How Can I Trace The Path Of A Network Packet?
Overview
What
is a network?
How
does a network work?
What
is a router?
Network
Path Diagram.
How
can I trace the path?
What
is TraceRoute Wizard?
Can
I see Sample code:
[Visual
Basic]
[VBScript]
[Visual
FoxPro]
[Visual
C++]
[Active
Server Pages]
Where
can I find TraceRoute Wizard?
Who
is Seekford Solutions, Inc.?
A lot of people really don’t
understand how networks work or how their data gets from their computer to
another computer and back again. This article will discuss how data packets
move through a network and why you should understand how your network is setup
and how it works.
A network literally defined is a
“system of computers, terminals, and databases connected by communications
lines.” A network is a group of computers than exchange data between themselves
using some sort of method for communication. Networks used to normaly be
connect via IPX using cable lines attached directly to each computer with a
terminator at the end. Now Ethernet networks are the most dominant as well as
the addition of the WiFi connection methods for wireless access. To get data
from one point of the network to another there needs to exist some sort of
rules for the transmission of data over the physical layer.
Hardware handles the difficult
task of transmitting the bits and information of the communication mediums but
their still is the need for the data to leave the local network of computers
and connect with all the other networks. This is currently done using the IP
protocol for data communication. Each computer is setup to have a unique ID
number that is used for identification of a particular machine. The IP packets
are formatted with the ID number of the target, the sender, and also the port
number that it is destined to go to. Ports are different points at which a
client can connect which allows a single machine to accept multiple requests
from multiple clients at the same time. The IP packets are first sent across
the local network to see if that network ID, or IP address, is located on the
local network. If not, then it is up to a piece of hardware called a router to
take over the sending of the packet.
A router is a piece of hardware
with a complicated piece of software called firmware that handles all the hard
work of moving packets of data where they need to go. The router looks at
packets and decides if they need to leave the local network. If it thinks they
belong to an IP address somewhere else they attempt to deliver it by sending it
to the next router in the path to the recipient until the last router in the
path can directly deliver the message. Every time a packet has to go through a
router, the time it takes to reach its target is increased. If a router is
overloaded by a lot of traffic, they can actually drop, or discard, packets. It
is then up to the higher level communications protocol to resend the packet
again. This makes it more obvious that the more points your packet has to go
through to get to the final destination, the longer it will take due to slow
routers, overloaded routers, or the mere processing time of the routers.
How
can I trace the path?
There is really only one good way
to trace the path of a packet and that is to trick each router on the path the
packet takes into thinking it needs to tell the sender there was an error in
communication. The best and most common way is to attempt to ping the target
host’s IP address using and incremental Time to Live identifier in the IP
header. The TTL or Time to Live identification is used to tell routers how many
times the packet can be routed before it should just be thrown away and
discarded. Every router is considered a hop, and every hop the TTL value is
decremented by one. Once it reaches 0 the router that has it discards the
packet and then sends an ICMP control message back to the caller telling it
that the packet timed out and did not reach the destination. Some routers are
not courteous enough to respond with the ICMP control message; these routers
are called “black hole router” due to the fact packets go in but may not come
out. To find out each router a packet goes through and effectively determine
the number of hops it must take requires a simplistic algorithm of sending a
special packet with a TTL of 1 and incrementing it to N which is the value TTL
is when you reach the target. This algorithmic process is called a Trace Route.
A program that comes with Windows called TraceRt.exe is very familiar to
a lot of network administrators because it does exactly what was just
described. Developers can add this functionality to their programs using an
ActiveX control called TraceRoute Wizard.
TraceRoute Wizard is an ActiveX
control that enables developers to conduct Trace Routes using their network to
determine the number of hops a packet must take. This is great for determining
which routers are performing poorly, the number of hops a packet is taking out
your network and through an ISP’s network and more. It is also good for
developers because they can show why their program may not be communicating as
quickly as they would like due to network congestion. You could give the IT
department a list of all the routers your communicating through and show them
that they need to upgrade their network or change ISP’s. The control provides
the Return Transmit Time for each packet and the IP addresses and host names
for each hop the packet takes to its destination.
