How Can I Monitor My
Server’s and Networked Device’s Connection Status?
Overview
What
is a Networked Device?
How
do networks work?
Diagram
of OSI Model
Diagram
of Simple Network
What
protocol is used for device status?
What
is ICMP?
What
is a Ping?
How
can I use ICMP to conduct a Ping?
What
is Ping Wizard?
Can
you show me an example of how Ping Wizard works?
[Visual
Basic]
[VBScript]
[Active
Server Pages]
[Visual
C++]
[Visual
FoxPro]
Where
can I find more information about Ping Wizard?
Who
is Seekford Solutions, Inc.?
A lot if time is spent designing
and implementing network designs and setting up devices like computers,
servers, TCP/IP connected equipment and more. Even with the best plans and
architecture there is always the uncertainty of device failure or link failure.
When you have distributed applications or a critical servers and devices, it
becomes that much more important to have a method of monitoring the devices to
see if they are online, alive, and reachable on the network.
This article will explain a rough overview of how networks work, how
devices are connected and how you can write software to monitor them actively.
A networked device can be anything
from a mainframe server, a printer all the way to custom TCP/IP implementing
devices that monitor pump operations and pressure integrity or even display and
communication devices. With regards to this article, a Networked Device is any
hardware that is logically connected to a network, and uses the TCP/IP
communication protocol. This means web servers, personal computers and even
your network enabled coffee machine are considered Networked Devices.
A network is a set of
interconnected devices that can all speak the same language. There are many
different types of networks, Token-ring, IPX, AppleTalk, TCP/IP, and even
proprietary communications used by some PLC’s and other hardware. The scope of
this article will cover TCP/IP networks, but the physical layout is the same
for most types of networks. TCP/IP stands for Transmission Control
protocol/Internet Protocol. The standard network is a combination of Ethernet
and possibly wireless connected communication devices.
Every device that is connected to
the network is considered a node on the network. A device must have a unique
address that identifies it when communicating. This is where IP addresses come.
When the device boots up, it either assumes a preset IP address or request an
open address from a DHCP server. DHCP servers are useful because they assign
open addresses to new devices. No two devices can have the same IP address on
the network otherwise connection problem will occur.
Devices speak on the network using
network interface hardware that has built-in logic for the actual physical
communication. In an Ethernet network, communication takes place in a manner
that is similar to the way a group of friends talk. Each device waits until the
line is quiet, no one is transmitting, and then begins to transmit their own
message. It is possible for two devices to start talking at the same time. This
is detected by the transmitting devices because they listen to the data as it
is sent and if their data is not what they think it should be, they stop
transmitting and wait a random amount of time before checking and transmitting
again. This random time is important because if they waited the same amount of
time, an infinite loop would be created as each of the devices kept colliding.
The network has been described as
using TCP/IP as the basis for communication. The relevant part of that is the
IP or Internet Protocol. This has a subset, which allows for some standard
functionality for communicating with devices. One such functional level is
called ICMP or Internet Control Messaging Protocol.
ICMP, or Internet Control
Messaging Protocol, supports packets containing error, control, and
informational messages. It is a critical part of the Internet Protocol module
and is required to be implemented in all IP stacks. ICMP is used for
transmitting messages about the status of packet sends, network problems and
more. The relevant part of the ICMP that is used for checking if a device is
online is the ECHO command. Traditionally this is called a Ping, since this the
name of the utility from UNIX that utilized the command.
Ping is actually the name of a
utility written by a programmer for the Unix operating system but now has
become synonymous with the ICMP Echo command. A Ping works by sending a special
packet of data to a host machine and then waits for the response. The time it
takes for this response is called the RTT or Return Trip Time. The longer the
time, the worse the network link is between the client and host machines. If
there is no response, then it can be assumed that either the network link has
been broken or the host is not currently online or active.
It is often believed that "Ping"
is an abbreviation for Packet Internet Groper, but Ping's author has stated
that the names comes from the sound that a sonar makes. We tend to like the
Packet Internet Groper since it seems a better techie term.
To implement the ICMP protocol
there are a couple of ways of handling it. The main way is to create a RAW
socket and format a special data packet that is sent using an IP packet to the
host. This can be complicated since it requires a lot of knowledge about how
Sockets work and also about Network byte ordering which is different from the
Intel byte ordering used in most PC’s memory. The easy way of handling a Ping
is to use Ping Wizard. It is an ActiveX control that works in a normal
container application or even in scripted languages like VBScript and Active
Server Pages.
Ping Wizard is an ActiveX control
created by Seekford Solutions, Inc. that makes sending Pings very simple. Only
one line of code is needed to actually issue the Ping. It then provides a lot
of information from the host such as the RTT or Return Trip Time, the TTL, or
Time to Live, and response data provided by the host. Monitoring network
connections becomes incredibly easy with this tool and implementation into your
application is trivial.
