Socket.Bind Method

Associates a Socket with a local endpoint.

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

Public Sub Bind ( _
	localEP As EndPoint _
Dim instance As Socket
Dim localEP As EndPoint

public void Bind (
	EndPoint localEP
public function Bind (
	localEP : EndPoint
Not applicable.



The local EndPoint to associate with the Socket.

Exception typeCondition


localEP is a null reference (Nothing in Visual Basic).


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


The Socket has been closed.


A caller higher in the call stack does not have permission for the requested operation.

Use the Bind method if you need to use a specific local endpoint. You must call Bind before you can call the Listen method. You do not need to call Bind before using the Connect method unless you need to use a specific local endpoint. You can use the Bind method on both connectionless and connection-oriented protocols.

Before calling Bind, you must first create the local IPEndPoint from which you intend to communicate data. If you do not care which local address is assigned, you can create an IPEndPoint using System.Net.IPAddress.Any as the address parameter, and the underlying service provider will assign the most appropriate network address. This might help simplify your application if you have multiple network interfaces. If you do not care which local port is used, you can create an IPEndPoint using 0 for the port number. In this case, the service provider will assign an available port number between 1024 and 5000.

If you use the above approach, you can discover what local network address and port number has been assigned by calling the LocalEndPoint. If you are using a connection-oriented protocol, LocalEndPoint will not return the locally assigned network address until after you have made a call to the Connect or EndConnect method. If you are using a connectionless protocol, you will not have access to this information until you have completed a send or receive.


If you intend to receive multicast datagrams, you must call the Bind method with a multicast port number.


You must call the Bind method if you intend to receive connectionless datagrams using the ReceiveFrom method.


If you receive a SocketException when calling the Bind method, use the SocketException.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.


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

The following code example binds a Socket using the specified local endpoint.

Catch e As Exception
    Console.WriteLine("Winsock error: " & e.ToString())
End Try

try {
catch (System.Exception e) {
    Console.WriteLine(("Winsock error: " + e.ToString()));

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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