txtTraceData.Text = "Tracing route
to " & txtTraceAddress.Text & vbCrLf & "over a maximum of " &
CStr(TraceRouteWizard1.MaxHops) & " hops:" & vbCrLf &
vbCrLf
txtTraceData.Text
= txtTraceData.Text & "Hop" & vbTab & "#1" & vbTab & "#2"
& vbTab & "#3" & vbTab & "Host IP/Name" & vbCrLf
txtTraceData.Refresh
TraceRouteWizard1.ResolveIPsToHostNames
= CBool(chkResolveNumericIP)
TraceRouteWizard1.HopTimeOut
= CInt(txtTimeout)
TraceRouteWizard1.PacketSize
= CInt(txtPacketSize)
UsingStepTrace
= True
Dim
i As Integer
Dim
x As Integer
Dim
sAddress As String
If
(TraceRouteWizard1.StepTraceTo(txtTraceAddress.Text)) Then
Do
i = i + 1
txtTraceData.Text = txtTraceData.Text & CStr(i)
& vbTab
sAddress = ""
txtTraceData.Refresh
DoEvents
If (TraceRouteWizard1.HopSuccessful(i))
Then
For x = 1 To
TraceRouteWizard1.HopAttempts
txtTraceData.Text = txtTraceData.Text & IIf(TraceRouteWizard1.HopAttemptSuccessful(i,
x), TraceRouteWizard1.HopRTT(i, x), "---") & " ms" & vbTab
If Len(TraceRouteWizard1.HopAddress(i,
x)) > 0 Then
sAddress = TraceRouteWizard1.HopAddressName(i, x) & " [" &
TraceRouteWizard1.HopAddress(i, x) & "]"
End If
Next
txtTraceData.Text = txtTraceData.Text & sAddress & vbCrLf
Else
txtTraceData.Text = txtTraceData.Text &
TraceRouteWizard1.HopLastErrorDescription(i) & vbCrLf
End If
Loop Until Not (TraceRouteWizard1.StepTraceNext)
Else
txtTraceData.Text = txtTraceData.Text & "1" & vbTab &
TraceRouteWizard1.LastErrorDescription & vbCrLf
End
If
txtTraceData.Text
= txtTraceData.Text & vbCrLf & "Trace complete." & vbCrLf
UsingStepTrace
= False
function
IIF(a,b,c)
if a then
IIF = b
else
IIF = c
end if
end
function
dim sIP
dim MyTraceRouteWizard
dim bResolveHostNames
dim sResults
'create the object
set MyTraceRouteWizard
= CreateObject("TRACEROUTEWIZARD.TraceRouteWizardCtrl2")
sIP = InputBox("Please enter the
host to trace: i.e. www.SeekfordSolutions.com or 192.168.0.2","Host to Trace
Path To", "www.SeekfordSolutions.com")
bResolveHostNames = InputBox("Do you
want to resolve IP addresses into Hostnames? This may take a lot longer. Enter
Y to resolve, otherwise enter anything else.","Resolve Host Names?","Y")
if ( bResolveHostNames = "Y")
then
MyTraceRouteWizard.ResolveIPsToHostNames
= TRUE
else
MyTraceRouteWizard.ResolveIPsToHostNames
= FALSE
end if
msgbox "We are going to Trace now,
Please be patient. This could take up to a minute or so depending on network
conditions and whether you chose to Resolve Host Names"
MyTraceRouteWizard.UnlockTraceRouteWizard("")
Dim sData,bIsOk,iIndex,iPacketsSent
,iPacketsReceived ,iPacketsLost ,dAveragems ,iMinms ,iMaxms
Dim i
Dim
x
dim sAddress
If
(MyTraceRouteWizard.StepTraceTo(sIP)) Then
Do
i = i +
1
sResults
= sresults & CStr(i) & vbTab
sAddress
= ""
If (MyTraceRouteWizard.HopSuccessful(i)) Then
For x = 1 To
MyTraceRouteWizard.HopAttempts
sResults = sresults & IIf(MyTraceRouteWizard.HopAttemptSuccessful(i,
x), MyTraceRouteWizard.HopRTT(i, x), "---") & " ms" & vbTab
If Len(MyTraceRouteWizard.HopAddress(i,
x)) > 0 Then
sAddress = MyTraceRouteWizard.HopAddressName(i, x) & " [" &
MyTraceRouteWizard.HopAddress(i, x) & "]"
End If
Next
sResults =
sresults & sAddress & vbCrLf
Else
sResults =
sresults & MyTraceRouteWizard.HopLastErrorDescription(i) & vbCrLf
End If
Loop Until Not (MyTraceRouteWizard.StepTraceNext)
Else
sResults =
sresults & "1" & vbTab & MyTraceRouteWizard.LastErrorDescription
& vbCrLf
End
If
sResults = sresults & vbCrLf & "Trace complete. Please visit
www.SeekfordSolutions.com to Purchase!" & vbCrLf
msgbox sResults
local
vbCRLF
local
vbTab
THISFORM.UsingStepTrace
= .t.