Below is source code for a variety
of different programming languages that can use Ping Wizard. If yours is not
listed, then use the code below to provide a guide for your coding.
The source code shows actual use
for the product and possible data manipulation, so some of it may be lengthier
than needed for the simplest functionality.
Dim bOK As String
Dim sCurrentPING As
String
‘PingWzard21 is an Instance of Ping Wizard
Version 2 on the Form
PingWizard21.ResolveNumericIPToHostName = True
‘Set to False for a faster response since the
DNS lookup can take some time
sCurrentPING = “192.168.0.1”
‘Address to Ping
bOK = PingWizard21.PingWithoutRAW(sCurrentPING)
If bOK Then
MsgBox
CStr(PingWizard21.Address) & “ – Connected” & vbCRLF
_
& “Address Name: “ & PingWizardv21.AddressName & vbCRLF
_
& “RTT: “ & CStr(PingWizard21.RTT)
Else
MsgBox
CStr(PingWizard21.Address) & “ –
FAILED” & vbCRLF _
& “Error: “
& PingWizard21.LastErrorDescription
End If
‘ This is a
comprehensive example showing the results like you would see from the PING.EXE
program
set
MyPINGWizard =
CreateObject("PINGWIZARD.PINGWizardCtrl2") ‘Create the
instance of Ping Wizard v2
MyPINGWizard.UnlockPingWizard("")
Dim sData,bIsOk,iIndex,iPacketsSent
,iPacketsReceived ,iPacketsLost ,dAveragems ,iMinms ,iMaxms
dim sMsg
MyPINGWizard.ResolveNumericIPToHostName
= TRUE
For
iIndex = 1 To 4
iPacketsSent =
iPacketsSent + 1
bIsOk =
MyPINGWizard.PingWithoutRAW("www.SeekfordSolutions.com")
If bIsOk Then
iPacketsReceived
= iPacketsReceived + 1
sData
= "Reply from " & MyPINGWizard.Address & "[" &
MyPINGWizard.AddressName & "]: bytes=" & _
CStr(MyPINGWizard.ReplyDataLength) & " time=" &
CStr(MyPINGWizard.RTT) & "ms TTL=" & CStr(MyPINGWizard.TTL)
If (iPacketsSent = 1) Then
iMinms = MyPINGWizard.RTT
Else
iMinms = IIf(iMinms > MyPINGWizard.RTT, MyPINGWizard.RTT, iMinms)
End If
iMaxms
= IIf(iMaxms < MyPINGWizard.RTT, MyPINGWizard.RTT, iMaxms)
dAveragems
= (IIf(iPacketsReceived = 1, MyPINGWizard.RTT, dAveragems) + MyPINGWizard.RTT)
/ 2
Else
iPacketsLost
= iPacketsLost + 1
sData
= "Error! Error number: " & CStr(MyPINGWizard.LastErrorNumber) & "
Error Description: " &
MyPINGWizard.LastErrorDescription
End If
sMSg = smSg & sdata & vbcrlf
Next
smsg = smsg & vbCrLf
& "Ping statistics for " & MyPINGWizard.Address & ":" & vbCrLf
smsg = smsg & "Packets: Sent = " & cstr(iPacketsSent) & ",
Received = " & cstr(iPacketsReceived)
& ", Lost = " & iPacketsLost
& " (" & cstr(((CDbl(iPacketsLost) \
CDbl(iPacketsSent)) * 100)) & "% loss)," & vbCrLf
smsg = smsg &
"Approximate round trip times in milli-seconds:" & vbCrLf
smsg = smsg & vbTab
& "Minimum = " & cstr(iMinms) &
"ms, Maximum = " & cstr(iMaxms) & "ms,
Average = " & cstr(CInt(dAveragems)) &
"ms" & vbCrLf
msgBox sMsg
function
IIF(a,b,c)
if a then
iif = b
else
iif = c
end if
end function
<%
dim sAddressToPing
sAddressToPing = “localhost”
set MyPINGWizard
= Server.CreateObject("PINGWIZARD.PINGWizardCtrl2")
Response.write("Ping Timeout:" + CStr(MyPINGWizard.Timeout)
+ vbcrlf)
Response.write("Ping Packet Size:" + CStr(MyPINGWizard.PacketSize)
+ vbcrlf)
Response.write("PING address:""" + sAddressToPing + """")
Response.write("<HR>")
‘NOTE: YOU WILL NEED A VALID LICENSE TO USE THIS
IN ASP.
