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Socket.Bind(EndPoint) Method


Associates a Socket with a local endpoint.

 void Bind(System::Net::EndPoint ^ localEP);
public void Bind (System.Net.EndPoint localEP);
member this.Bind : System.Net.EndPoint -> unit
Public Sub Bind (localEP As EndPoint)



The local EndPoint to associate with the Socket.


localEP is null.

An error occurred when attempting to access the socket.

The Socket has been closed.

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


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

   aSocket->Bind( anEndPoint );
catch ( Exception^ e ) 
   Console::WriteLine( "Winsock error: {0}", e );
try {
catch (Exception e) {
    Console.WriteLine("Winsock error: " + e.ToString());
Catch e As Exception
    Console.WriteLine("Winsock error: " & e.ToString())
End Try


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 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 a UDP socket wants to receive interface information on received packets, the SetSocketOption method should be explicitly called with the socket option set to PacketInformation immediately after calling the Bind method.


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 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 .NET Framework.

Applies to

See also