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C# Sockets communication between two computers

i want to let 2 c# apps each one is on a separate computer and both connected to the same ADSL router to send messages to each other i know that we have to use Sockets and tried many solutions on the internet but they are all working at the same computer but not working on a separate computers.
i believe that the problem is in the ip addresses but i tried a lot with no good results
is there any simple code to help please
i tried this function on server side
public static void StartServer()
{
IPHostEntry host = Dns.GetHostEntry("DESKTOP-SBJHC7I");
IPAddress ipAddress = host.AddressList[0];
Console.WriteLine(ipAddress.ToString());
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
try
{
// Create a Socket that will use Tcp protocol
Socket listener = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
// A Socket must be associated with an endpoint using the Bind method
listener.Bind(localEndPoint);
// Specify how many requests a Socket can listen before it gives Server busy response.
// We will listen 10 requests at a time
listener.Listen(10);
Console.WriteLine("Waiting for a connection...");
Socket handler = listener.Accept();
// Incoming data from the client.
string data = null;
byte[] bytes = null;
while (true)
{
bytes = new byte[1024];
int bytesRec = handler.Receive(bytes);
data += Encoding.ASCII.GetString(bytes, 0, bytesRec);
if (data.IndexOf("<EOF>") > -1)
{
break;
}
}
Console.WriteLine("Text received : {0}", data);
byte[] msg = Encoding.ASCII.GetBytes(data);
handler.Send(msg);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
Console.WriteLine("\n Press any key to continue...");
Console.ReadKey();
}
and this function in the client side
public static void StartClient()
{
byte[] bytes = new byte[1024];
try
{
// Connect to a Remote server
// Get Host IP Address that is used to establish a connection
// In this case, we get one IP address of localhost that is IP : 127.0.0.1
// If a host has multiple addresses, you will get a list of addresses
IPHostEntry host = Dns.GetHostEntry("DESKTOP-SBJHC7I");
IPAddress ipAddress = host.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket sender = new Socket(ipAddress.AddressFamily,
SocketType.Stream, ProtocolType.Tcp);
// Connect the socket to the remote endpoint. Catch any errors.
try
{
// Connect to Remote EndPoint
sender.Connect(remoteEP);
Console.WriteLine("Socket connected to {0}",
sender.RemoteEndPoint.ToString());
// Encode the data string into a byte array.
byte[] msg = Encoding.ASCII.GetBytes("This is a test<EOF>");
// Send the data through the socket.
int bytesSent = sender.Send(msg);
// Receive the response from the remote device.
int bytesRec = sender.Receive(bytes);
Console.WriteLine("Echoed test = {0}",
Encoding.ASCII.GetString(bytes, 0, bytesRec));
// Release the socket.
sender.Shutdown(SocketShutdown.Both);
sender.Close();
}
catch (ArgumentNullException ane)
{
Console.WriteLine("ArgumentNullException : {0}", ane.ToString());
}
catch (SocketException se)
{
Console.WriteLine("SocketException : {0}", se.ToString());
}
catch (Exception e)
{
Console.WriteLine("Unexpected exception : {0}", e.ToString());
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

please make sure that your client is connected to the same IP on which server is started. because it seems in your code that your client connecting to host which you getting it from localhost identity. For your testing purpose please hardcode the Server's IP address in your Remoteendpoint. if still the issue same then I will share code to test on a different networks.

From client cancel server socket

Have a large slow feed over a .NET asynchronous socket. Data is coming from instruments so can be 1 row a second (or more). Some times it can just stall.
Using there two examples from MSDN
asynchronous-client-socket-example
asynchronous-server-socket-example
I have a requirement from the socket client stop the transfer from the server mid stream. Each message is pretty small. Do not need to stop mid message. Need to be able to stop the loop - can receive 1000s of small messages (to client).
My thought is to save a reference to client and call:
client.Shutdown(SocketShutdown.Both);
client.Close();
Is this the correct approach?
private static Socket client;
private static void StartClient()
{
// Connect to a remote device.
try
{
// Establish the remote endpoint for the socket.
// The name of the
// remote device is "host.contoso.com".
//IPHostEntry ipHostInfo = Dns.GetHostEntry("host.contoso.com"); Dns.GetHostName()
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);
// Create a TCP/IP socket.
Socket client = new Socket(ipAddress.AddressFamily,
SocketType.Stream, ProtocolType.Tcp);
//client = new Socket(ipAddress.AddressFamily,
// SocketType.Stream, ProtocolType.Tcp);
// Connect to the remote endpoint.
client.BeginConnect(remoteEP,
new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();
// Send test data to the remote device.
Send(client, "This is a test<EOF>");
sendDone.WaitOne();
// Receive the response from the remote device.
Receive(client);
receiveDone.WaitOne();
// Write the response to the console.
Console.WriteLine("Response received : {0}", response);
// Release the socket.
client.Shutdown(SocketShutdown.Both);
client.Close();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

Tcp Socket server in C#

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();
}

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);

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];

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.

send socket request from .net web service (asmx)