vbCRLF = chr(10)
vbTab = chr(9)
THISFORM.txtTraceData.value
= "Tracing route to " + TRIM(THISFORM.txtTraceAddress.value)
+ vbCrLf + "over a maximum of " + Str(THISFORM.TraceRouteWizard.MaxHops)
+ " hops:" + vbCrLf + vbCrLf
THISFORM.txtTraceData.value
= THISFORM.txtTraceData.value + "Hop" +
vbTab + "#1" + vbTab + "#2" + vbTab + "#3" + vbTab + "Host IP/Name" + vbCrLf
THISFORM.txtTraceData.Refresh
THISFORM.TraceRouteWizard.ResolveIPsToHostNames
= (THISFORM.chkResolve.value
=1)
THISFORM.TraceRouteWizard.HopTimeOut
= VAL(STR(THISFORM.txtTimeout.value))
THISFORM.TraceRouteWizard.PacketSize
= VAL(STR(THISFORM.txtPacketSize.value))
THISFORM.TraceRouteWizard.MaxHops
= VAL(STR(THISFORM.txtMaxHops.value))
THISFORM.TraceRouteWizard.HopAttempts
= VAL(STR(THISFORM.txtHopAttempts.value))
THISFORM.UsingStepTrace
= .t.
local
i
local
x
local
sAddress
local
bGoAgain
bGoAgain
= .t.
sAddress
= ""
i
= 0
x
= 0
If
(THISFORM.TraceRouteWizard.StepTraceTo(TRIM(THISFORM.txtTraceAddress.value)))
Then
Do while (bGoAgain)
i = i + 1
THISFORM.txtTraceData.value
= THISFORM.txtTraceData.value
+ STR(i) + vbTab
sAddress = ""
THISFORM.txtTraceData.Refresh
DoEvents
If (THISFORM.TraceRouteWizard.HopSuccessful(i))
Then
For x = 1 To
THISFORM.TraceRouteWizard.HopAttempts
if(THISFORM.TraceRouteWizard.HopAttemptSuccessful(i,
x)) then
THISFORM.txtTraceData.value
= THISFORM.txtTraceData.value
+ STR(THISFORM.TraceRouteWizard.HopRTT(i,
x)) + " ms" + vbTab
else
THISFORM.txtTraceData.value =
THISFORM.txtTraceData.value +
"---" + " ms" + vbTab
endif
If Len(THISFORM.TraceRouteWizard.HopAddress(i,
x)) > 0 Then
sAddress = THISFORM.TraceRouteWizard.HopAddressName(i,
x) + " [" + THISFORM.TraceRouteWizard.HopAddress(i,
x) + "]"
EndIf
Next
THISFORM.txtTraceData.value
= THISFORM.txtTraceData.value
+ sAddress + vbCrLf
Else
THISFORM.txtTraceData.value
= THISFORM.txtTraceData.value
+ THISFORM.TraceRouteWizard.HopLastErrorDescription(i)
+ vbCrLf
EndIf
bGoAgain = THISFORM.TraceRouteWizard.StepTraceNext
enddo
Else
THISFORM.txtTraceData.value
= THISFORM.txtTraceData.value
+ "1" + vbTab + THISFORM.TraceRouteWizard.LastErrorDescription
+ vbCrLf
EndIf
THISFORM.txtTraceData.value
= THISFORM.txtTraceData.value
+ vbCrLf + "Trace complete." + vbCrLf
THISFORM.UsingStepTrace
= .f.
