I'm trying to implement Hole punching using C# but unfortunately I spent hours to figure out why it doesn't work for me. Here is my problem:
I have a third part server that I can manage all external IPs for the peers on, and of course my router is behind a NAT, and I assume all my peers are also behind NATs.
Say if I managed to figure out all slaves (peers), End points (external ips). Where to put the external ip address of my server which runs on my pc (not the third party one), and where to put the peer ip address?
This is my code:
public void HolePunch(String ServerIp, Int32 Port) // if I put my external ip here I get Exception (An address incompatible with the requested protocol was used)
{
IPEndPoint LocalPt = new IPEndPoint(Dns.GetHostEntry(Dns.GetHostName()).AddressList[0], Port);
UdpClient Client = new UdpClient();
Client.ExclusiveAddressUse = false;
Client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
Client.Client.Bind(LocalPt);
IPEndPoint RemotePt = new IPEndPoint(IPAddress.Parse(ServerIp), Port);
// This Part Sends your local endpoint to the server so if the two peers are on the same nat they can bypass it, you can omit this if you wish to just use the remote endpoint.
byte[] IPBuffer = System.Text.Encoding.UTF8.GetBytes(Dns.GetHostEntry(Dns.GetHostName()).AddressList[0].ToString());
byte[] LengthBuffer = BitConverter.GetBytes(IPBuffer.Length);
byte[] PortBuffer = BitConverter.GetBytes(Port);
byte[] Buffer = new byte[IPBuffer.Length + LengthBuffer.Length + PortBuffer.Length];
LengthBuffer.CopyTo(Buffer,0);
IPBuffer.CopyTo(Buffer, LengthBuffer.Length);
PortBuffer.CopyTo(Buffer, IPBuffer.Length + LengthBuffer.Length);
Client.BeginSend(Buffer, Buffer.Length, RemotePt, new AsyncCallback(SendCallback), Client);
// Wait to receve something
BeginReceive(Client, Port);
// you may want to use a auto or manual ResetEvent here and have the server send back a confirmation, the server should have now stored your local (you sent it) and remote endpoint.
// you now need to work out who you need to connect to then ask the server for there remote and local end point then need to try to connect to the local first then the remote.
// if the server knows who you need to connect to you could just have it send you the endpoints as the confirmation.
// you may also need to keep this open with a keepalive packet untill it is time to connect to the peer or peers.
// once you have the endpoints of the peer you can close this connection unless you need to keep asking the server for other endpoints
Client.Close();
}
public void ConnectToPeer(String PeerIp, Int32 Port)
{
IPEndPoint LocalPt = new IPEndPoint(Dns.GetHostEntry(Dns.GetHostName()).AddressList[0], Port);
UdpClient Client = new UdpClient();
Client.ExclusiveAddressUse = false;
Client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
Client.Client.Bind(LocalPt);
IPEndPoint RemotePt = new IPEndPoint(IPAddress.Parse(PeerIp), Port);
Client.Connect(RemotePt);
//you may want to keep the peer client connections in a list.
BeginReceive(Client, Port);
}
public void SendCallback(IAsyncResult ar)
{
UdpClient Client = (UdpClient)ar.AsyncState;
Client.EndSend(ar);
}
public void BeginReceive(UdpClient Client, Int32 Port)
{
IPEndPoint ListenPt = new IPEndPoint(IPAddress.Any, Port);
Object[] State = new Object[] { Client, ListenPt };
Client.BeginReceive(new AsyncCallback(ReceiveCallback), State);
}
public void ReceiveCallback(IAsyncResult ar)
{
UdpClient Client = (UdpClient)((Object[])ar.AsyncState)[0];
IPEndPoint ListenPt = (IPEndPoint)((Object[])ar.AsyncState)[0];
Byte[] receiveBytes = Client.EndReceive(ar, ref ListenPt);
}
EDIT :
the code works will if I give it my local ip and if my clients in my pc .. but if I supply it an external ip it doesn't work ( the exception in the first line comment )
Related
I am having trouble with my c# tcp code.
When I run the server and the client on the same computer, it will connect just fine.
But when I run the client on a different PC or on a phone, I get: 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.
Here is the server code:
private static void CreateServer()
{
TcpListener server = null;
try
{
Int32 port = 13000;
IPAddress localAddr = IPAddress.Parse("127.0.0.1");
server = new TcpListener(localAddr, port);
server.Start();
Byte[] bytes = new Byte[256];
String data = null;
while (true)
{
Console.Write("Waiting for a connection... ");
/*
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
var ipAddress = ipHostInfo.AddressList;
Console.WriteLine(ipHostInfo.HostName);
Console.WriteLine(ipAddress[0]);
*/
TcpClient client = server.AcceptTcpClient();
Console.WriteLine("Connected!");
data = null;
NetworkStream stream = client.GetStream();
int i;
try
{
while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
{
data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
Console.WriteLine("Received: {0}", data);
data = data.ToUpper();
byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);
stream.Write(msg, 0, msg.Length);
}
}
catch(IOException e)
{
//Console.WriteLine(e);
Console.WriteLine("Restarting Server");
//client.Close();
//CreateServer();
}
// Shutdown and end connection
client.Close();
}
}
catch (SocketException e)
{
//Console.WriteLine("SocketException: {0}", e);
}
finally
{
// Stop listening for new clients.
