How to check if TcpClient Connection is closed?

by

I wouldn’t recommend you to try write just for testing the socket. And don’t relay on .NET’s Connected property either.

If you want to know if the remote end point is still active, you can use TcpConnectionInformation:

TcpClient client = new TcpClient(host, port);

IPGlobalProperties ipProperties = IPGlobalProperties.GetIPGlobalProperties();
TcpConnectionInformation[] tcpConnections = ipProperties.GetActiveTcpConnections().Where(x => x.LocalEndPoint.Equals(client.Client.LocalEndPoint) && x.RemoteEndPoint.Equals(client.Client.RemoteEndPoint)).ToArray();

if (tcpConnections != null && tcpConnections.Length > 0)
{
    TcpState stateOfConnection = tcpConnections.First().State;
    if (stateOfConnection == TcpState.Established)
    {
        // Connection is OK
    }
    else 
    {
        // No active tcp Connection to hostName:port
    }

}
client.Close();

See Also:
TcpConnectionInformation on MSDN
IPGlobalProperties on MSDN
Description of TcpState states
Netstat on Wikipedia

And here it is as an extension method on TcpClient.

public static TcpState GetState(this TcpClient tcpClient)
{
  var foo = IPGlobalProperties.GetIPGlobalProperties()
    .GetActiveTcpConnections()
    .SingleOrDefault(x => x.LocalEndPoint.Equals(tcpClient.Client.LocalEndPoint));
  return foo != null ? foo.State : TcpState.Unknown;
}

More Related Contents:

  1. What are some reasons NetworkStream.Read would hang/block?
  2. What is the correct way to read from NetworkStream in .NET
  3. How to get all data from NetworkStream
  4. Get Length of Data Available in NetworkStream
  5. Conecting TCP client (on linux/c++) to TCP server (on windows c#) [duplicate]
  6. Programming P2P application
  7. How to configure socket connect timeout
  8. Using .Net 4.5 Async Feature for Socket Programming
  9. How to set the timeout for a TcpClient?
  10. C# TcpClient: Send serialized objects using separators?
  11. An attempt was made to access a socket in a way forbidden by its access permissions. Why?
  12. GPS Socket communication (CONCOX)
  13. Async lock not allowed
  14. Sending and receiving data over a network using TcpClient
  15. Broken TCP messages
  16. Can a TCP c# client receive and send continuously/consecutively without sleep?
  17. Sending a value from server to client with sockets
  18. C# Begin/EndReceive – how do I read large data?
  19. Unity: Live Video Streaming
  20. Streaming input to System.Speech.Recognition.SpeechRecognitionEngine
  21. Proper way to stop TcpListener
  22. Communicating with a socket.io server via c#
  23. “An operation on a socket could not be performed because the system lacked sufficient buffer space or because a queue was full”
  24. Getting the location from a WebClient on a HTTP 302 Redirect?
  25. Sockets On Same Machine For Windows and Linux
  26. C# Stream.Read with timeout
  27. How can I get all the active TCP connections using .NET Framework (no unmanaged PE import!)?
  28. How do I obtain the latency between server and client in C#?
  29. Marshal.PtrToStructure (and back again) and generic solution for endianness swapping
  30. “A connection attempt failed because the connected party did not properly respond after a period of time” using WebClient

Leave a Comment