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How to ping an IP address by using sockets in Visual Basic .NET

SUMMARY
This step-by-step article describes how to use sockets in Microsoft Visual Basic .NET to ping an Internet Protocol (IP) address. The PING command uses Internet Control Message Protocol (ICMP) to test a network connection. The response time to ping a particular IP address is calculated and displayed. This article uses the System.Net.Sockets API of Visual Basic .NET to ping an IP address.

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Requirements

This article assumes that you are familiar with the following topics:
  • Programming with Visual Basic .NET
  • Sockets
The following list outlines the recommended hardware, software, network infrastructure, and service packs that you need:
  • Microsoft Windows 2000, Microsoft Windows XP, or Microsoft Windows Server 2003
  • Microsoft Visual Basic .NET
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Declare an ICMP packet structure

ICMP supports packets that contain error messages, control messages, and informational messages. The PING command uses ICMP to test a network connection. Use the following code to declare the structure of an ICMP packet and to declare a method to calculate the total number of bytes in a packet:
   Structure IcmpPacket#Region "PUBLIC MEMBER VARIABLES"      Dim type_message As Byte                ' Type of message.      Dim subCode_type As Byte                ' Type of sub-code.      Dim complement_checkSum As UInt16       ' One's complement checksum for the structure.      Dim identifier As UInt16                ' Identifier.      Dim sequenceNumber As UInt16            ' Sequence number.      Dim data() As Byte                      ' Data.#End Region#Region "PUBLIC MEMBER METHODS"      Public Sub Initialize(ByVal type As Byte, ByVal subCode As Byte, ByVal payload() As Byte)         Dim index As Integer         Dim buffer_icmpPacket() As Byte         Dim cksumBuffer() As UInt16         Dim icmpHeaderBufferIndex As Int32 = 0         Me.type_message = type         Me.subCode_type = subCode         complement_checkSum = UInt16.Parse("0")         identifier = UInt16.Parse("45")         sequenceNumber = UInt16.Parse("0")         Data = payload         ' Declare a variable to store the total packet size.         ' Call the Serialize method to count the total number of bytes in the packet.         buffer_icmpPacket = Serialize()         ' Resize a UInt16 array to half the size of the packet.         ReDim cksumBuffer((buffer_icmpPacket.Length() \ 2) - 1)         ' Initialize the UInt16 array.         For index = 0 To (cksumBuffer.Length() - 1)            cksumBuffer(index) = BitConverter.ToUInt16(buffer_icmpPacket, icmpHeaderBufferIndex)            icmpHeaderBufferIndex += 2         Next index         'Call a method that returns a checksum.         complement_checkSum = MCheckSum.Calculate(cksumBuffer, cksumBuffer.Length())      End Sub      Public Function Size() As Integer         Return (8 + Data.Length())      End Function      ' The Serialize method converts the packet to a byte array to calculate the total size.      Public Function Serialize() As Byte()         Dim b_seq() As Byte = BitConverter.GetBytes(sequenceNumber)         Dim b_cksum() As Byte = BitConverter.GetBytes(complement_checkSum)         Dim b_id() As Byte = BitConverter.GetBytes(identifier)         Dim index As Int32 = 0         Dim buffer() As Byte         ReDim buffer(Size() - 1)         ' Serialize the structure into the array.         buffer(0) = type_message         buffer(1) = subCode_type         index += 2         Array.Copy(b_cksum, 0, buffer, index, 2)         index += 2         Array.Copy(b_id, 0, buffer, index, 2)         index += 2         Array.Copy(b_seq, 0, buffer, index, 2)         index += 2         ' Copy the data.         If (Data.Length() > 0) Then            Array.Copy(Data, 0, buffer, index, Data.Length())         End If         Return buffer      End Function#End Region   End Structure
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Define the CPing class