I went to request to open socket from web service to be like notification when the database change . The client is request to web service when it's connection to internet to apply to web service to get his IP Address then web service can send in this IP socket when database change . And client have socket open response the request .
Code of web service in Remote host
[WebMethod]
public string GetMyIpAddress()
{
string adree = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]; //get client request ip address
byte[] bytes = new byte[1024];
try
{
IPAddress ipaddress = IPAddress.Parse(adree);
IPEndPoint remote = new IPEndPoint(ipaddress, 1093);
Socket sender = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
sender.Connect(remote);
byte[] meg = Encoding.ASCII.GetBytes("This is a test<EOF>"); // send message to client in it's ip address
int bytesend = sender.Send(meg);
int byterecive = sender.Receive(bytes);
string red = Encoding.ASCII.GetString(bytes, 0, byterecive);
sender.Shutdown(SocketShutdown.Both);
sender.Close();
return(red);
}
catch (Exception e)
{
return(e.ToString());
}
}
Code of client socket
class Program
{
public static string data = null;
static void Main(string[] args)
{
byte[] bytes = new byte[1024];
IPHostEntry iphostinfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipaddress = iphostinfo.AddressList[0];
IPEndPoint localendpoint = new IPEndPoint(ipaddress, 1093);
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
listener.Bind(localendpoint);
listener.Listen(10);
while (true)
{
Console.WriteLine("Waiting for a connection...");
Socket hander = listener.Accept();
data = null;
while (true)
{
bytes = new byte[1024];
int bytsize = hander.Receive(bytes);
data += Encoding.ASCII.GetString(bytes, 0, bytsize);
if (data.IndexOf("<EOF>") > -1)
{
break;
}
}
Console.WriteLine("Text received : {0}", data);
byte[] meg = Encoding.ASCII.GetBytes(data);
hander.Send(meg);
hander.Shutdown(SocketShutdown.Both);
hander.Close();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
}
The problem when i request to web service to get my client IP address and send to this IP address for test i get this problem :
System.Net.Sockets.SocketException (0x80004005): A connection attempt failed because the connected party did not properly respond after a period of time, or est ablished connection failed because connected host has failed to respond 41.218.1
9.226:1093
Please help me how can solve this problem ?

C# UDP Server/Client - NAT

Iam trying to send a message (via UDP) from my client to my server. The server should answer this message and if the client receives this answer he should print out a message.
If i run the client and server on my local network everything works fine.
If i try to connect through the internet from another PC outside my network the server receives the request of the client, sends an answer back, but the client never receives this answer. The client and the server are both behind a NAT but i portforwarded the ports at the server´s NAT and the server got its own DNS. I already tried NAT traversal but it gives me the same IP and port adress as the IPEndPoint of the server, after receiveing the request of the client, does.
I´ve got no idea how to fix this, so any guidance would be much appreciated.
Client
public static void Main()
{
Thread receiveThread = new Thread(new ThreadStart(ReceiveData));
receiveThread.Start();
object[] oData = {1};
sendData(oData, 0,0, "Li");
while (true)
{
Console.ReadLine();
}
}
private void receiveData()
{
string receivePort = 8080;
Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
client.ReceiveTimeout = 1000;
IPEndPoint end = new IPEndPoint(IPAddress.Any, receivePort);
client.Bind(end);
while (true)
{
try
{
byte[] data = new byte[1024];
client.Receive(data, 0, data.Length, SocketFlags.None);
object[] receivedObj = Deserialize(data);
string sType = (string)receivedObj[3];
if (sType == "Li")
{
console.WriteLine("received Li");
}
}
catch (Exception err)
{
Console.WriteLine(err.ToString());
}
}
}
public static void sendData(object[] oData, int iFrom, int iTo, string sType)
{
string sendPort = 17171;
UdpClient client = new UdpClient();
string IP = "ThisIsTheDNSofmyServer.com"; //ServerDNS
//string IP = "192.168.xxx.xxx"; //serverIP in LAN
if (IP.StartsWith("T"))
{
IP = (Dns.GetHostAddresses(IP))[0].ToString();
}
IPEndPoint remoteEndPoint = new IPEndPoint(IPAddress.Parse(IP), sendPort);
oData[1] = iFrom;
oData[2] = iTo;
oData[3] = sType;
Byte[] data = Serialize(oData);
client.Send(data, data.Length, remoteEndPoint);
}
The server´s code is almost the same:
public static void Main()
{
Thread receiveThread = new Thread(new ThreadStart(ReceiveData));
receiveThread.Start();
while (true)
{
Console.ReadLine();
}
}
private static void ReceiveData()
{
int receivePort = 17171;
UdpClient client = new UdpClient(receivePort);
while (true)
{
try
{
IPEndPoint anyIP = new IPEndPoint(IPAddress.Any, 0);
byte[] data = new byte[1024];
data = client.Receive(ref anyIP);
object[] receivedObj = Deserialize(data);
//if I receive data send an Answer
sendData(receivedObj, 0,0,"Li",anyIP.Address.ToString());
}
catch (Exception err)
{
Console.WriteLine(err.ToString());
}
}
}
private static void sendData(object[] oData, int iFrom, int iTo, string sType, string IP)
{
int sendPort = 8080;
object[] paket = { oData, iFrom, iTo, sType };
UdpClient client = new UdpClient();
IPEndPoint remoteEndPoint = new IPEndPoint(IPAddress.Parse(IP), sendPort);
client.Send(data, data.Length, remoteEndPoint);
}

i believe this is a port cofniguration issue,
8080 is almost likely to be configured as alternate http
"The UdpClient you use to receive datagrams must be created using the multicast port number" from MSDN
Hope this helps and good luck
Krishna

You do not need to do anything unordinary to traverse NAT in the setup you described, you just need to send it from the server back to your client; specifically: you must send back to the end point, i.e. IP and port, you received it on.
client.Send(data, data.Length, remoteEndPoint); // remoteEndPoint is the IPEndPoint you got the datagram on