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.
Related
I have a networking socket program in C#.net.
I have to connect with an ip: 169.254.74.65 and port:7998 and my ip is:169.254.74.63.
So I have this code:
using System;
using System.Net;
using System.Net.Sockets;
class MyTcpListener{
public static void Main(){
TcpListener server = null;
try{
Int32 port = 7998;
IPAddress localAddr = IPAddress.Parse("169.254.74.65");
server = new TcpListener(localAddr, port);
server.Start();
Byte[] bytes = new Byte[500];
String data = null;
while (true){
Console.Write("Waiting for a connection... ");
TcpClient client = server.AcceptTcpClient();
data = null;
NetworkStream stream = client.GetStream();
int i;
while ((i = stream.Read(bytes, 0, bytes.Length)) != 0){
data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
Console.WriteLine("Received: {0}", data);
}
client.Close();}
}
catch (SocketException e){
Console.WriteLine("SocketException: {0}", e);}
finally{ server.Stop(); }
Ping works fine between two IPs. Even telnet 169.254.74.65 7998 gives me proper result and listens to the correct messages. So the connection is solid.
But when I run the above code it shows an exception:
> SocketException: System.Net.Sockets.SocketException (0x80004005): The requested address is not valid in its context
at System.Net.Sockets.Socket.UpdateStatusAfterSocketErrorAndThrowException(SocketError error, String callerName)
at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketAddress)
at System.Net.Sockets.Socket.Bind(EndPoint localEP)
at System.Net.Sockets.TcpListener.Start(Int32 backlog)
at System.Net.Sockets.TcpListener.Start()
at MyTcpListener.Main() in C:\Users\Administrator\source\repos\TCPListener\TCPListener\Program.cs:line 12
What is the problem here?
Your code works for me:
Have you actually hit your server at 127.0.0.1:7998 from a client socket code?
Update
So your Server IP is 169.xx.xx.65, while your own DEV machine IP is 169.xx.xx.63
Your code is something which creates a TCP Server connection. While (if I am not wrong) - you only need to connect to that HL7 machine.
Understand that the HL7 machine will be the server and your machine will be the client. So you just need TcpClient. Something like:
TcpClient client = new TcpClient("169.xx.xx.65", 7998);
Use Connect/GetStream etc methods per: https://msdn.microsoft.com/en-us/library/system.net.sockets.tcpclient(v=vs.110).aspx
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 )
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.
Platform: Windows 2003 R2, C#
I have an application that sends UDP messages to other instances of itself, running on the same computer and on other computers. This is working fine. But, on some computers, the listener cannot hear messages that other thread/process on the same computer has transmitted. The message is broadcast ok, and other machines on the network hear the message, but a listener on the same machine cannot hear the message.
The weird part is that this happens on SOME machines in my test environment, but not all.
Edit: All machine that fail have the Check Point VPN-1 Securemote client software installed. I took a machine that was working, installed the VPN client, and now it does not work. Note that I am not connected to any VPN hosts, I just have the client installed.
All machines have a single network adapter, subnet mask of 255.255.255.0, and IP address of 10.3.10.xxx.
Here is a test class that demonstrates the problem. The user types some text, and it gets sent to 10.3.10.255. On some machines, the ReceiveFrom returns, and on others it does not. I am calling Controller("10.3.10.255",33333)
public class Controller
{
public Controller(IPAddress broadcastAddress, int port)
{
_broadcastAddress = broadcastAddress;
_port = port;
}
public void Start()
{
Socket s = null;
try
{
IPEndPoint _listenEndpoint = new IPEndPoint(IPAddress.Any, _port);
_broadcastEndpoint = new IPEndPoint(_broadcastAddress, _port);
s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
s.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastTimeToLive, 10);
s.EnableBroadcast = true;
s.Bind(_listenEndpoint);
SocketState receiveState = new SocketState();
receiveState.s = s;
receiveState.buf = new byte[1024];
EndPoint lep = (EndPoint)_broadcastEndpoint;
s.BeginReceiveFrom(receiveState.buf, 0, receiveState.buf.Length, SocketFlags.None, ref lep, new AsyncCallback(OnReceive), receiveState);
bool done = false;
while (!done)
{
string msg = Console.In.ReadLine();
byte[] msg_bytes = Encoding.ASCII.GetBytes(msg);
if (msg_bytes.Length == 0)
done = true;
else
{
Console.Out.WriteLine("---> {0}", msg);
s.SendTo(msg_bytes, msg_bytes.Length, SocketFlags.None, new IPEndPoint(_broadcastAddress, _port));
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
if (s != null)
s.Close();
}
}
internal void OnReceive(IAsyncResult ar)
{
SocketState state = ar.AsyncState as SocketState;
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 0);
EndPoint ep = (EndPoint)ipep;
int nRead = state.s.EndReceiveFrom(ar, ref ep);
IPEndPoint myipep = ep as IPEndPoint;
Console.WriteLine("<--- {0} {1}", myipep.Address.ToString(), System.Text.Encoding.ASCII.GetString(state.buf, 0, nRead));
EndPoint lep = (EndPoint)_broadcastEndpoint;
state.s.BeginReceiveFrom(state.buf, 0, state.buf.Length, SocketFlags.None, ref lep, new AsyncCallback(OnReceive), state);
}
IPAddress _broadcastAddress;
int _port = 0;
IPEndPoint _broadcastEndpoint;
}
internal class SocketState
{
internal Socket s;
internal byte[] buf;
}
What does the Check Point VPN-1 Securemote client software do? It sounds like it might do some sort of firewalling in which case it would be blocking data coming in on the specified port.
1) If you can configure it to allow data through that port, then you should be good to go.
2) Another less likely option is that maybe it is listening on the port that you are trying to listen to in which case it is receiving the udp packet as opposed to your application. I would expect you app to throw an error though in that case.
In the SecureClient settings (right click on the tray icon and select Settings), on the Security tab you can enable an option to "log all connections that are blocked by the desktop security policy".
You should then be able to see if that's indeed what is blocking your application - if it is, you'll have to get the default policy changed to allow your application. I'm not sure how to do that - I've never administered the server side of SecureRemote, but I'm sure Check Point can help you out if your network admins can't.