
Console.WriteLine("The local End point is :" +
myList.LocalEndpoint);
Console.WriteLine("Waiting for a connection.....");
Socket s = myList.AcceptSocket();
Console.WriteLine("Connection accepted from " + s.RemoteEndPoint);
byte[] b = new byte[100];
int k = s.Receive(b);
Console.WriteLine("Recieved...");
string str = string.Empty;
for (int i = 0; i < k; i++)
{
Console.Write(Convert.ToChar(b[i]));
str = str + Convert.ToChar(b[i]);
}
label1.Text = str;
ASCIIEncoding asen = new ASCIIEncoding();
s.Send(asen.GetBytes("The string was recieved by the server."));
Console.WriteLine("\nSent Acknowledgement");
/* clean up */
s.Close();
// myList.Stop();
}
Here on client, i m sending string written in textbox over tcp and it well recieved by server.
But when i trying to send another string, it fails without any exception and client application hangs for infinite time.
What is wrong here ?

Server should always be in listening mode, i.e the server code should be in while loop such that it can accept clients continuously. Your server will accept one client and then close itself. Therefore, if you click client's button, a new client tries to connect to server, but now the server won't be available.

Looking at the code you provided, the server only attempts to read 1 message from the client, so needs to be put in a loop to read the multiple incoming messages from the client, process the message and send response and then get more messages.
Note also that the server currently expects only one client to ever connect, processes that client and then closes.
The client is set up basically the same in the example, so you cant modify how one works without also modifying the other.