MyPINGWizard.UnlockPingWizard("")
Response.flush
Dim sData,bIsOk,iIndex,iPacketsSent
,iPacketsReceived ,iPacketsLost ,dAveragems ,iMinms ,iMaxms
MyPINGWizard.ResolveNumericIPToHostName
= TRUE
‘Set this to False to improve speed
Response.write("Pinging "
& sAddressToPing & " with " & CStr(MyPingWizard.PacketSize)
& " bytes of data:" & vbCrLf & vbCrLf)
For
iIndex = 1 To 4
iPacketsSent =
iPacketsSent + 1
bIsOk =
MyPINGWizard.PingWithoutRaw(sAddressToPing)
If bIsOk Then
iPacketsReceived
= iPacketsReceived + 1
sData
= "Reply from " & MyPINGWizard.Address & "[" &
MyPINGWizard.AddressName & "]: bytes=" & _
CStr(MyPINGWizard.ReplyDataLength)
& " time=" & CStr(MyPINGWizard.RTT) & "ms TTL=" &
CStr(MyPINGWizard.TTL)
If (iPacketsSent = 1) Then
iMinms = MyPINGWizard.RTT
Else
iMinms = IIf(iMinms > MyPINGWizard.RTT, MyPINGWizard.RTT, iMinms)
End If
iMaxms
= IIf(iMaxms < MyPINGWizard.RTT, MyPINGWizard.RTT, iMaxms)
dAveragems
= (IIf(iPacketsReceived = 1, MyPINGWizard.RTT, dAveragems) + MyPINGWizard.RTT)
/ 2
Else
iPacketsLost
= iPacketsLost + 1
sData
= "Error! Error number: " & CStr(MyPINGWizard.LastErrorNumber)
& " Error Description: " &
MyPINGWizard.LastErrorDescription
End If
Response.write(sData
& vbCrLf)
Next
Response.write( vbCrLf
& "Ping statistics for " & MyPINGWizard.Address & ":" & vbCrLf)
Response.write("Packets:
Sent = " & cstr(iPacketsSent) & ",
Received = " & cstr(iPacketsReceived)
& _
", Lost = " & iPacketsLost & " (" & cstr(((CDbl(iPacketsLost)
\ CDbl(iPacketsSent)) * 100)) & "% loss),"
& vbCrLf)
Response.write("Approximate
round trip times in milli-seconds:" & vbCrLf)
Response.write(vbTab &
"Minimum = " & cstr(iMinms) & "ms,
Maximum = " & cstr(iMaxms) & "ms,
Average = " & cstr(CInt(dAveragems)) &
"ms" & vbCrLf)
%>
Assumptions:
m_PingWizard is a member variable for an Instance of Ping Wizard v2 on a
dialog
m_Response is a member variable for a textbox on a dialog.
Code:
char buff[20];
int iPacketsSent = 0;
int iPacketsReceived = 0;
int iPacketsLost =0;
double dAveragems =0;
int iMinms =0;
int iMaxms =0;
m_PingWizard.UnlockPingWizard("");
m_PingWizard.SetPacketSize(atol(m_PacketSize));
m_PingWizard.SetTimeOut(atol(m_TimeOut));
m_PingWizard.SetResolveNumericIPToHostName(m_ResolveNumeric);
m_Response = "Pinging " + m_AddressToPing + " with " + m_PacketSize + "
bytes of data:\r\n\r\n";
for(int iIndex =0;iIndex <4;iIndex++)
{
iPacketsSent++;
if (m_PingWizard.PingWithoutRAW(m_AddressToPing))
{
m_Response += "Reply from " + m_PingWizard.GetAddress() + "[" +
m_PingWizard.GetAddressName() + "]: bytes=";
_itoa(m_PingWizard.GetReplyDataLength(),buff,10);
m_Response += CString(buff) + " time=";
_itoa(m_PingWizard.GetRtt(),buff,10);
m_Response += CString(buff) + "ms TTL=";
_itoa(m_PingWizard.GetTtl(),buff,10);
m_Response += CString(buff) + "\r\n";
iPacketsReceived++;
if (iPacketsReceived ==1)
{
iMinms = m_PingWizard.GetRtt();
}else
{
iMinms = (iMinms > m_PingWizard.GetRtt()) ? m_PingWizard.GetRtt() :
iMinms;
}
iMaxms = (iMaxms > m_PingWizard.GetRtt()) ? iMaxms :
m_PingWizard.GetRtt();
dAveragems += m_PingWizard.GetRtt();
}else
{
_itoa(m_PingWizard.GetLastErrorNumber(),buff,10);
m_Response += m_PingWizard.GetLastErrorDescription() + "\r\n"
;
iPacketsLost++;
}
}
dAveragems /= iPacketsReceived;
m_Response += "Ping statistics for " + m_PingWizard.GetAddress() + "
:\r\n";
_itoa(iPacketsSent,buff,10);
m_Response += "Packets: Sent = " + CString(buff) + ", Received = ";
_itoa(iPacketsReceived,buff,10);
m_Response += CString(buff) + ", Lost = ";
_itoa(iPacketsLost,buff,10);
m_Response += CString(buff) +" (";
_itoa(((double)iPacketsLost / (double)iPacketsSent) * 100,buff,10);
m_Response += CString(buff) + "% loss),\r\n";
m_Response +=
"Approximate round trip times in milli-seconds:\r\n";
_itoa(iMinms,buff,10);
m_Response += "\tMinimum = " + CString(buff) + "ms, Maximum = ";
_itoa(iMaxms,buff,10);
m_Response += CString(buff) + "ms, Average = ";
_itoa((int)dAveragems,buff,10);
m_Response += CString(buff) + "ms\r\n";
AfxMessageBox(m_Response);
Assumptions:
That a dialog has the PingWizardv2
object on it name MyPINGWizard or that the createobject command is used.