UpdateData(TRUE);
m_bStepTracing= TRUE;
m_TraceRouteWizard.UnlockTraceRouteWizard("");
m_sReplyData.Format("Tracing route to %s\r\nover a maximum of %d
hops:\r\n\r\n",m_sAddress,m_iMaxHops);
UpdateData(FALSE);
m_TraceRouteWizard.SetResolveIPsToHostNames(m_bResolve);
m_TraceRouteWizard.SetHopTimeOut(m_iTimeout);
m_TraceRouteWizard.SetPacketSize(m_iPacketSize);
m_TraceRouteWizard.SetMaxHops(m_iMaxHops);
m_TraceRouteWizard.SetHopAttempts(m_iHopAttempts);
int iHopNumber =0;
int x = 0;
CString sAddress;
if(m_TraceRouteWizard.StepTraceTo(m_sAddress))
{
do
{
iHopNumber++;
m_sReplyData.Format("%s%d\t",CString(m_sReplyData),iHopNumber);
RedrawWindow();
Sleep(0);
if (m_TraceRouteWizard.GetHopSuccessful(iHopNumber))
{
for(x = 1; x <=
m_TraceRouteWizard.GetHopAttempts(); x++)
{
if(m_TraceRouteWizard.GetHopAttemptSuccessful(iHopNumber,x))
{
m_sReplyData.Format("%s%d\t",CString(m_sReplyData),
m_TraceRouteWizard.GetHopRTT(iHopNumber,x));
sAddress.Format("%s
[%s]",m_TraceRouteWizard.GetHopAddressName(iHopNumber,x),m_TraceRouteWizard.GetHopAddress(iHopNumber,x));
}else
{
m_sReplyData += CString("---\t");
}
}
m_sReplyData.Format("%s%s\r\n",CString(m_sReplyData),sAddress);
}else
{
m_sReplyData.Format("%s%s\r\n",CString(m_sReplyData),m_TraceRouteWizard.GetHopLastErrorDescription(iHopNumber));
}
UpdateData(FALSE);
}
while(m_TraceRouteWizard.StepTraceNext());
}else
{
m_sReplyData.Format("%s1\t%s\r\n",CString(m_sReplyData),m_TraceRouteWizard.GetLastErrorDescription());
}
m_sReplyData += CString("\r\nTrace complete.\r\n");
UpdateData(FALSE);
RedrawWindow();
m_bStepTracing= FALSE;
if
request.form("p_Address") <> "" then
set MyTraceRouteWizard
= Server.CreateObject("TRACEROUTEWIZARD.TraceRouteWizardCtrl2")
Response.write("Trace Route Address:""" + request.form("p_Address") +
"""" + vbcrlf)
Response.write("Resolve Host names:""" +
request.form("p_ResolveHostnames") + """" + vbcrlf)
if (
request.form("p_ResolveHostNames") = "TRUE") then
MyTraceRouteWizard.ResolveIPsToHostNames
= TRUE
else
MyTraceRouteWizard.ResolveIPsToHostNames
= FALSE
end if
Response.write("<HR>")
'/////////////////////////////////////////////////////////////
'//
'//
This component will only work in ASP once it has been purchased.
'//
'/////////////////////////////////////////////////////////////
MyTraceRouteWizard.UnlockTraceRouteWizard("")
Response.flush
Dim sData,bIsOk,iIndex,iPacketsSent
,iPacketsReceived ,iPacketsLost ,dAveragems ,iMinms ,iMaxms
Dim i
Dim
x
Dim
sAddress
If
(MyTraceRouteWizard.StepTraceTo(request.form("p_Address")))
Then
Do
i = i +
1
Response.write(
CStr(i) & vbTab)
sAddress
= ""
If (MyTraceRouteWizard.HopSuccessful(i)) Then
For x = 1 To MyTraceRouteWizard.HopAttempts
Response.write(IIf(MyTraceRouteWizard.HopAttemptSuccessful(i, x),
MyTraceRouteWizard.HopRTT(i, x), "---") & " ms" & vbTab)
If Len(MyTraceRouteWizard.HopAddress(i, x)) > 0
Then
sAddress = MyTraceRouteWizard.HopAddressName(i, x) & " [" &
MyTraceRouteWizard.HopAddress(i, x) & "]"
End If
Next
Response.write( sAddress & vbCrLf)
Else
Response.write( MyTraceRouteWizard.HopLastErrorDescription(i) & vbCrLf)
End If
Loop Until Not
(MyTraceRouteWizard.StepTraceNext)
Else
Response.Write(
"1" & vbTab & MyTraceRouteWizard.LastErrorDescription & vbCrLf)
End
If
Reponse.Write( vbCrLf &
"Trace complete." & vbCrLf)
else
Response.write("To trace a route to a host, please enter one below and
click submit.")
end if
TraceRoute Wizard is publicly
available from Seekford Solutions, Inc. on their website @
http://www.SeekfordSolutions.com/Products/
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.
|