Socket Programming c# / Client-Server communication

I am trying to make 2 programs (in console application) in .NET that communicate together through the web (the code is from a video that you can find below, I am just trying to make the code work before adapting it). Forgive me, I'm not an experienced programmer.
I have a server and a client, they work perfectly when I run both of them on my computer (locally).
I can connect multiple clients to the server, send requests and get a response.
I am facing the problem when i run the server on a computer and the client on an other one and I try to connect through the internet.
I can connect to the server but communication does not work, there is no data exchange when try to request time as an example. I think that the problem is mostly coming from the network itself than the code.
Here's the code for the server:
class Program
{
private static Socket _serverSocket;
private static readonly List<Socket> _clientSockets = new List<Socket>();
private const int _BUFFER_SIZE = 2048;
private const int _PORT = 50114;
private static readonly byte[] _buffer = new byte[_BUFFER_SIZE];
static void Main()
{
Console.Title = "Server";
SetupServer();
Console.ReadLine(); // When we press enter close everything
CloseAllSockets();
}
private static void SetupServer()
{
// IPAddress addip = GetBroadcastAddress();
Console.WriteLine("Setting up server...");
_serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_serverSocket.Bind(new IPEndPoint(IPAddress.Any , _PORT));
_serverSocket.Listen(5);
_serverSocket.BeginAccept(AcceptCallback, null);
Console.WriteLine("Server setup complete");
}
/// <summary>
/// Close all connected client (we do not need to shutdown the server socket as its connections
/// are already closed with the clients)
/// </summary>
private static void CloseAllSockets()
{
foreach (Socket socket in _clientSockets)
{
socket.Shutdown(SocketShutdown.Both);
socket.Close();
}
_serverSocket.Close();
}
private static void AcceptCallback(IAsyncResult AR)
{
Socket socket;
try
{
socket = _serverSocket.EndAccept(AR);
}
catch (ObjectDisposedException) // I cannot seem to avoid this (on exit when properly closing sockets)
{
return;
}
_clientSockets.Add(socket);
socket.BeginReceive(_buffer, 0, _BUFFER_SIZE, SocketFlags.None, ReceiveCallback, socket);
Console.WriteLine("Client connected, waiting for request...");
_serverSocket.BeginAccept(AcceptCallback, null);
}
private static void ReceiveCallback(IAsyncResult AR)
{
Socket current = (Socket)AR.AsyncState;
int received;
try
{
received = current.EndReceive(AR);
}
catch (SocketException)
{
Console.WriteLine("Client forcefully disconnected");
current.Close(); // Dont shutdown because the socket may be disposed and its disconnected anyway
_clientSockets.Remove(current);
return;
}
byte[] recBuf = new byte[received];
Array.Copy(_buffer, recBuf, received);
string text = Encoding.ASCII.GetString(recBuf);
Console.WriteLine("Received Text: " + text);
if (text.ToLower() == "get time") // Client requested time
{
Console.WriteLine("Text is a get time request");
byte[] data = Encoding.ASCII.GetBytes(DateTime.Now.ToLongTimeString());
current.Send(data);
Console.WriteLine("Time sent to client");
}
else if (text.ToLower() == "exit") // Client wants to exit gracefully
{
// Always Shutdown before closing
current.Shutdown(SocketShutdown.Both);
current.Close();
_clientSockets.Remove(current);
Console.WriteLine("Client disconnected");
return;
}
else
{
Console.WriteLine("Text is an invalid request");
byte[] data = Encoding.ASCII.GetBytes("Invalid request");
current.Send(data);
Console.WriteLine("Warning Sent");
}
current.BeginReceive(_buffer, 0, _BUFFER_SIZE, SocketFlags.None, ReceiveCallback, current);
}
}
And here the client code:
class Program
{
private static readonly Socket _clientSocket = new Socket
(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
private const int _PORT = 50114;
static void Main()
{
Console.Title = "Client";
ConnectToServer();
RequestLoop();
Exit();
}
private static void ConnectToServer()
{
int attempts = 0;
while (!_clientSocket.Connected)
{
try
{
attempts++;
Console.WriteLine("Connection attempt " + attempts);
_clientSocket.Connect("IpAddr", _PORT);
}
catch (SocketException)
{
Console.Clear();
}
}
Console.Clear();
Console.WriteLine("Connected");
}
private static void RequestLoop()
{
Console.WriteLine(#"<Type ""exit"" to properly disconnect client>");
while (true)
{
SendRequest();
ReceiveResponse();
}
}
/// <summary>
/// Close socket and exit app
/// </summary>
private static void Exit()
{
SendString("exit"); // Tell the server we re exiting
_clientSocket.Shutdown(SocketShutdown.Both);
_clientSocket.Close();
Environment.Exit(0);
}
private static void SendRequest()
{
Console.Write("Send a request: ");
string request = Console.ReadLine();
SendString(request);
if (request.ToLower() == "exit")
{
Exit();
}
}
/// <summary>
/// Sends a string to the server with ASCII encoding
/// </summary>
private static void SendString(string text)
{
byte[] buffer = Encoding.ASCII.GetBytes(text);
_clientSocket.Send(buffer, 0, buffer.Length, SocketFlags.None);
}
private static void ReceiveResponse()
{
var buffer = new byte[2048];
int received = _clientSocket.Receive(buffer, SocketFlags.None);
if (received == 0) return;
var data = new byte[received];
Array.Copy(buffer, data, received);
string text = Encoding.ASCII.GetString(data);
Console.WriteLine(text);
}
}
static void Main()
{
Console.Title = "Client";
ConnectToServer();
RequestLoop();
Exit();
}
private static void ConnectToServer()
{
int attempts = 0;
while (!_clientSocket.Connected)
{
try
{
attempts++;
Console.WriteLine("Connection attempt " + attempts);
_clientSocket.Connect("IpAddr", _PORT);
}
catch (SocketException)
{
Console.Clear();
}
}
Console.Clear();
Console.WriteLine("Connected");
}
"IpAddr" is a placeholder for the public IP of the router.
This is the video my current code is based on: https://www.youtube.com/watch?v=xgLRe7QV6QI
I took the code directly from it (you can find the 2 code files on the site linked in description).
I run the server, it awaits for a connection. I then run the clients which tries to connect to the server. I connects and on the server it shows the successful connection. The client then sends a request like "get time" and the server is supposed to catch it and respond:
byte[] data = Encoding.ASCII.GetBytes(DateTime.Now.ToLongTimeString());
current.Send(data);
Back to network side:
Here is a list of all the things I have tried, that were the usual main causes of the problem after looking for a solution for about a full day:
I already have a static public IP for the router (so the public IP never changes). Even though, I created a dynamic dns on noip.com.
I gave a static lease to the computer the server runs on, so it has always the same local ip.
I created rules in the windows firewall to make sure the port I use is opened. I did this on both computers trying to communicate.
I forwarded the port on the router so it points to the local ip of the computer the server runs on. (I tried with a lot of different ports, no chance)
I tried activating the "DMZ" on the router but it's most likely not a solution
I tried to create a ASP.NET website which page returns a string, publish it with IIS 7.5 and set it up. Works on localhost but using the public ip like "xx.xxx.xxx.xx:PORT/default/index" I get an error. Yet it shows the website name in the error. Also, when using the local IP of the computer, it doesn't work either (something like 192.168.1.180).
Thanks for you help.

