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C# UDPClient not receiving packets over external IP

So here's the thing, i'm creating a server/client environment for a game where a port forwarded computer acts as a server, and clients send the first UDP message to connect and get the accept message then start sending the in-game UDP messages after successfully connecting.
The problem is, when I use the local IPs say the server using 10.0.0.7 and a client is using 10.0.0.4, everything works just fine:
Client sends connect message.
Server receives it.
Servers sends back accept message.
Client receives it
All further messages reach both ends without any problem.
But when I use the external IP:
Client sends connect message.
Server receives it.
Servers sends back accept message.
Client receives it
Both ends can send messages but the client doesn't receive any more messages.
Wanted to know at the end if the problem is somehow from the code, or from what I think it's really from, router, NAT, firewalls or anything like that.
(Note: Client sends to server's 8888 port, and server sends back through the client's local port, as it should be.)
Below is the client code, written for Unity:
void Start()
{
client = new UdpClient();
client.Connect(IPAddress.Parse("<Global IP>"), 8888);
client.BeginReceive(new AsyncCallback(ReadMessage), client);
}
private void ReadMessage(IAsyncResult result)
{
IPEndPoint ipEndPoint = null;
string message = Encoding.ASCII.GetString(client.EndReceive(result, ref ipEndPoint));
print("Got: " + message);
string[] wholeMessages = message.Split('#');
for (int w = 0; w < wholeMessages.Length - 1; w++)
{
string[] parts = wholeMessages[w].Split('$');
if (!connected && parts.Length == 3 && parts[0] == "accept" && int.TryParse(parts[1], out ID))
{
connected = true;
code = parts[2];
}
}
client.BeginReceive(new AsyncCallback(ReadMessage), client);
}
public void SendUDP(string message)
{
client.Send(Encoding.ASCII.GetBytes(message), message.Length);
}

Ok, after several trials and errors this worked for me...
//Server Code
private static UdpClient udpClient;
static void Main(string[] args)
{
Console.WriteLine("Server initiated...");
udpClient = new UdpClient(8888);
}
private static void ReadMessage()
{
while (true)
{
try
{
IPEndPoint IPEP = null;
string message = Encoding.ASCII.GetString(udpClient.Receive(ref IPEP));
}
}
}
private static void SendUDP(IPEndPoint e,string message)
{
new UdpClient().Send(Encoding.ASCII.GetBytes(message), message.Length, e);
}
//Client Code
private IPAddress ip;
void Start()
{
ip = Dns.GetHostAddresses("HOSTNAME")[0];
client = new UdpClient(new IPEndPoint(IPAddress.Any, 0));
udpThread = new Thread(new ThreadStart(ReadMessage))
{
IsBackground = true
};
udpThread.Start();
}
private void ReadMessage()
{
while (true)
{
try
{
IPEndPoint IPEP = null;
byte[] data = client.Receive(ref IPEP);
string message = Encoding.ASCII.GetString(data);
}
}
}
public void SendUDP(string message)
{
client.Send(Encoding.ASCII.GetBytes(message), message.Length, new IPEndPoint(ip, 8888));
}

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 can not receive

I have been searching the internet for a week or two now to find a UDP client program that can send and receive at the same time but there is nothing on this subject for c#. In the last few days I have tried create a UDP client with a thread that receives.
Sending UDP packets works great but the program can not receive for the server i sent to, I believe the server is sending all packets to a different port.
How do i fix this program?
Is there an easier way to do UDP programming like StreamReader and StreamWriter for TCP?
static void CONNECTudp()
{
Console.WriteLine("Host:");
IPAddress ipAddress = Dns.Resolve(Console.ReadLine()).AddressList[0];
Console.WriteLine("Port:");
int Port = int.Parse(Console.ReadLine());
IPEndPoint ipEndPoint = new IPEndPoint(ipAddress, Port);
Thread UDPthread = new Thread(() => CONNECTudpthread(ipEndPoint));
UDPthread.Start();
UdpClient udp = new UdpClient();
do
{
Byte[] sendBytes = Encoding.ASCII.GetBytes(Console.ReadLine());
udp.Send(sendBytes, sendBytes.Length, ipEndPoint);
} while (true);
}
static void CONNECTudpthread(IPEndPoint ipEndPoint)
{
UdpClient udp = new UdpClient();
do
{
try
{
Byte[] receiveBytes = udp.Receive(ref ipEndPoint);
string returnData = Encoding.ASCII.GetString(receiveBytes);
Console.WriteLine(returnData);
}
catch (Exception)
{
}
} while (true);
}

