TcpState TcpState TcpState TcpState Enum

Definition

Specifies the states of a Transmission Control Protocol (TCP) connection.

public enum class TcpState
public enum TcpState
type TcpState = 
Public Enum TcpState
Inheritance

Fields

Closed Closed Closed Closed 1

The TCP connection is closed.

CloseWait CloseWait CloseWait CloseWait 8

The local endpoint of the TCP connection is waiting for a connection termination request from the local user.

Closing Closing Closing Closing 9

The local endpoint of the TCP connection is waiting for an acknowledgement of the connection termination request sent previously.

DeleteTcb DeleteTcb DeleteTcb DeleteTcb 12

The transmission control buffer (TCB) for the TCP connection is being deleted.

Established Established Established Established 5

The TCP handshake is complete. The connection has been established and data can be sent.

FinWait1 FinWait1 FinWait1 FinWait1 6

The local endpoint of the TCP connection is waiting for a connection termination request from the remote endpoint or for an acknowledgement of the connection termination request sent previously.

FinWait2 FinWait2 FinWait2 FinWait2 7

The local endpoint of the TCP connection is waiting for a connection termination request from the remote endpoint.

LastAck LastAck LastAck LastAck 10

The local endpoint of the TCP connection is waiting for the final acknowledgement of the connection termination request sent previously.

Listen Listen Listen Listen 2

The local endpoint of the TCP connection is listening for a connection request from any remote endpoint.

SynReceived SynReceived SynReceived SynReceived 4

The local endpoint of the TCP connection has sent and received a connection request and is waiting for an acknowledgment.

SynSent SynSent SynSent SynSent 3

The local endpoint of the TCP connection has sent the remote endpoint a segment header with the synchronize (SYN) control bit set and is waiting for a matching connection request.

TimeWait TimeWait TimeWait TimeWait 11

The local endpoint of the TCP connection is waiting for enough time to pass to ensure that the remote endpoint received the acknowledgement of its connection termination request.

Unknown Unknown Unknown Unknown 0

The TCP connection state is unknown.

Examples

The following code example counts the established TCP connections.

void CountTcpConnections()
{
   IPGlobalProperties ^ properties = IPGlobalProperties::GetIPGlobalProperties();
   array<TcpConnectionInformation^>^connections = properties->GetActiveTcpConnections();
   int establishedConnections = 0;
   System::Collections::IEnumerator^ myEnum1 = connections->GetEnumerator();
   while ( myEnum1->MoveNext() )
   {
      TcpConnectionInformation ^ t = safe_cast<TcpConnectionInformation ^>(myEnum1->Current);
      if ( t->State == TcpState::Established )
      {
         establishedConnections++;
      }

      Console::Write( "Local endpoint: {0} ", t->LocalEndPoint->Address );
      Console::WriteLine( "Remote endpoint: {0} ", t->RemoteEndPoint->Address );
   }

   Console::WriteLine( "There are {0} established TCP connections.", establishedConnections );
}
public static void CountTcpConnections()
{
    IPGlobalProperties properties = IPGlobalProperties.GetIPGlobalProperties();
    TcpConnectionInformation[] connections = properties.GetActiveTcpConnections();
    int establishedConnections = 0;
    
    foreach (TcpConnectionInformation t in connections)
    {
        if (t.State == TcpState.Established)
        {
             establishedConnections++;
        }
        Console.Write("Local endpoint: {0} ",t.LocalEndPoint.Address);
        Console.WriteLine("Remote endpoint: {0} ",t.RemoteEndPoint.Address);
       
    }
     Console.WriteLine("There are {0} established TCP connections.",
        establishedConnections);
}
Public Shared Sub CountTcpConnections() 
    Dim properties As IPGlobalProperties = IPGlobalProperties.GetIPGlobalProperties()
    Dim connections As TcpConnectionInformation() = properties.GetActiveTcpConnections()
    Dim establishedConnections As Integer = 0
    
    Dim t As TcpConnectionInformation
    For Each t In  connections
        If t.State = TcpState.Established Then
            establishedConnections += 1
        End If
        Console.Write("Local endpoint: {0} ", t.LocalEndPoint.Address)
        Console.WriteLine("Remote endpoint: {0} ", t.RemoteEndPoint.Address)
    Next t 
    Console.WriteLine("There are {0} established TCP connections.", establishedConnections)

End Sub

Remarks

This enumeration defines valid values for the State property. TCP is a transport layer protocol responsible for reliably sending and receiving data packets. The TCP states in this enumeration are defined in IETF RFC 793 available at https://www.ietf.org.

Applies to