ping

[Garry]

How do I ping a computer from a Nt machine. I want to get a response back and I have to run this application every half and hour to test if the server is running.

[Aaron Young]

Try this Example I put together using the Winsock APIs:

For this Example you need a Form with 2 Textboxes and a CommandButton..

private Const MAX_WSADescription = 256
private Const MAX_WSASYSStatus = 128
private Const WS_VERSION_REQD = &H101

private Type HOSTENT
hName as Long
hAliases as Long
hAddrType as Integer
hLen as Integer
hAddrList as Long
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 Integer
wMaxUDPDG as Integer
dwVendorInfo as Long
End Type

private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (hpvDest as Any, byval hpvSource as Long, byval cbCopy as Long)
private Declare Function gethostbyname Lib "WSOCK32.DLL" (byval szHost as string) 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 Function GetIPAddress(byval sHost as string) as string

Dim I as Integer
Dim lHost as Long
Dim lIP as Long
Dim sIP() as Byte
Dim sFullIP as string
Dim tHost as HOSTENT
Dim tSocket as WSADATA

'Establish an Open Socket
If WSAStartup(WS_VERSION_REQD, tSocket) <> 0 then Exit Function

'Attempt to Locate Data pointer for Specified Host Name
lHost = gethostbyname(sHost)

If lHost = 0 then
MsgBox "Unable to Locate Host."
else
'get the Host Info
CopyMemory tHost, lHost, len(tHost)
'Extract the Address of the IP Data from the Addresslist Pointer
CopyMemory lIP, tHost.hAddrList, len(tHost.hAddrList)
'Build a Tempory array to hold the IP Values
ReDim sIP(tHost.hLen - 1)
'Copy the IP Values into the Array
CopyMemory sIP(0), lIP, tHost.hLen
'Build the IP Address
for I = 0 to tHost.hLen - 1
sFullIP = sFullIP & "." & sIP(I)
next
'Trim of the Preceeding Period
GetIPAddress = mid(sFullIP, 2)
End If

'Close up the Socket
Call WSACleanup

End Function

private Sub Command1_Click()
Text2 = GetIPAddress(Text1)
End Sub





Aaron Young
Analyst Programmer
adyoung@win.bright.net
aarony@redwingsoftware.com

[Dr_Michael]

I used this useful code. It works and returns the IP address of a specific server giving as input the server name (eg www.yahoo.com)
The problem is that in a specific situation where the server was "down" (I mean it was not connected to Internet because of a network damage), the program continued to find the server and giving the right IP. How is it possible? Are there various levels of ping?
And something important: Trying to ping with this code, it resolved the right IP address, but at exactly the same time, I tried manually to ping by msdos prompt and the server not found (as expected). What's going on???

Michael Vlastos
Automation Engineer
Intracom, Research & Development Division
Development Programmes Department
Athens, Greece

[TCartwright]

All ping is telling you that is that the server's NIC is responding to ICMP requests. That does not mean that the web site is necessarily working. The web site is listening over a socket (typically port 80) and just because you can't load the web page does not mean the server is down. And just because ping is working does not mean the web site is up.

Bottom Line : If ping returns the server is powered up, and configured to return ICMP. It does not mean that anything else is working on the server besides the NIC....

Tim Cartwright 'Will write code for food.
Sr Systems Architect - Information Systems
Splitrock Services Inc.

[Dr_Michael]

Ok I understood but you missed a point: I said that in the same time, I was pinging manually (by MSDOS prompt) and taking NO reply, but besides the application with the code posted here, it's pinging was giving reply!!! How is it possible? And most of all, how can I ping the server correctly, as exactly can be done by MSDOS prompt?

Michael Vlastos
Automation Engineer
Intracom, Research & Development Division
Development Programmes Department
Athens, Greece