The CPing class contains methods to accept the host name or the IP address of a server as input, to ping the host name or IP address, and to display the response time.
   ' The CPing class.   Public Class CPing#Region "MEMBER CONSTANTS"      Private Const DEFAULT_TIMEOUT As Integer = 1000      Private Const SOCKET_ERROR As Integer = -1      Private Const PING_ERROR As Integer = -1      Private Const ICMP_ECHO As Integer = 8      Private Const DATA_SIZE As Integer = 32      Private Const RECV_SIZE As Integer = 128#End Region#Region "MEMBER VARIABLES"      Private _open As Boolean = False      Private _initialized As Boolean      Private _recvBuffer() As Byte      Private _packet As IcmpPacket      Private _hostName As String      Private _server As EndPoint      Private _local As EndPoint      Private _socket As Socket#End Region#Region "CONSTRUCTORS & FINALIZER"      Public Sub New(ByVal hostName As String)         Me.HostName() = hostName         ReDim _recvBuffer(RECV_SIZE - 1)      End Sub      Public Sub New()         ' Set the default host name to the local host.         Me.HostName() = Dns.GetHostName()         ReDim _recvBuffer(RECV_SIZE - 1)      End Sub      Private Overloads Sub finalize()         ' Make sure that you close the socket.         Me.Close()         Erase _recvBuffer      End Sub#End Region#Region "MEMBER METHODS"      ' Get and set the current host name.      Public Property HostName() As String         Get            Return _hostName         End Get         Set(ByVal Value As String)            _hostName = Value            ' If the CPing object is already open, close it and then reopen it by using a new host name.            If (_open) Then               Me.Close()               Me.Open()            End If         End Set      End Property      ' Get the state (open or closed).      Public ReadOnly Property IsOpen() As Boolean         Get            Return _open         End Get      End Property      ' Create a socket to host remote end points and local end points.      Public Function Open() As Boolean         Dim payload() As Byte         If (Not _open) Then            Try               ' Initialize the packet.               ReDim payload(DATA_SIZE)               _packet.Initialize(ICMP_ECHO, 0, payload)               ' Initialize an ICMP socket.               _socket = New Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp)               ' Set the server end point.               _server = New IPEndPoint(Dns.GetHostByName(_hostName).AddressList(0), 0)               ' Set the receiving end point as your client computer.               _local = New IPEndPoint(Dns.GetHostByName(Dns.GetHostName()).AddressList(0), 0)               _open = True            Catch               Return False            End Try         End If         Return True      End Function      ' Destroy the socket and the end points (if necessary).      Public Function Close() As Boolean         If (_open) Then            _socket.Close()            _socket = Nothing            _server = Nothing            _local = Nothing            _open = False         End If         Return True      End Function      ' Perform a PING operation.      Public Overloads Function Ping() As Integer         Return Ping(DEFAULT_TIMEOUT)      End Function      ' The Ping method performs a PING operation.      Public Overloads Function Ping(ByVal timeOutMilliSeconds As Integer) As Integer         ' Initialize the time-out value.         Dim timeOut As Integer = timeOutMilliSeconds + Environment.TickCount()         ' Send the packet.         If (SOCKET_ERROR = _socket.SendTo(_packet.Serialize(), _packet.Size(), 0, _server)) Then            Return PING_ERROR         End If         ' Use the following loop to check the response time until you receive a time-out.         Do            ' Poll the read buffer every millisecond.            ' If data exists, read the data and return the round-trip time.            If (_socket.Poll(1000, SelectMode.SelectRead)) Then               _socket.ReceiveFrom(_recvBuffer, RECV_SIZE, 0, _local)               Return (timeOutMilliSeconds - (timeOut - Environment.TickCount()))            ElseIf (Environment.TickCount() >= timeOut) Then               Return PING_ERROR            End If         Loop While (True)      End Function#End Region   End Class
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Calculate the checksum value

The following code contains a Calculate method to calculate the checksum value. This code also contains unions that the Calculate method uses.
#Region "MEMBER METHODS"      <StructLayout(LayoutKind.Explicit)> _                 Structure UNION_INT16         <FieldOffset(0)> Dim lsb As Byte      ' Least significant byte         <FieldOffset(1)> Dim msb As Byte      ' Most significant byte         <FieldOffset(0)> Dim w16 As Short      End Structure      <StructLayout(LayoutKind.Explicit)> _      Structure UNION_INT32         <FieldOffset(0)> Dim lsw As UNION_INT16     ' Most significant word         <FieldOffset(2)> Dim msw As UNION_INT16     ' Least significant word         <FieldOffset(0)> Dim w32 As Integer      End Structure      ' The Calculate method calculates the checksum value.      Public Function Calculate(ByRef buffer() As UInt16, ByVal size As Int32) As UInt16         Dim counter As Int32 = 0         Dim cksum32 As UNION_INT32         Do While (size > 0)            cksum32.w32 += Convert.ToInt32(buffer(counter))            counter += 1            size -= 1         Loop         cksum32.w32 = cksum32.msw.w16 + cksum32.lsw.w16 + cksum32.msw.w16         Return Convert.ToUInt16(cksum32.lsw.w16 Xor &HFFFF)      End Function#End Region
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Implement the user interface

