TcpListener Class

Definition

Namespace:

System.Net.Sockets

Assembly:

System.Net.Sockets.dll

Source:

TCPListener.cs

Listens for connections from TCP network clients.

public ref class TcpListener : IDisposable

public class TcpListener : IDisposable

type TcpListener = class
    interface IDisposable

Public Class TcpListener
Implements IDisposable

Inheritance

Object

TcpListener

Implements

IDisposable

Examples

The following code example creates a TcpListener.

#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Net;
using namespace System::Net::Sockets;
using namespace System::Text;
using namespace System::Threading;
void main()
{
   try
   {
      
      // Set the TcpListener on port 13000.
      Int32 port = 13000;
      IPAddress^ localAddr = IPAddress::Parse( "127.0.0.1" );
      
      // TcpListener* server = new TcpListener(port);
      TcpListener^ server = gcnew TcpListener( localAddr,port );
      
      // Start listening for client requests.
      server->Start();
      
      // Buffer for reading data
      array<Byte>^bytes = gcnew array<Byte>(256);
      String^ data = nullptr;
      
      // Enter the listening loop.
      while ( true )
      {
         Console::Write( "Waiting for a connection... " );
         
         // Perform a blocking call to accept requests.
         // You could also use server.AcceptSocket() here.
         TcpClient^ client = server->AcceptTcpClient();
         Console::WriteLine( "Connected!" );
         data = nullptr;
         
         // Get a stream Object* for reading and writing
         NetworkStream^ stream = client->GetStream();
         Int32 i;
         
         // Loop to receive all the data sent by the client.
         while ( i = stream->Read( bytes, 0, bytes->Length ) )
         {
            
            // Translate data bytes to a ASCII String*.
            data = Text::Encoding::ASCII->GetString( bytes, 0, i );
            Console::WriteLine( "Received: {0}", data );
            
            // Process the data sent by the client.
            data = data->ToUpper();
            array<Byte>^msg = Text::Encoding::ASCII->GetBytes( data );
            
            // Send back a response.
            stream->Write( msg, 0, msg->Length );
            Console::WriteLine( "Sent: {0}", data );
         }
         
         // Shutdown and end connection
         client->Close();
      }
   }
   catch ( SocketException^ e ) 
   {
      Console::WriteLine( "SocketException: {0}", e );
   }

   Console::WriteLine( "\nHit enter to continue..." );
   Console::Read();
}

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;

class MyTcpListener
{
  public static void Main()
  {
    TcpListener server = null;
    try
    {
      // Set the TcpListener on port 13000.
      Int32 port = 13000;
      IPAddress localAddr = IPAddress.Parse("127.0.0.1");

      // TcpListener server = new TcpListener(port);
      server = new TcpListener(localAddr, port);

      // Start listening for client requests.
      server.Start();

      // Buffer for reading data
      Byte[] bytes = new Byte[256];
      String data = null;

      // Enter the listening loop.
      while(true)
      {
        Console.Write("Waiting for a connection... ");

        // Perform a blocking call to accept requests.
        // You could also use server.AcceptSocket() here.
        using TcpClient client = server.AcceptTcpClient();
        Console.WriteLine("Connected!");

        data = null;

        // Get a stream object for reading and writing
        NetworkStream stream = client.GetStream();

        int i;

        // Loop to receive all the data sent by the client.
        while((i = stream.Read(bytes, 0, bytes.Length))!=0)
        {
          // Translate data bytes to a ASCII string.
          data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
          Console.WriteLine("Received: {0}", data);

          // Process the data sent by the client.
          data = data.ToUpper();

          byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);

          // Send back a response.
          stream.Write(msg, 0, msg.Length);
          Console.WriteLine("Sent: {0}", data);
        }
      }
    }
    catch(SocketException e)
    {
      Console.WriteLine("SocketException: {0}", e);
    }
    finally
    {
      server.Stop();
    }

    Console.WriteLine("\nHit enter to continue...");
    Console.Read();
  }
}

Imports System.IO
Imports System.Net
Imports System.Net.Sockets
Imports System.Text

Class MyTcpListener

    Public Shared Sub Main()

    Dim server As TcpListener
    server=nothing
        Try
            ' Set the TcpListener on port 13000.
         Dim port As Int32 = 13000
         Dim localAddr As IPAddress = IPAddress.Parse("127.0.0.1")

         server = New TcpListener(localAddr, port)
         
         ' Start listening for client requests.
         server.Start()
         
         ' Buffer for reading data
            Dim bytes(1024) As Byte
            Dim data As String = Nothing
         
         ' Enter the listening loop.
         While True
            Console.Write("Waiting for a connection... ")
            