server.Stop();
}
Console.WriteLine("\nHit enter to continue...");
Console.Read();
}
I removed most of the comments. But that is the basic example for a tcp server from the documentation.
the client connect code is very simple:
tcpClient = new TcpClient();
tcpClient.Connect("192.168.0.7", 13000);
with the declaration for tcpClient saved in a less local spot for retaining and quickly reconnecting.
What I have tried:
I have made sure the IP address is correct, I even port forwarded and used my external IP, but got the same issue.
I made sure the firewall is not blocking the app on either device.
I tried using either device as the server.
I've looked up the problem and the only other person to have this issue needed to make sure he put in the correct IP and fix his firewall settings. I'm probably missing something super obvious.
One final piece of information, one device is wired to the router, I don't know if that is messing with anything.
One other thing, I tried:
tcpClient.Connect(new IPEndPoint(IPAddress.Parse("192.168.0.7"), 13000));
as well.
Whelp I was right. It was something very obvious and honestly dumb on my part.
on the server side:
IPAddress localAddr = IPAddress.Parse("127.0.0.1");
does not result in the server listening on its ipv4, instead it listens on an ipv6
so what you want:
Remove the localAddr declaration, as it is not important, and instead of calling:
server = new TcpListener(localAddr, port);
call:
server = new TcpListener(IPAddress.Any, port);
IPAddress.Any is used to listen across all of the network interfaces the device has.
I've made a simple chat application in c#.net that sends and receives data between 2 computers.
So, I used this method to send the data:
int port = 11000;
private void send(string data, string ip)
{
Socket sending_socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPEndPoint sending_end_point = null;
byte[] send_buffer = Encoding.ASCII.GetBytes(data);
sending_end_point = new IPEndPoint(IPAddress.Parse(ip), port);
try { sending_socket.SendTo(send_buffer, sending_end_point); }
catch { }
}
And to receive I used this:
string receiveddata = "";
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
UdpClient listener = new UdpClient(port);
IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, port);
byte[] receive_byte_array;
try
{
receive_byte_array = listener.Receive(ref groupEP);
receiveddata = Encoding.ASCII.GetString(receive_byte_array, 0, receive_byte_array.Length);
}
catch { }
listener.Close();
}
This works without any problems between 2 computers on a LAN, but I would like to know (if possible) how to do the same thing over the Internet.
From what I've searched on the Internet, it seems that I have to use port-forwarding in order to do that, so I already did that, but I don't know what should I do know.
So my question is, how should I change this code (if I have to) so I could send and receive data (UDP) over the internet, assuming I have port-forwarded correctly already and assuming I know the external IPs of both routers?
Thank you in advance.
This should work just fine, as long as your (public) IP-address is correct and the ports are forwarded correctly on your router (meaning, forwarded to the correct private IP, on the correct protocol, in your case UDP).
You are aware that this is UDP though, so it's not reliable data transfer.
For some reason the C# socket.RemoteEndPoint started returning the address of the default gateway. It used to work and I know the code hasn't changed. I'm not sure when it started occurring as the logs don't go back far enough so I'm not sure what could have happened to this server to cause this. Everything seems to be working normally. Just not getting the remote IP anymore.
Anyone have any idea what could cause this?
Here is the relevant code.
public void startClientListening(string ipString, int port)
{
IPAddress ip = IPAddress.Parse(ipString);
// Create the listening socket...
clientListenerSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPEndPoint ipLocal = new IPEndPoint(ip, port);
// Bind to local IP Address...
clientListenerSocket.Bind(ipLocal);
// Start listening...
clientListenerSocket.Listen(32);
// Create the call back for any client connections...
clientListenerSocket.BeginAccept(onClientConnect, clientListenerSocket);
}
private void onClientConnect(IAsyncResult asyn)
{
Socket workerSocket = clientListenerSocket.EndAccept(asyn);
workerSocket.NoDelay = true;
//This returns 192.168.1.1 rather than the remoteIp
string remoteIp = ((IPEndPoint)workerSocket.RemoteEndPoint).Address.ToString();
}
This could happen if the default gateway was a router/ip firewall before but now it is a proxy/application firewall.
In this case the ip connection is instantiated by the proxy and therefore you see the ip address of the proxy and not of the real client.
