I am trying to get a little client/server thing going just to learn how to do it... But after using many samples, following several tutorials even on msdn, none of them have ever worked.
I keep getting the following exception:
System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it 220.101.27.107:8000
at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
at System.Net.Sockets.Socket.Connect(EndPoint remoteEP)
at t.MainForm.toolStripButton1344_Click(Object sender, EventArgs e) in C:\Users\Jason\Documents\Visual Studio 2008\Projects\t\t\MainForm.cs:line 1648
and the code i have is:
private void toolStripButton1344_Click(object sender, EventArgs e)
{
String strHostName;
string ipaddy;
// Getting Ip address of local machine...
// First get the host name of local machine.
strHostName = Dns.GetHostName();
Console.WriteLine("Local Machine's Host Name: " + strHostName);
// Then using host name, get the IP address list..
IPHostEntry ipEntry = Dns.GetHostByName(strHostName);
IPAddress[] addr = ipEntry.AddressList;
for (int i = 0; i < addr.Length; i++)
{
ipaddy = addr[i].ToString();
}
Socket st = new Socket(
AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
IPEndPoint ipe = new IPEndPoint(addr[0], 8000);
try
{
st.Connect(ipe);
}
catch (ArgumentNullException ae)
{
MessageBox.Show("ArgumentNullException : {0}" + ae.ToString());
}
catch (SocketException se)
{
MessageBox.Show("SocketException : {0}" + se.ToString());
}
catch (Exception ex)
{
MessageBox.Show("Unexpected exception : {0}" + ex.ToString());
}
}
Can someone please help me understand why this won't work??
Thank you :)
Have you started the server, before trying to connect with the client?
Also, make sure that the port you are using (8000) isn't blocked by a firewall or occupied by another process.
Basically, the error message says the target machine (the one you're trying to connect to) answered the SYN (connection request packet) with an RST (reset, i.e. no connection possible in this case). What it means is, there's no server process listening on the other end.
Client-server software comes in two parts, the client which is connecting to the second part, the server. The server process needs to be listening on a tcp port in order to accept connections, and the client must connect to the servers IP address, along with the port it's listening on.
Well, if all you are trying to do is test creating a socket connection, use "google.com" as your host name and 80 as your port. That is guaranteed to always be listening. And if it's not, then, well, that would probably mean that the world has stopped.
I figured out why it wasn't working. Recently a little application (which I had no idea about) was installed along with a program that I chose to install, and that app was using up several ports. I've managed to get rid of that app, and everything's working just fine :)
Thank you all for your help and suggestions!
Related
I would start TcpListener server with my global IP address.
I have open ports and using DMZ and my port 8074 is available and i should be able to start this server.
My code looks like :
IPAddress ip = IPAddress.Parse("XX.XXX.XX.XXX.XX");
TcpListener server = new TcpListener(ip, Convert.ToInt32(8888));
TcpClient client = default(TcpClient);
try
{
server.Start();
Console.WriteLine("Server started...");
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
};
And all the time i have Error looks like:
Activated Event Time Duration Thread Exception: An exception was
thrown: "System.Net.Sockets.SocketException" in System.dll ("The
requested address is different in this context"). An exception was
thrown: "System.Net.Sockets.SocketException" in System.dll ("The
requested address is different in this context") 5.52s [5780] Worker
thread
You can check if you want this port is accessible on my IP address but can't start server on this.
Yeah thanks #jdweng .
All i need to change was just this lane :
IPAddress ip = IPAddress.Any;
It was my expectation that, if the endpoint is not available, the UdpClient.Connect() method would throw an exception that I could capture and, say, alter a label's text to say if the program was connected to the server or not. However, despite me having turned off the server that I'm trying to connect to, the method completes with no issue. Is there some way to resolve this issue, or some other method I should be attempting?
My current code (IP address blanked out, but is valid):
UdpClient chatConnection = new UdpClient();
IPEndPoint serverEndPoint = new IPEndPoint(IPAddress.Parse("xxx.xx.xxx.xxx"), 1000);
// Initialize client/server connection and set status text
try
{
chatConnection.Connect(serverEndPoint);
SL_Status.Text = "Connected";
}
catch (Exception ex)
{
SL_Status.Text = "Not Connected";
MessageBox.Show("Unable to connect to server. See console for logs.");
Console.WriteLine(ex);
}
Since UDP is connectionless checking if client is connected doesn't apply to it.
