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ff_axel

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Ping A Network Computer Using VB

I have a basic application that runs some SQL on a database (ODBC connection)on a Server on the network.  Depending on the results of the SQL, the application may then use the NT messaging service to "net send" a message to one or more computers also on the network. If the server is down however or network failure, the application fails, also if one of the computers that it sends a message to is 'off' then this slows up the application presumably while it times out.  What I would like to do is "ping" the computers involved, and use the reply to determine whether the computer was 'alive' or 'dead'. A simple coded example to do the following would be really useful...

   reply = ping 199.199.199.199
     if (reply)
        msgBox "Alive"
     else
        msgbox "Dead"
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AzraSound
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ff_axel

ASKER

Thanks for the prompt reply, however my machine crashes when I try to access the site.. ?
http://www.mvps.org/vbnet/code/network/ping.htm

i sent you the framed page anyways...that is the direct url
ok i'll post the code for you

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------------
Not My code but it works.
------------

With Visual Basic applications expanding more into the enterprise, basic networking functionality often needs to be duplicated by the application. Using the routine here, you will be able to ping any IP address passed.
Ping is a tool that helps to verify IP-level connectivity. When troubleshooting, the ping command is used to send an ICMP echo request to a target host name or IP address. Use ping whenever you need to verify that a host computer can connect to the TCP/IP network and network resources. You can also use the ping utility to isolate network hardware problems and incompatible configurations.

It is usually best to verify that a route exists between the local computer and a network host by first using ping and the IP address of the network host to which you want to connect. First try pinging the IP address of the target host to see if it will respond, because this is the simplest case.

The concept in the VB implementation is to pass to a routine the address to ping, and a message under 32 bytes that the ping should return if successful. This routine does not worked with named domains; it only works when passed the numerical address itself.

To test this application, you must be connected to a network or to your ISP via dial up networking (DUN).

I do not profess to know anything at all about networking or internet functions ... this code  (as a bas file only) was provided to me unsigned. If the author is known, I'd appreciate hearing from them so proper credit can be given. Furthermore, it is commented only as far as the author did, with a bit of MSDN descriptions thrown in.

Finally, just to keep the error message lines short (narrow), I've split them into multiple lines as needed.
 

 

 BAS Module Code
 
Add the following code to a BAS module:

--------------------------------------------------------------------------------
 

Option Explicit
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright ©1996-2000 VBnet, Randy Birch, All Rights Reserved.
' Some pages may also contain other copyrights by the author.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' You are free to use this code within your own applications,
' but you are expressly forbidden from selling or otherwise
' distributing this source code without prior written consent.
' This includes both posting free demo projects made from this
' code as well as reproducing the code in text or html format.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

Private Const IP_SUCCESS As Long = 0
Private Const IP_STATUS_BASE As Long = 11000
Private Const IP_BUF_TOO_SMALL As Long = (11000 + 1)
Private Const IP_DEST_NET_UNREACHABLE As Long = (11000 + 2)
Private Const IP_DEST_HOST_UNREACHABLE As Long = (11000 + 3)
Private Const IP_DEST_PROT_UNREACHABLE As Long = (11000 + 4)
Private Const IP_DEST_PORT_UNREACHABLE As Long = (11000 + 5)
Private Const IP_NO_RESOURCES As Long = (11000 + 6)
Private Const IP_BAD_OPTION As Long = (11000 + 7)
Private Const IP_HW_ERROR As Long = (11000 + 8)
Private Const IP_PACKET_TOO_BIG As Long = (11000 + 9)
Private Const IP_REQ_TIMED_OUT As Long = (11000 + 10)
Private Const IP_BAD_REQ As Long = (11000 + 11)
Private Const IP_BAD_ROUTE As Long = (11000 + 12)
Private Const IP_TTL_EXPIRED_TRANSIT As Long = (11000 + 13)
Private Const IP_TTL_EXPIRED_REASSEM As Long = (11000 + 14)
Private Const IP_PARAM_PROBLEM As Long = (11000 + 15)
Private Const IP_SOURCE_QUENCH As Long = (11000 + 16)
Private Const IP_OPTION_TOO_BIG As Long = (11000 + 17)
Private Const IP_BAD_DESTINATION As Long = (11000 + 18)
Private Const IP_ADDR_DELETED As Long = (11000 + 19)
Private Const IP_SPEC_MTU_CHANGE As Long = (11000 + 20)
Private Const IP_MTU_CHANGE As Long = (11000 + 21)
Private Const IP_UNLOAD As Long = (11000 + 22)
Private Const IP_ADDR_ADDED As Long = (11000 + 23)
Private Const IP_GENERAL_FAILURE As Long = (11000 + 50)
Private Const MAX_IP_STATUS As Long = (11000 + 50)
Private Const IP_PENDING As Long = (11000 + 255)
Private Const PING_TIMEOUT As Long = 500
Private Const WS_VERSION_REQD As Long = &H101
Private Const MIN_SOCKETS_REQD As Long = 1
Private Const SOCKET_ERROR As Long = -1
Private Const INADDR_NONE As Long = &HFFFFFFFF
Private Const MAX_WSADescription As Long = 256
Private Const MAX_WSASYSStatus As Long = 128

