Socket.IOControl Method (IOControlCode, Byte[], Byte[])

Note: This method is new in the .NET Framework version 2.0.

Sets low-level operating modes for the Socket using the IOControlCode enumeration to specify control codes.

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

Public Function IOControl ( _
	ioControlCode As IOControlCode, _
	optionInValue As Byte(), _
	optionOutValue As Byte() _
) As Integer
Dim instance As Socket
Dim ioControlCode As IOControlCode
Dim optionInValue As Byte()
Dim optionOutValue As Byte()
Dim returnValue As Integer

returnValue = instance.IOControl(ioControlCode, optionInValue, optionOutValue)
public int IOControl (
	IOControlCode ioControlCode, 
	byte[] optionInValue, 
	byte[] optionOutValue
public function IOControl (
	ioControlCode : IOControlCode, 
	optionInValue : byte[], 
	optionOutValue : byte[]
) : int



A IOControlCode value that specifies the control code of the operation to perform.


An array of type Byte that contains the input data required by the operation.


An array of type Byte that contains the output data returned by the operation.

Return Value

The number of bytes in the optionOutValue parameter.

Exception typeCondition


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


The Socket has been closed.


An attempt was made to change the blocking mode without using the Blocking property.

This method provides low-level access to the operating system Socket underlying the current instance of the Socket class. For more, see the WSAIoctl documentation in the MSDN library.


If you receive a SocketException, 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 compares the results of calling IOControl with DataToRead and the Available property.

No code example is currently available or this language may not be supported.
static void DisplayPendingByteCount(Socket s)
    ubyte outValue[] = BitConverter.GetBytes(0);
    // Check how many bytes have been received.
    s.IOControl(IOControlCode.DataToRead, null, outValue);
    UInt32 bytesAvailable = BitConverter.ToUInt32(outValue, 0);
    //ToDo: Unsigned Integers not supported- converted to int
    Console.Write("server has {0} bytes pending. ",
    Console.WriteLine("Available property says {1}.", 
} //DisplayPendingByteCount

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

Community Additions