Ping from VB6

Posted on 2008-11-18
Medium Priority
Last Modified: 2012-05-05
I have an application that needs access to an Internet website, which I need to distribute. I need to put together a tool to test that Internet access is permissible, and that a firewall is not blocking access.
Can I do this using ping? I want to use VB6 for the tool
If yes, how do I know if the ping was successful, i.e access was allowed / disallowed?
If no, what other method can I use?

This must be able to run on Windows 2000, XP & Vista
Question by:TimTDP

Expert Comment

ID: 22988103

Use this function, works fine!

Regards, Dennis

Public Function PingSilent(strComputer As String) As Integer
    Dim oPing As SWbemObjectSet
    Dim oStatus As SWbemObject
    Set oPing = GetObject("winmgmts:{impersonationLevel=impersonate}"). _
       InstancesOf("Win32_PingStatus where address='" & strComputer & "'")
    For Each oStatus In oPing
        If IsNull(oStatus.StatusCode) Or oStatus.StatusCode <> 0 Then
            PingSilent = 0 'not reachable
            PingSilent = 1 'is alive
        End If
End Function

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LVL 13

Expert Comment

ID: 22990899

good morning!

I've been using this...
Might give it a try...

if TestPing(strComputer) = True then
       debug.print "Connected"
       debug.print "Disconnected"
end if

Function TestPing(sName)
      Dim cPingResults, oPingResult
      Set cPingResults = GetObject("winmgmts://./root/cimv2").ExecQuery("SELECT * FROM Win32_PingStatus WHERE Address = '" & sName & "'")
     For Each oPingResult In cPingResults
            If oPingResult.StatusCode = 0 Then
                  TestPing = True
                  TestPing = False
            End If

End Function

i hope i could give u idea...

LVL 12

Expert Comment

ID: 22993343
Ping is not necessarily the ideal solution.  The application might be used in an environment where ICMP echos are able to traverse the network but HTTP traffic is not.

Therefore I'd recommend attempting to connect to the website and properly handling the various responses - some of which may be:
TCP connection request refused.
TCP connection TimedOut.
ICMP Net Unreachable.
ICMP Host Unreachable.

and of course a successful connection.
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Author Comment

ID: 22993399
Hi jahboite

Can you elaborate further?
LVL 12

Accepted Solution

jahboite earned 360 total points
ID: 22993579
Ping utilises an Internet Protocol (IP) named ICMP.  Specifically, you send an ICMP Echo Request to the remote host and wait for an ICMP Echo Reply to come back.

When connecting to a website, you are utilising an IP named TCP.  My point was that if you want to see if the web server is reachable, you should check that it's reachable over the same protocol as you want to talk to it because the ICMP traffic might be allowed on the network and TCP traffic might not - or even the other way around.

Therefore it would seem logical that your application which connects to a website needs only to properly handle any errors arising from a lack of connectivity or an unreachable website.

What method does your application use to connect to the website?

Author Comment

ID: 22993608
Protocol: HTTP
Port: 80
LVL 12

Expert Comment

ID: 22993675
Yes, yes, but I mean what code does the application use to access the website?  Is it using the sockets API or something like URLDownloadToFile?

Author Comment

ID: 23003617
Hi jahboite

It uses URLDownloadToFile.
LVL 12

Expert Comment

ID: 23007098
And is checking the return value from URLDownloadToFile (which is 0 on a successful start of download and non-zero otherwise) not sufficient for your needs?

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