The following code implements the user interface. This code determines whether the host name or the IP address that the user types is empty, and then alerts the user to type a host name or an IP address in the specified format. After the user types a host name or an IP address, the application establishes a socket connection to the corresponding IP address (if this address is in the same network), and then the application sends a data packet by using ICMP. The application then calculates the time taken (in milliseconds) to send and receive the data packet, and then the application displays this value. If the host name or the IP address is not in the same network or if the user types an invalid IP address or an invalid host name, the application displays a message.
Sub Main()   Dim Packet As New ICMP_Packet.CPing()   Dim retValue   Console.WriteLine("Enter the IP address or the host name to ping: ")   ' Accept a host name or an IP address.   Packet.HostName = Trim(Console.ReadLine())   ' Determine whether the user has typed only spaces instead of a host name or an IP address.   If Packet.HostName = "" Then      Console.WriteLine("Please enter an IP address (in the N.N.N.N format) or a host name")   Else      ' Determine whether you can establish a socket connection to the IP address.      If Packet.Open Then         ' Establish a socket connection, and then send a packet using ICMP.         retValue = Packet.Ping         If retValue <> -1 Then            ' Display the response time in milliseconds.            Console.WriteLine("Approximate response time : " & retValue)         Else            Console.WriteLine("Host Unreachable")         End If      Else         Console.WriteLine("No host found")      End If            Packet.Close()   End If   Console.WriteLine("Press ENTER to quit.")   Console.ReadLine()End Sub
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Create a console application

  1. Start Microsoft Visual Studio .NET.
  2. On the File menu, point to New, and then click Project. The New Project dialog box appears.
  3. Under Project Types, click Visual Basic Projects.
  4. Under Templates, click Console Application.
  5. In the Name box, type MyConsoleApplication.

    Note MyConsoleApplication is a sample Visual Basic .NET application.
  6. In the Location box, type the location where you want to save the MyConsoleApplication project, and then click OK.