I'm going to setup a small client/server server in TCP/IP mode, I use VS2010,C# to develop my apps, I've googled a lot and could find some source codes, but none of them work in internet, I can get some answers in my own local system, i.e. I run my server, then listen for my own localhost (127.0.0.1) then send some data (for example using telnet), it works fine but when I do the same over internet I get nothing! I want to use port 80, as I want to send/receive http data, I have tested several source codes, here is the last code I have used (and it works on localhost with telnet)
//server code:
form_load()
IPAddress localAddress = IPAddress.Parse("127.0.0.1");
Socket listenSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPEndPoint ipEndpoint = new IPEndPoint(localAddress, 80);
// Bind the socket to the end point
listenSocket.Bind(ipEndpoint);
// Start listening, only allow 1 connection to queue at the same time
listenSocket.Listen(1);
listenSocket.BeginAccept(new AsyncCallback(ReceiveCallback), listenSocket);
Console.WriteLine("Server is waiting on socket {0}", listenSocket.LocalEndPoint);
// Start being important while the world rotates
while (true)
{
Console.WriteLine("Busy Waiting....");
Thread.Sleep(2000);
}
public static void ReceiveCallback(IAsyncResult AsyncCall)
{
System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();
Byte[] message = encoding.GetBytes("I am a little busy, come back later!");
Socket listener = (Socket)AsyncCall.AsyncState;
Socket client = listener.EndAccept(AsyncCall);
Console.WriteLine("Received Connection from {0}", client.RemoteEndPoint);
client.Send(message);
Console.WriteLine("Ending the connection");
client.Close();
listener.BeginAccept(new AsyncCallback(ReceiveCallback), listener);
}
send data (client), of course I haven't used this code, is it right?
public static string SendData()
{
TcpClient client = new TcpClient();
client.Connect(IP, 80);
StreamWriter sw = new StreamWriter(client.GetStream());
StreamReader sr = new StreamReader(client.GetStream());
//if statement evalutes to see if the user has selected to update the server
//" " = update server
//"" = do not update the server
//if (updateData.Equals(""))
//{
// space = "";
//}
//else if (!updateData.Equals(""))
//{
// space = " ";
//}
//Refrences stream writer, username variable passed in from GUI
//space variable provides update function: "" = dont update. " " = update database.
sw.WriteLine("h");
sw.Flush();
//data send back from the server assigned to string variable
//string recieved = sr.ReadLine();
return "";
}
I'm going to have the server code in my Server (winserver 2008R2) but currently test it in normal PCs, what am I doing wrong? I want to send some http packet from a random system (with a random IP) to my server (which I know its IP), what should I do? is it possible with tcp/ip or I should do something else?
is it related to static IP? should I certainly have static IP? my web server has a static IP but my clients do not, is it a problem?
I think I have some problem in defining ports and IPs, how should I set them? my server has a specific IP, but I don't know IP of my clients, would you please explain it to me step by step?
thanks
The two most common problems in this scenario:
Ensure your server's router is using port forwarding to forward HTTP requests from the router to the server.
Ensure you are connecting to the server's public IP address, not its local network address.
I created an application with server and client tool using sockets etc. When using my code on my computer works. Now I installed the Himachi software and I need to use this software in my application so that when a user connects with me, the application created could be used in this network. Note that this is my first time using sockets. The problem is that they are not connecting to each other and also it gives me this error on changing the ip and port: The requested address is not valid in its context
The send Tool
public Send(string Group, string port, string ttl, string rep, string data)
{
IPAddress ip;
try
{
Console.WriteLine("Send on Group: {0} Port: {1} TTL: {2}", Group,port,ttl);
ip = IPAddress.Parse(Group);
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
s.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, new MulticastOption(ip));
s.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastTimeToLive, int.Parse(ttl));
IPEndPoint ipep = new IPEndPoint(IPAddress.Parse(Group),int.Parse(port));
Console.WriteLine("Connecting...");
s.Connect(ipep);
byte[] byData = System.Text.Encoding.ASCII.GetBytes(data);
s.Send(byData, SocketFlags.None);
Console.WriteLine("Closing Connection...");
s.Close();
}
catch(System.Exception e) { Console.Error.WriteLine(e.Message); }
}
The Receive tool
public string RecvData(string Group, string port)
{
string str = "";
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, int.Parse(port));
s.Bind(ipep);
IPAddress ip = IPAddress.Parse(Group);
s.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, new MulticastOption(ip,IPAddress.Any));
// Getting the data
byte[] buffer = new byte[1024];
int iRx = s.Receive(buffer);
str = System.Text.Encoding.ASCII.GetString(buffer, 0, buffer.Length);
// Closing a Socket
s.Close();
return str;
}
Thanks
So your problem is that you are trying to use a VPN (hamachi) to connect two apps the server and the client so that the client can receive messages from the server right? I think that the error given "The requested address is not valid in its context" is because you are using a VPN but I don't know how this can be solved sorry. What I think is that maybe you might also need the network id and password but again I'm not sure. Please keep us informed because this is a very interesting question.