Since UDP is message-oriented and not stream-oriented, there's not really a practical way to use StreamReader and StreamWriter with UDP. Sticking with the message-oriented I/O as in your example is best.
The problem in your code is that you are using two different UdpClient instances for sending and receiving. You don't show the UDP server code, so I can't guarantee that's correct either. But if it is, then if you fix your code to be something more like the following, it should work:
static void CONNECTudp()
{
Console.WriteLine("Host:");
IPAddress ipAddress = Dns.Resolve(Console.ReadLine()).AddressList[0];
Console.WriteLine("Port:");
int Port = int.Parse(Console.ReadLine());
IPEndPoint ipEndPoint = new IPEndPoint(ipAddress, Port);
// Bind port immediately
UdpClient udp = new UdpClient(0);
// Pass UdpClient instance to the thread
Thread UDPthread = new Thread(() => CONNECTudpthread(udp));
UDPthread.Start();
do
{
Byte[] sendBytes = Encoding.ASCII.GetBytes(Console.ReadLine());
udp.Send(sendBytes, sendBytes.Length, ipEndPoint);
} while (true);
}
static void CONNECTudpthread(UdpClient udp)
{
do
{
try
{
// Though it's a "ref", the "remoteEP" argument is really just
// for returning the address of the sender.
IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Any, 0);
Byte[] receiveBytes = udp.Receive(ref ipEndPoint);
string returnData = Encoding.ASCII.GetString(receiveBytes);
Console.WriteLine(returnData);
}
catch (Exception)
{
}
} while (true);
}

C# UdpClient.Receive() not working with multicast no matter what I do

tried to solve this alone for the past I don't even know but no googling will help me here, I would need some advice with this one. I am receiving UDP packets from another PC on my local network every 10 seconds, can see them in wireshark but the application is stuck on the udpClient.Receive() line. The multicast group and port are the right values, checked in main() n+1 times. Please suggest a solution if you have any idea that might help. Thanks.
(I'm trying to receive the server's information so that th application can automaticaly start to communicate vith it via TCP)
class MulticastListener {
private UdpClient udpClient;
private IPEndPoint remoteEndPoint;
IPAddress multicastIP;
private int port;
public MulticastListener(ref IPAddress multicastIP, int port) {
remoteEndPoint = new IPEndPoint(IPAddress.Any, port);
this.multicastIP = multicastIP;
this.port = port;
udpClient = new UdpClient();
udpClient.Client.Bind(remoteEndPoint);
}
public IPEndPoint GetServer() {
try {
udpClient.JoinMulticastGroup(multicastIP);
} catch (ObjectDisposedException e) {
Console.WriteLine("ERROR: The underlying socket has been closed!");
} catch (SocketException e) {
Console.WriteLine("ERROR: An error occurred when accessing the socket!");
} catch (ArgumentException e) {
Console.WriteLine("ERROR: The IP address is not compatible with the AddressFamily value that defines the addressing scheme of the socket!");
}
Byte[] serverInfoBytes = udpClient.Receive(ref remoteEndPoint);
Stream stream = new MemoryStream(serverInfoBytes); //receives a serialised IPEndpoint object
BinaryFormatter formatter = new BinaryFormatter();
udpClient.Close();
return (IPEndPoint)formatter.Deserialize(stream);
}
}