Private Type ICMP_OPTIONS
    Ttl             As Byte
    Tos             As Byte
    Flags           As Byte
    OptionsSize     As Byte
    OptionsData     As Long
End Type

Public Type ICMP_ECHO_REPLY
    Address         As Long
    status          As Long
    RoundTripTime   As Long
    DataSize        As Long 'formerly integer
   'Reserved        As Integer
    DataPointer     As Long
    Options         As ICMP_OPTIONS
    Data            As String * 250
End Type

Private Type WSADATA
   wVersion As Integer
   wHighVersion As Integer
   szDescription(0 To MAX_WSADescription) As Byte
   szSystemStatus(0 To MAX_WSASYSStatus) As Byte
   wMaxSockets As Long
   wMaxUDPDG As Long
   dwVendorInfo As Long
End Type

Private Declare Function IcmpCreateFile Lib "icmp.dll" () As Long

Private Declare Function IcmpCloseHandle Lib "icmp.dll" _
   (ByVal IcmpHandle As Long) As Long
   
Private Declare Function IcmpSendEcho Lib "icmp.dll" _
   (ByVal IcmpHandle As Long, _
    ByVal DestinationAddress As Long, _
    ByVal RequestData As String, _
    ByVal RequestSize As Long, _
    ByVal RequestOptions As Long, _
    ReplyBuffer As ICMP_ECHO_REPLY, _
    ByVal ReplySize As Long, _
    ByVal Timeout As Long) As Long
   
Private Declare Function WSAGetLastError Lib "WSOCK32.DLL" () As Long

Private Declare Function WSAStartup Lib "WSOCK32.DLL" _
   (ByVal wVersionRequired As Long, _
    lpWSADATA As WSADATA) As Long
   
Private Declare Function WSACleanup Lib "WSOCK32.DLL" () As Long

Private Declare Function gethostname Lib "WSOCK32.DLL" _
   (ByVal szHost As String, _
    ByVal dwHostLen As Long) As Long
   
Private Declare Function gethostbyname Lib "WSOCK32.DLL" _
   (ByVal szHost As String) As Long

Private Declare Sub CopyMemory Lib "kernel32" _
   Alias "RtlMoveMemory" _
  (xDest As Any, _
   xSource As Any, _
   ByVal nbytes As Long)
   
Private Declare Function inet_addr Lib "WSOCK32.DLL" _
   (ByVal s As String) As Long
   