Code:
&& set MyPINGWizard
= CreateObject("PINGWIZARD.PINGWizardCtrl2")
&& Uncomment the above line of code and remove the THISFORM ids
if you want to create the object at runtime
THISFORM.MyPINGWizard.UnlockPingWizard("")
THISFORM.MyPINGWizard.ResolveNumericIPToHostName
= .t.
local sData,bIsOk,iIndex,iPacketsSent
,iPacketsReceived ,iPacketsLost ,dAveragems
sData = ""
bIsOk = .f.
iIndex = 0
iPacketsSent = 0
iPacketsReceived = 0
iPacketsLost = 0
dAveragems = 0
iMinms = 0
iMaxms = 0
sMsg = ""
dPacketLoss =0
For
iIndex = 1 To 4
iPacketsSent =
iPacketsSent + 1
bIsOk =
THISFORM.MyPINGWizard.PingWithoutRaw("www.SeekfordSolutions.com")
If bIsOk Then
iPacketsReceived
= iPacketsReceived + 1
sData
= "Reply from " + THISFORM.MyPINGWizard.Address + "[" +
THISFORM.MyPINGWizard.AddressName + "]: bytes=" +
STR(THISFORM.MyPINGWizard.ReplyDataLength) + " time=" +
STR(THISFORM.MyPINGWizard.RTT) + "ms TTL=" + STR(THISFORM.MyPINGWizard.TTL)
If (iPacketsSent = 1) Then
iMinms = THISFORM.MyPINGWizard.RTT
Else
iMinms = IIf(iMinms > THISFORM.MyPINGWizard.RTT, THISFORM.MyPINGWizard.RTT,
iMinms)
EndIf
iMaxms
= IIf(iMaxms < THISFORM.MyPINGWizard.RTT, THISFORM.MyPINGWizard.RTT, iMaxms)
dAveragems
= (IIf(iPacketsReceived = 1, THISFORM.MyPINGWizard.RTT, dAveragems) +
THISFORM.MyPINGWizard.RTT) / 2
Else
iPacketsLost
= iPacketsLost + 1
sData
= "Error! Error number: " + STR(THISFORM.MyPINGWizard.LastErrorNumber) + "
Error Description: " +
THISFORM.MyPINGWizard.LastErrorDescription
EndIf
sMSg = smSg + sdata + + chr(13)
Next
if
(ipacketslost >0) then
dPacketloss = ((iPacketsLost) / (iPacketsSent)) * 100
endif
smsg = smsg + chr(13) +
"Ping statistics for " + THISFORM.MyPINGWizard.Address
+ ":" + chr(13)
smsg = smsg + "Packets:
Sent = " + STR(iPacketsSent) + ", Received = "
+ STR(iPacketsReceived) + ", Lost = " +
STR(iPacketsLost) + "(" + STR(dPacketLoss)
+ "% loss)," + chr(13)
smsg = smsg + "Approximate
round trip times in milli-seconds:" + STR(dAveragems) + chr(13)
smsg = smsg + "
" + "Minimum = " + STR(iMinms) + "ms,
Maximum = " + STR(iMaxms) + "ms, Average = " +
(STR(dAveragems)) + "ms" + +
chr(13)
messageBox( sMsg)
More information can be found at
the product’s web link:
http://www.seekfordsolutions.com/Products/PingWizard/
Seekford Solutions, Inc. is a
software development corporation specializing in the design and development of
state of the art ActiveX controls and custom projects. Their core product line
is focused on Internet technologies primarily in the facilitation of the use of
the common Internet protocols. The design philosophy is based on ease of use
and quick implementation time. They also handle custom projects for clients who
are need of specialty software or who need a framework base to use. The company
was founded in early 2001.
Their website is
http://www.seekfordsolutions.com/
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