    By default, the Module1.vb file is created.
  7. In the Module1.vb file, replace the existing code with the following code:
    Imports System.Net.SocketsImports System.NetImports SystemImports System.Runtime.InteropServicesNamespace ICMP_Packet   ' Define the structure of an ICMP packet.   ' This structure contains packet information.   Structure IcmpPacket#Region "PUBLIC MEMBER VARIABLES"      Dim type_message As Byte                ' type of message      Dim subCode_type As Byte                ' type of sub-code      Dim complement_checkSum As UInt16       ' one's complement checksum for the structure      Dim identifier As UInt16                ' identifier      Dim sequenceNumber As UInt16            ' sequence number        Dim data() As Byte                      ' data#End Region#Region "PUBLIC MEMBER METHODS"      Public Sub Initialize(ByVal type As Byte, ByVal subCode As Byte, ByVal payload() As Byte)         Dim index As Integer         Dim buffer_icmpPacket() As Byte         Dim cksumBuffer() As UInt16         Dim icmpHeaderBufferIndex As Int32 = 0         Me.type_message = type         Me.subCode_type = subCode         complement_checkSum = UInt16.Parse("0")         identifier = UInt16.Parse("45")         sequenceNumber = UInt16.Parse("0")         Data = payload         ' Declare a variable to store the total packet size.         ' Call the Serialize method to count the total number of bytes in the packet.         buffer_icmpPacket = Serialize()         ' Resize a UInt16 array to half the size of the packet.         ReDim cksumBuffer((buffer_icmpPacket.Length() \ 2) - 1)         ' Initialize the UInt16 array.         For index = 0 To (cksumBuffer.Length() - 1)            cksumBuffer(index) = BitConverter.ToUInt16(buffer_icmpPacket, icmpHeaderBufferIndex)            icmpHeaderBufferIndex += 2         Next index         'Call a method that returns a checksum.         complement_checkSum = MCheckSum.Calculate(cksumBuffer, cksumBuffer.Length())      End Sub      Public Function Size() As Integer         Return (8 + Data.Length())      End Function      ' The Serialize method converts the packet to a byte array to calculate the total size.      Public Function Serialize() As Byte()         Dim b_seq() As Byte = BitConverter.GetBytes(sequenceNumber)         Dim b_cksum() As Byte = BitConverter.GetBytes(complement_checkSum)         Dim b_id() As Byte = BitConverter.GetBytes(identifier)         Dim index As Int32 = 0         Dim buffer() As Byte         ReDim buffer(Size() - 1)         ' Serialize the structure into the array.         buffer(0) = type_message         buffer(1) = subCode_type         index += 2         Array.Copy(b_cksum, 0, buffer, index, 2)         index += 2         Array.Copy(b_id, 0, buffer, index, 2)         index += 2         Array.Copy(b_seq, 0, buffer, index, 2)         index += 2         ' Copy the data.         If (Data.Length() > 0) Then            Array.Copy(Data, 0, buffer, index, Data.Length())         End If         Return buffer      End Function#End Region   End Structure   ' The CPing class.   Public Class CPing#Region "MEMBER CONSTANTS"      Private Const DEFAULT_TIMEOUT As Integer = 1000      Private Const SOCKET_ERROR As Integer = -1      Private Const PING_ERROR As Integer = -1      Private Const ICMP_ECHO As Integer = 8      Private Const DATA_SIZE As Integer = 32      Private Const RECV_SIZE As Integer = 128#End Region#Region "MEMBER VARIABLES"      Private _open As Boolean = False      Private _initialized As Boolean      Private _recvBuffer() As Byte      Private _packet As IcmpPacket      Private _hostName As String      Private _server As EndPoint      Private _local As EndPoint      Private _socket As Socket#End Region#Region "CONSTRUCTORS & FINALIZER"      Public Sub New(ByVal hostName As String)         Me.HostName() = hostName         ReDim _recvBuffer(RECV_SIZE - 1)      End Sub      Public Sub New()         ' Set the default host name to the local host.         Me.HostName() = Dns.GetHostName()         ReDim _recvBuffer(RECV_SIZE - 1)      End Sub      Private Overloads Sub finalize()         ' Ensure that you close the socket.         Me.Close()         Erase _recvBuffer      End Sub#End Region#Region "MEMBER METHODS"      ' Get and set the current host name.      Public Property HostName() As String         Get            Return _hostName         End Get         Set(ByVal Value As String)            _hostName = Value            ' If the CPing object is already open, close it and then reopen it by using a new host name.            If (_open) Then               Me.Close()               Me.Open()            End If         End Set      End Property      ' Get the state (open or closed).      Public ReadOnly Property IsOpen() As Boolean         Get            Return _open         End Get      End Property      ' Create a socket to host remote end points and local end points.      Public Function Open() As Boolean         Dim payload() As Byte         If (Not _open) Then            Try               ' Initialize the packet.               ReDim payload(DATA_SIZE)               _packet.Initialize(ICMP_ECHO, 0, payload)               ' Initialize an ICMP socket.               _socket = New Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp)               ' Set the server end point.               _server = New IPEndPoint(Dns.GetHostByName(_hostName).AddressList(0), 0)               ' Set the receiving end point as your client computer.               _local = New IPEndPoint(Dns.GetHostByName(Dns.GetHostName()).AddressList(0), 0)               _open = True            Catch               Return False            End Try         End If         Return True      End Function      ' Destroy the socket and end points (if necessary).      Public Function Close() As Boolean         If (_open) Then            _socket.Close()            _socket = Nothing            _server = Nothing            _local = Nothing            _open = False         End If         Return True      End Function      ' Perform a PING operation.      Public Overloads Function Ping() As Integer         Return Ping(DEFAULT_TIMEOUT)      End Function      ' The Ping method performs a PING operation.      Public Overloads Function Ping(ByVal timeOutMilliSeconds As Integer) As Integer         ' Initialize the time-out value.         Dim timeOut As Integer = timeOutMilliSeconds + Environment.TickCount()         ' Send the packet.         If (SOCKET_ERROR = _socket.SendTo(_packet.Serialize(), _packet.Size(), 0, _server)) Then            Return PING_ERROR         End If         ' Use the following loop to check the response time until you receive a time-out.         Do            ' Poll the read buffer every millisecond.            ' If data exists, read the data and return the round-trip time.            If (_socket.Poll(1000, SelectMode.SelectRead)) Then               _socket.ReceiveFrom(_recvBuffer, RECV_SIZE, 0, _local)               Return (timeOutMilliSeconds - (timeOut - Environment.TickCount()))            ElseIf (Environment.TickCount() >= timeOut) Then               Return PING_ERROR            End If         Loop While (True)      End Function#End Region   End Class   ' The MCheckSum module contains the static Calculate method.   Module MCheckSum#Region "MEMBER METHODS"      <StructLayout(LayoutKind.Explicit)> _                 Structure UNION_INT16         <FieldOffset(0)> Dim lsb As Byte      ' Least significant byte         <FieldOffset(1)> Dim msb As Byte      ' Most significant byte         <FieldOffset(0)> Dim w16 As Short      End Structure      <StructLayout(LayoutKind.Explicit)> _      Structure UNION_INT32         <FieldOffset(0)> Dim lsw As UNION_INT16     ' Most significant word         <FieldOffset(2)> Dim msw As UNION_INT16     ' Least significant word         <FieldOffset(0)> Dim w32 As Integer      End Structure      ' The Calculate method calculates the checksum value.      Public Function Calculate(ByRef buffer() As UInt16, ByVal size As Int32) As UInt16         Dim counter As Int32 = 0         Dim cksum32 As UNION_INT32         Do While (size > 0)            cksum32.w32 += Convert.ToInt32(buffer(counter))            counter += 1            size -= 1         Loop         cksum32.w32 = cksum32.msw.w16 + cksum32.lsw.w16 + cksum32.msw.w16         Return Convert.ToUInt16(cksum32.lsw.w16 Xor &HFFFF)      End Function#End Region      Sub Main()         Dim Packet As New ICMP_Packet.CPing()         Dim retValue         Console.WriteLine("Enter the IP address or the host name to ping: ")         ' Accept a host name or an IP address.         Packet.HostName = Trim(Console.ReadLine())         ' Determine whether the user has typed only spaces instead of a host name or an IP address.         If Packet.HostName = "" Then            Console.WriteLine("Please enter an IP address (in the N.N.N.N format) or a host name")         Else            ' Determine whether you can establish a socket connection to the IP address.            If Packet.Open Then               ' Establish a socket connection, and then send a packet by using ICMP.               retValue = Packet.Ping               If retValue <> -1 Then                  ' Display the response time in milliseconds.                  Console.WriteLine("Approximate response time : " & retValue)               Else                  Console.WriteLine("Host Unreachable")               End If            Else               Console.WriteLine("No host found")            End If                        Packet.Close()         End If         Console.WriteLine("Press ENTER to quit.")         Console.ReadLine()      End Sub   End ModuleEnd Namespace
  8. In Solution Explorer, click the MyConsoleApplication project.
  9. On the Project menu, click Properties.
  10. In the MyConsoleApplication Property Pages dialog box, select Sub Main from the Startup object drop-down list box, and then click OK.
  11. On the Debug menu, click Start.
  12. At the command prompt that appears, type a host name or an IP address, and then press ENTER.
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REFERENCES
For more information, visit the following Microsoft Developer Network (MSDN) Web sites:For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
300197 HOW TO: Ping an IP address with Visual Basic by using ICMP
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Article ID: 828993 - Last Review: 04/19/2007 07:39:18 - Revision: 1.3

  • Microsoft Visual Basic .NET 2003 Standard Edition
  • Microsoft Visual Basic .NET 2002 Standard Edition
  • kbnetwork kbhowtomaster kbwinsock KB828993
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