TcpListener.Start Method (Int32)
Starts listening for incoming connection requests with a maximum number of pending connection.
Assembly: System (in System.dll)
An error occurred while accessing the socket. See the Remarks section for more information.
The backlog parameter is less than zero or exceeds the maximum number of permitted connections.
The underlying Socket is null.
The Start method initializes the underlying Socket, binds it to a local endpoint, and listens for incoming connection attempts. If a connection request is received, Start will queue the request and continue listening for additional requests until you call the Stop method. If TcpListener receives a connection request after it has already queued the maximum number of connections it will throw a SocketException on the client.
To remove a connection from the incoming connection queue, use either the AcceptTcpClient method or the AcceptSocket method. The AcceptTcpClient method will remove a connection from the queue and return a TcpClient that you can use to send and receive data. The AcceptSocket method will return a Socket that you can use to do the same. If your application only requires synchronous I/O, use the AcceptTcpClient. For more detailed behavioral control, use AcceptSocket method. Both of these methods block until a connection request is available in the queue.
Use the SocketException.ErrorCode property to obtain the specific error code and refer to the Windows Sockets version 2 API error code documentation in the MSDN library at http://msdn.microsoft.com/library/ for a detailed description of the error.
This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.
The following code example demonstrates how Start is used to listen for incoming client connection attempts.