Public Function GetStatusCode(status As Long) As String

   Dim msg As String
   
   Select Case status
      Case IP_SUCCESS:               msg = "ip success"
      Case INADDR_NONE:              msg = "inet_addr: bad IP format"
      Case IP_BUF_TOO_SMALL:         msg = "ip buf too_small"
      Case IP_DEST_NET_UNREACHABLE:  msg = "ip dest net unreachable"
      Case IP_DEST_HOST_UNREACHABLE: msg = "ip dest host unreachable"
      Case IP_DEST_PROT_UNREACHABLE: msg = "ip dest prot unreachable"
      Case IP_DEST_PORT_UNREACHABLE: msg = "ip dest port unreachable"
      Case IP_NO_RESOURCES:          msg = "ip no resources"
      Case IP_BAD_OPTION:            msg = "ip bad option"
      Case IP_HW_ERROR:              msg = "ip hw_error"
      Case IP_PACKET_TOO_BIG:        msg = "ip packet too_big"
      Case IP_REQ_TIMED_OUT:         msg = "ip req timed out"
      Case IP_BAD_REQ:               msg = "ip bad req"
      Case IP_BAD_ROUTE:             msg = "ip bad route"
      Case IP_TTL_EXPIRED_TRANSIT:   msg = "ip ttl expired transit"
      Case IP_TTL_EXPIRED_REASSEM:   msg = "ip ttl expired reassem"
      Case IP_PARAM_PROBLEM:         msg = "ip param_problem"
      Case IP_SOURCE_QUENCH:         msg = "ip source quench"
      Case IP_OPTION_TOO_BIG:        msg = "ip option too_big"
      Case IP_BAD_DESTINATION:       msg = "ip bad destination"
      Case IP_ADDR_DELETED:          msg = "ip addr deleted"
      Case IP_SPEC_MTU_CHANGE:       msg = "ip spec mtu change"
      Case IP_MTU_CHANGE:            msg = "ip mtu_change"
      Case IP_UNLOAD:                msg = "ip unload"
      Case IP_ADDR_ADDED:            msg = "ip addr added"
      Case IP_GENERAL_FAILURE:       msg = "ip general failure"
      Case IP_PENDING:               msg = "ip pending"
      Case PING_TIMEOUT:             msg = "ping timeout"
      Case Else:                     msg = "unknown  msg returned"
   End Select
   
   GetStatusCode = CStr(status) & "   [ " & msg & " ]"
   
End Function



Public Function Ping(sAddress As String,
                     sDataToSend As String,
                     ECHO As ICMP_ECHO_REPLY) As Long

  'If Ping succeeds :
  '.RoundTripTime = time in ms for the ping to complete,
  '.Data is the data returned (NULL terminated)
  '.Address is the Ip address that actually replied
  '.DataSize is the size of the string in .Data
  '.Status will be 0
  '
  'If Ping fails .Status will be the error code
   
   Dim hPort As Long
   Dim dwAddress As Long
   
  'convert the address into a long representation
   dwAddress = inet_addr(szAddress)
   
  'if a valid address..
   If dwAddress <> INADDR_NONE Then
   
     'open a port
      hPort = IcmpCreateFile()
     
     'and if successful,
      If hPort Then
     
        'ping it.
         Call IcmpSendEcho(hPort, _
                           dwAddress, _
                           sDataToSend, _
                           Len(sDataToSend), _
                           0, _
                           ECHO, _
                           Len(ECHO), _
                           PING_TIMEOUT)

        'return the status as ping succes and close
         Ping = ECHO.status
         Call IcmpCloseHandle(hPort)
     
      End If  
     
   Else:
        'the address format was probably invalid
         Ping = INADDR_NONE
         
   End If
 
End Function
   

Public Sub SocketsCleanup()
   
   If WSACleanup() <> 0 Then
       MsgBox "Windows Sockets error occurred in Cleanup.", vbExclamation
   End If
   
End Sub


Public Function SocketsInitialize() As Boolean

   Dim WSAD As WSADATA
   
   SocketsInitialize = WSAStartup(WS_VERSION_REQD, WSAD) = IP_SUCCESS
   
End Function

'--end block--'
   

 Form Code
 
To a form add a command button (Command1), two text boxes (Text1, Text2) to the top of the form, and six text boxes in a control array (Text4(0) - Text4(5)) below. The labels are optional. Add the following to the form:

--------------------------------------------------------------------------------
 

Option Explicit

Private Sub Command1_Click()
   
   Dim ECHO As ICMP_ECHO_REPLY
   Dim pos As Long
   Dim success As Long
   
   If SocketsInitialize() Then
   
     'ping the ip passing the address, text
     'to send, and the ECHO structure.
      success = Ping((Text1.Text), (Text2.Text), ECHO)
     
     'display the results
      Text4(0).Text = GetStatusCode(success)
      Text4(1).Text = ECHO.Address
      Text4(2).Text = ECHO.RoundTripTime & " ms"
      Text4(3).Text = ECHO.DataSize & " bytes"
     
      If Left$(ECHO.Data, 1) <> Chr$(0) Then
         pos = InStr(ECHO.Data, Chr$(0))
         Text4(4).Text = Left$(ECHO.Data, pos - 1)
      End If
   
      Text4(5).Text = ECHO.DataPointer
     
      SocketsCleanup
     
   Else
   
        MsgBox "Windows Sockets for 32 bit Windows " & _
               "environments is not successfully responding."
   
   End If
   
End Sub