As I commented, your code works fine for me 100% as is. I would check you are sending on the same subnet you are receiving on. Perhaps your sender is not configured to the right interface?
Perhaps it would help to try out a different sender, here is what I used to test:
static void Main(string[] args)
{
//Configuration
var interfaceIp = IPAddress.Parse("192.168.9.121");
var interfaceEndPoint = new IPEndPoint(interfaceIp, 60001);
var multicastIp = IPAddress.Parse("230.230.230.230");
var multicastEndPoint = new IPEndPoint(multicastIp, 60001);
//initialize the socket
var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
socket.ExclusiveAddressUse = false;
socket.MulticastLoopback = false;
socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, 1);
MulticastOption option = new MulticastOption(multicastEndPoint.Address, interfaceIp);
socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, option);
//bind on a network interface
socket.Bind(interfaceEndPoint);
//initialize args for sending packet on the multicast channel
var sockArgs = new SocketAsyncEventArgs();
sockArgs.RemoteEndPoint = multicastEndPoint;
sockArgs.SetBuffer(new byte[1234], 0, 1234);
//send an empty packet of size 1234 every 3 seconds
while (true)
{
socket.SendToAsync(sockArgs);
Thread.Sleep(3000);
}
}

Socket connection in CF 3.5 C#

I am trying to establish a communication between a handheld and a PC.
I have the following code, for the client:
public void connect(string IPAddress, int port)
{
// Connect to a remote device.
try
{
IPAddress ipAddress = new IPAddress(new byte[] { 192, 168, 1, 10 });
IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);
// Create a TCP/IP socket.
client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
// Connect to the remote endpoint.
client.BeginConnect(remoteEP, new AsyncCallback(ConnectCallback), client);
if (connectDone.WaitOne()){
//do something..
}
else{
MessageBox.Show("TIMEOUT on WaitOne");
}
}
catch(Exception e){
MessageBox.Show(e.Message);
}
}
My problem is that when I run both of them in a pc they communicate fine, but the same code in a SmartDevice Project doesn't connect with the Server which is running on the PC and it give me this error:
System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or stablished connection failed
because connected host has failed to respond
What am I missing?
NOTE: The IPAddress is hard coded inside the code
EDIT: here is another code which I take from a MSDN example. This don't work either, it says that it not possible to read. The server code in this case is the same as the example, the client code have a modification:
private void button1_Click(object sender, EventArgs e)
{
// In this code example, use a hard-coded
// IP address and message.
string serverIP = "192.168.1.10";//HERE IS THE DIFERENCE
string message = "Hello";
Connect(serverIP, message);
}
Thanks in advance for any help!

For my "mobile device" client, I send data to the "PC" host using this:
private void Send(string value) {
byte[] data = Encoding.ASCII.GetBytes(value);
try {
using (TcpClient client = new TcpClient(txtIPAddress.Text, 8000)) {
NetworkStream stream = client.GetStream();
stream.Write(data, 0, data.Length);
}
} catch (Exception err) {
// Log the error
}
}
For the host, you're best to use a thread or BackgroundWorker where you can let a TcpListener object sit and wait:
private void Worker_TcpListener(object sender, DoWorkEventArgs e) {
BackgroundWorker worker = (BackgroundWorker)sender;
do {
string eMsg = null;
int port = 8000;
try {
_listener = new TcpListener(IPAddress.Any, port);
_listener.Start();
TcpClient client = _listener.AcceptTcpClient(); // waits until data is avaiable
int MAX = client.ReceiveBufferSize;
NetworkStream stream = client.GetStream();
Byte[] buffer = new Byte[MAX];
int len = stream.Read(buffer, 0, MAX);
if (0 < len) {
string data = Encoding.UTF8.GetString(buffer);
worker.ReportProgress(len, data.Substring(0, len));
}
stream.Close();
client.Close();
} catch (Exception err) {
// Log your error
}
if (!String.IsNullOrEmpty(eMsg)) {
worker.ReportProgress(0, eMsg);
}
} while (!worker.CancellationPending);
}