            ' Perform a blocking call to accept requests.
            ' You could also use server.AcceptSocket() here.
            Dim client As TcpClient = server.AcceptTcpClient()
            Console.WriteLine("Connected!")
            
            data = Nothing
            
            ' Get a stream object for reading and writing
            Dim stream As NetworkStream = client.GetStream()
            
            Dim i As Int32
            
            ' Loop to receive all the data sent by the client.
            i = stream.Read(bytes, 0, bytes.Length)
            While (i <> 0) 
               ' Translate data bytes to a ASCII string.
               data = System.Text.Encoding.ASCII.GetString(bytes, 0, i)
                    Console.WriteLine("Received: {0}", data)
               
               ' Process the data sent by the client.
               data = data.ToUpper()
                    Dim msg As Byte() = System.Text.Encoding.ASCII.GetBytes(data)
               
               ' Send back a response.
               stream.Write(msg, 0, msg.Length)
                    Console.WriteLine("Sent: {0}", data)
              
               i = stream.Read(bytes, 0, bytes.Length)

            End While
            
            ' Shutdown and end connection
            client.Close()
         End While
      Catch e As SocketException
         Console.WriteLine("SocketException: {0}", e)
      Finally
         server.Stop()
      End Try
      
      Console.WriteLine(ControlChars.Cr + "Hit enter to continue....")
      Console.Read()
   End Sub

End Class

See TcpClient for a client example.

Remarks

The TcpListener class provides simple methods that listen for and accept incoming connection requests in blocking synchronous mode. You can use either a TcpClient or a Socket to connect with a TcpListener. Create a TcpListener using an IPEndPoint, a Local IP address and port number, or just a port number. Specify Any for the local IP address and 0 for the local port number if you want the underlying service provider to assign those values for you. If you choose to do this, you can use the LocalEndpoint property to identify the assigned information, after the socket has connected.

Use the Start method to begin listening for incoming connection requests. Start will queue incoming connections until you either call the Stop method or it has queued MaxConnections. Use either AcceptSocket or AcceptTcpClient to pull a connection from the incoming connection request queue. These two methods will block. If you want to avoid blocking, you can use the Pending method first to determine if connection requests are available in the queue.

Call the Stop method to close the TcpListener.

Note

The Stop method does not close any accepted connections. You are responsible for closing these separately.

Constructors

TcpListener(Int32)	Obsolete. Initializes a new instance of the TcpListener class that listens on the specified port.
TcpListener(IPAddress, Int32)	Initializes a new instance of the TcpListener class that listens for incoming connection attempts on the specified local IP address and port number.
TcpListener(IPEndPoint)	Initializes a new instance of the TcpListener class with the specified local endpoint.

Properties

Active	Gets a value that indicates whether TcpListener is actively listening for client connections.
ExclusiveAddressUse	Gets or sets a Boolean value that specifies whether the TcpListener allows only one underlying socket to listen to a specific port.
LocalEndpoint	Gets the underlying EndPoint of the current TcpListener.
Server	Gets the underlying network Socket.

Methods

AcceptSocket()	Accepts a pending connection request.
AcceptSocketAsync()	Accepts a pending connection request as an asynchronous operation.
AcceptSocketAsync(CancellationToken)	Accepts a pending connection request as a cancellable asynchronous operation.
AcceptTcpClient()	Accepts a pending connection request.
AcceptTcpClientAsync()	Accepts a pending connection request as an asynchronous operation.
AcceptTcpClientAsync(CancellationToken)	Accepts a pending connection request as a cancellable asynchronous operation.
AllowNatTraversal(Boolean)	Enables or disables Network Address Translation (NAT) traversal on a TcpListener instance.
BeginAcceptSocket(AsyncCallback, Object)	Begins an asynchronous operation to accept an incoming connection attempt.
BeginAcceptTcpClient(AsyncCallback, Object)	Begins an asynchronous operation to accept an incoming connection attempt.
Create(Int32)	Creates a new TcpListener instance to listen on the specified port.
Dispose()	Releases all resources used by the current TcpListener instance.
EndAcceptSocket(IAsyncResult)	Asynchronously accepts an incoming connection attempt and creates a new Socket to handle remote host communication.
EndAcceptTcpClient(IAsyncResult)	Asynchronously accepts an incoming connection attempt and creates a new TcpClient to handle remote host communication.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
Pending()	Determines if there are pending connection requests.
Start()	Starts listening for incoming connection requests.
Start(Int32)	Starts listening for incoming connection requests with a maximum number of pending connection.
Stop()	Closes the listener.
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• TcpClient