Socket.Listen Method (Int32)

 

Places a Socket in a listening state.

Namespace:   System.Net.Sockets
Assembly:  System (in System.dll)

public void Listen(
	int backlog
)

Parameters

backlog
Type: System.Int32

The maximum length of the pending connections queue.

Exception Condition
SocketException

An error occurred when attempting to access the socket. See the Remarks section for more information.

ObjectDisposedException

The Socket has been closed.

Listen causes a connection-oriented Socket to listen for incoming connection attempts. The backlog parameter specifies the number of incoming connections that can be queued for acceptance. To determine the maximum number of connections you can specify, retrieve the MaxConnections value. Listen does not block.

If you receive a SocketException, use the ErrorCode property to obtain the specific error code. After you have obtained this code, refer to the Windows Sockets version 2 API error code documentation in the MSDN library for a detailed description of the error. Use Accept or BeginAccept to accept a connection from the queue.

System_CAPS_noteNote

You must call the Bind method before calling Listen, or Listen will throw a SocketException.

System_CAPS_noteNote

This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.

System_CAPS_noteNote

The backlog parameter is limited to different values depending on the Operating System. You may specify a higher value, but the backlog will be limited based on the Operating System.

The following code example uses Socket to listen for incoming connections.

       // create the socket
       Socket listenSocket = new Socket(AddressFamily.InterNetwork, 
                                        SocketType.Stream,
                                        ProtocolType.Tcp);

       // bind the listening socket to the port
IPAddress hostIP = (Dns.Resolve(IPAddress.Any.ToString())).AddressList[0];
       IPEndPoint ep = new IPEndPoint(hostIP, port);
       listenSocket.Bind(ep); 

       // start listening
       listenSocket.Listen(backlog);

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Windows Phone Silverlight
Available since 8.0
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