I learned about message framing, Thank you CodeCaster.
For people who are curious about it, here is an interesting link i found about it: http://blog.stephencleary.com/2009/04/message-framing.html
But before trying to change the code, I ran the server on an AWS vps and it worked instantly, the problem was probably comming from my isp or my router. I am just wondering how can it work without handling message framing.

Fixing the cause from a Socket Exception in C#

I'm creating a small server for multiple winform client connecting to it over the internet.
The following code works when it is set to the local address:
Server:
static void Main(string[] args)
{
TcpListener serverSocket = new TcpListener(9000);
TcpClient clientSocket = default(TcpClient);
int counter = 0;
serverSocket.Start();
Console.WriteLine("Chat Server Started ....");
counter = 0;
while ((true))
{
counter += 1;
clientSocket = serverSocket.AcceptTcpClient();
byte[] bytesFrom = new byte[10025];
string dataFromClient = null;
NetworkStream networkStream = clientSocket.GetStream();
networkStream.Read(bytesFrom, 0, (int)clientSocket.ReceiveBufferSize);
dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));
clientsList.Add(dataFromClient, clientSocket);
broadcast(dataFromClient + " Joined ", dataFromClient, false);
Console.WriteLine(dataFromClient + " Joined chat room ");
handleClinet client = new handleClinet();
client.startClient(clientSocket, dataFromClient, clientsList);
}
clientSocket.Close();
serverSocket.Stop();
Console.WriteLine("exit");
Console.ReadLine();
}
Winform Client:
public partial class Form1 : Form
{
System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
NetworkStream serverStream = default(NetworkStream);
string readData = null;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
readData = "Conected to Chat Server ...";
msg();
clientSocket.Connect("127.0.0.1", 9000);
serverStream = clientSocket.GetStream();
byte[] outStream = System.Text.Encoding.ASCII.GetBytes(textBox3.Text + "$");
serverStream.Write(outStream, 0, outStream.Length);
serverStream.Flush();
Thread ctThread = new Thread(getMessage);
ctThread.Start();
}
}
Those piece of code works fine talking to each other over the network.
But when I decide to change this line of code
clientSocket.Connect("127.0.0.1", 9000);
to
clientSocket.Connect("81.62.126.41", 9000);
for my ip address it gives me the following SocketException:
A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
So some things I have tried. Port forwarding port 9000 because I am behind my router. Creating inbound and outbound rules for port 9000. And I have gone to http://www.canyouseeme.org/ while my server is running and the website can in fact see my service.
Anyone know what I can do to resolve this issue?
Here's a pic of netstat when the server is running. Thought it might be helpful.

I have had similar issue.
If you change only one string in your code and it stops working double-check the tools you're using. Some internal proxys could allow/disallow you to communicate with internal (127.0.0.1) or external ip.
Check the same URL in your browser 127.0.0.1:9000 and 81.62.126.41:9000. If it doesn't open for the second case then issue in your firewall or setting up your server to be able for external access, not in your code.
Your exception means that something wrong with your server: you could try open http://81.62.12.32/ and open http://81.62.126.41:9000/ and you will see two different errors.
Conclusion: Issue is not in your code. It's in your web server settings or in firewall set up.