There is however a workaround that in some cases may work:
answer by Yahia
catch (SocketException se)
{
if(se.ErrorCode == 10054 || se.ErrorCode == 10053) // Error code for Connection reset by peer
{
Console.WriteLine("User from " + currentSocket.RemoteEndPoint.ToString() + " timed out");
}
}
I have a problem with socket exception with mono, above code runs perfectly on windows, while on mono throws exception that RemoteEndPoint is null.
My question is how to obtain ip address of disconnected user using mono?
Create a wrapper which holds the socket and any additional information you need. Upon connection, you can populate the values you want to save such as their ip address. When a disconnect occurs, you can log from this variable instead of off the socket object.
So I'm all new to this 'Socket' programming and there seems to be something I have fundamentally misunderstood ...
The documentation for the server I use is very poorly written, but says it uses a "streaming socket connection" that is "event based" ... the server is on the local network.
here is my first naive program flow (no async or anything!):
.........
1) First I need a Socket ... no problem ... I get that :)
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
2) Then I connect with it ... also no problem :)
s.Connect("10.10.10.36", 6009);
3) Now that I have my connection and I have the new local EP given by the server ... something like "10.10.10.59:56231" ... so I try to Bind to that EP :
s.Bind (s.LocalEndPoint);
After that I need to listen and begin accepting connections :
s.Listen (10);
s.Accept ();
.........
the "s.Bind (s.LocalEndPoint);" fails (I ran it without the debugger) with this :
.........
Unhandled Exception:
System.Net.Sockets.SocketException: Invalid arguments
at System.Net.Sockets.Socket.Bind (System.Net.EndPoint local_end) [0x00065] in /private/tmp/source/bockbuild-xamarin/profiles/mono-mac-xamarin-no-pcl/build-root/mono-3.2.0/mcs/class/System/System.Net.Sockets/Socket.cs:1115
at RFID.MainClass.Main (System.String[] args) [0x0002b] in /Users/jab/Projects/RFID/RFID/Program.cs:17
[ERROR] FATAL UNHANDLED EXCEPTION: System.Net.Sockets.SocketException: Invalid arguments
at System.Net.Sockets.Socket.Bind (System.Net.EndPoint local_end) [0x00065] in /private/tmp/source/bockbuild-xamarin/profiles/mono-mac-xamarin-no-pcl/build-root/mono-3.2.0/mcs/class/System/System.Net.Sockets/Socket.cs:1115
at RFID.MainClass.Main (System.String[] args) [0x0002b] in /Users/jab/Projects/RFID/RFID/Program.cs:17
.........
Now I know this is very primitive question but I need to be pointed in the right direction :)
TIA.
The problem occurs because you connectthe socket. But you would only connect the client (not the server). To get a local endpoint to listen on, just create one yourself :
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 6009);
s.Bind (localEndPoint);
After this it should work.
The reason why bind() would not work for a client is because the connect() implicitly binds the client socket to a temporary port number. But, if you try to bind() before connect(), then it would succeed. So, for client side, all you need to do is open a socket and connect. For the server side, you would need to open a socket, bind it to a port, start listening, and then get pending connections using accept().
I was trying to run a .Net socket server code on Win7-64bit machine .
I keep getting the following error:
System.Net.Sockets.SocketException: An address incompatible with the requested protocol
was used.
Error Code: 10047
The code snippet is :
IPAddress ipAddress = Dns.GetHostEntry("localhost").AddressList[0];
IPEndPoint ip = new IPEndPoint(ipAddress, 9989);
Socket serverSocket = new Socket(AddressFamily.InterNetwork,SocketType.Stream, ProtocolType.Tcp);
try
{
serverSocket.Bind(ip);
serverSocket.Listen(10);
serverSocket.BeginAccept(new AsyncCallback(AcceptConn), serverSocket);
}
catch (SocketException excep)
{
Log("Native code:"+excep.NativeErrorCode);
// throw;
}
The above code works fine in Win-XP sp3 .
I have checked Error code details on MSDN but it doesn't make much sense to me.
Anyone has encountered similar problems? Any help?
On Windows Vista (and Windows 7), Dns.GetHostEntry also returns IPv6 addresses. In your case, the IPv6 address (::1) is first in the list.
You cannot connect to an IPv6 (InterNetworkV6) address with an IPv4 (InterNetwork) socket.
Change your code to create the socket to use the address family of the specified IP address:
Socket serverSocket =
new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
↑
Note: There's a shortcut to obtain the IP address of localhost: You can simply use IPAddress.Loopback (127.0.0.1) or IPAddress.IPv6Loopback (::1).
Edit C:\Windows\System32\drivers\etc\hosts and add the line "127.0.0.1 localhost" (if its not there, excluding quotes)