Networking LAN and beyond LAB
For this lab you will need to start your host PC and your virtual linux machine
Task 1
Find out what IP address it is using what command? On windows we use ipconfig in linux we use the
term interface :-________________ IP Address ___.___.___.___ with a subnet mask of
___.___.___.___ to find the Default Gateway us the command Route this will list all the routes that
the machine will know._______________________________________________________________
Then check the Host PC what address information do you have for that:- IP Address?___.___.___.___
Subnet mask ? ___.___.___.___ Default Gateway ___.___.___.___
Note that the both IP Addresses have the same first 3 octet information for example 172.16.0.X this
shows that they are on the same LAN the information that confirms this is the Subnet mask
255.255.255.0 in binary this would look like this 11111111.11111111.11111111.00000000 the ‘1’
indicate bits that it belongs to the network, the ‘0’ indicates bits that belongs to the host part of the
address. Note the host part is different in both addresses. write down the network information
___.___.___._0_ the ‘0’indecating all of the host which belong to that network.
If you were to add another PC to the network you would need to do this in (task 4)you will need to
have the same LAN address but with a unique host address.
Test that you can communicate between the two by using the command ping X.X.X.X this will send
continuous ping packets to be sent until you press Ctrl – C on the windows Host it will only send 4
ping packets and will then stop. A reply indicate a successful connection. If it fails check the windows
firewall might need to be turned off for this Lab. If it still fails troubleshoot it write down any
processes you use in your log book.
Task 2
To change the IP Address on the Linux Slackware use the command netconfig this will ask you a few
question 1. Host name? 2. Domain name? 3. Static, DHCP we are going to select Static addresses
Enter the IP address 192.168.10.<the CS number on the top of your screen> then the subnet mask
of:- 255.255.255.0 it will then ask for the default gateway put 192.168.10.100 for the DNS address
put the same address.
Type ifconfig has this changed the IP Address? ___ if so why?________________________________
The network service =rc.inet1what command will you use __________________________________
If you ping the Host PC what happens ___________________________________________________
Type in route do you have a route to the Host PC’s network _________________________________
The command route add will add the correct route (Hint use the man pages)
The Default Gateway is always the interface that can lead to that network, so the physical network
hasn’t changed so both networks can be seen on the same physical network so the gateway can be
your own IP Address. More commonly it would be the internal interface of the router that you are
using.
Now can you ping the Host PC? ___ to check the windows routing table use the command route
print does it have the route to 192.168.10.0? use the help command.
Ping to prove two way communication between both hosts. If it still fails troubleshoot it write down
any processes you use in your log book.
Task 3
On the host PC start the program Wire Shark go to capture select the interface that you want to
monitor the built in NIC eg Realtek or intel
It will then capture all the network packets going through that interface. Stop the capture by the NIC
icon and red stop sign, to the left of that is the start icon. Using the Host PC type in the command at
the command prompt arp –a this will display all known IP Address to
MAC Address information.
To clear this information of all learnt address information type arp –d *
this will remove it. Do the first process again to prove the virtual
machines address has gone. Then type ping the virtual host IP address.
Just before you send the ping, start Wire Shark’s capture. As soon as it has finished stop the capture.
Then review the packets that were captured. Look for your first ping packet (ICMP what does this
stand for?)_________________________________________. What is the packet did you send that
precedes the Ping from you PC _____________________
the Wire Shark screen is split into 3
sections the first show the list of
packets captured. The 2nd is for
searching through the headers to
view the information this
information makes more sense if
you understand the OSI 7 Layer
Model. The 3rd is the raw Data with
the ASCII interpreted for you.
Look at the ARP request what is in
the Destination IP Address?
___.___.___.___ what is the Mac
address __:__:__:__:__:__:__
What is the Source IP Address
___.___.___.___ What MAC
Address __:__:__:__:__:__:__
Now repeat the arp –a command
you should see the Destination MAC Address added to the ARP cache. You can not communicate on
a LAN unless you have the Physical Address eg the MAC Address, this will happen each time you
communicate with a new host try pinging the PC next to you.
Task 4
Using Packet Tracer 5.X start the application. If you do not have this application at home
http://194.83.236.10/PacketTracer5.exe
from the icons in the bottom left-hand corner select end devices click on the PC and then
click on the page. A PC should appear, then select another. To link the PC together click on
the lightning icon connections. The first option is automatically choosing the media to
connect. Click on the first PC and then drag
the line across the second PC with a click.
You should see a black dotted line between
the two devices. This is to show a crossover
cable this is because both devices are DTE’s
and therefore they both transmit on pins one
and two and received on pins three and six.
Therefore a crossover cable connects pins
one and two input to three and six output.
Double click on the first PC
Select the
Desktop tab
click on the IP
configurations icon and put in the IP address of 192.168.5.2 with subnet mask of
255.255.255.0 then opened the second PC and put in 192.168.5.3 with a subnet mask of
255.255.255.0 then close that icon. Open a command prompt icon and type in the ping
command for the other computer. You should receive 4 replies If it works correctly. If you
don’t receive any replies check the IP addresses that they are on the same networks.
Stage two
Add another two computers and connect them all together by using a hub
Configure these two new computers with the same network address as the previous two.
Once you have done this you have a choice between the real time and
simulation click on to simulation and close the window that comes up. To
send a packet the envelope with the + click on that and then click on the
computer that you wished to send the packet and then another PC to
receive the packet then watch what happens
What happened? _______________________________________________
Who received the information?_____________________________________
Why did the other two dropped the packets? __________________________
A hub is a layer 1 device it repeats everything it receives on all ports apart from the one he
received it on. What is the problem with this?____________
Remove the hub by delete in it and then click on a switch and connect to the PCs do the
same procedure as before. What happened?________________
If this is better why?__________________________ a switch is a layer to device and is
therefore able to look at the frames going through the ports and check to see a MAC
address it then looks up on its table of MAC addresses to check to see which port it needs to
be sent out of so therefore is able to route only the information that is required to go to that
port. This is known as segmentation of the network this allows us to increase the traffic that
the network is able to take.
insert another two PCs set their IP address as 172.16.0.3/4 with a subnet mask of
255.255.0.0
Using the desktop tab use the icon to open for a command prompt and ping the other PC.
Did it work? ____ now ping PC 0. did it work?____ what was the reason for this?
___________________________________________
Move the two PCs that are on the 172.16.X.X network on to a separate switch.
Select a router 3rd one in (XM) it has 2
fast Ethernet ports. Then connect the
switches up to the router. Then put the
IP Address that meets the network
address on each interface, this will
become the default gateway for that
network. Test the network by pinging a
PC on the other network using the
command prompt. Why did the first
ping fail? ______________________
Task 5 The Host file and Services File
The beginning of the Internet all network administrators would list all the hosts and IP addresses in a
file the hosts file this was held centrally in the Internet. But as the Internet increased in size this
became unworkable but every PC still has a hosts file and this performs the same function so before
your PC asks a DNS server it checks the host file is stored in/etc/hosts if you go into this file and edit
it so that your IP address, followed by a tab and then the name of your computer, then save it. You
could then in the command line ping the name of your computer and it will ping the IP address you
entered if you enter the IP address and name in the same fashion PCs next to you you will then be
up to ping by name and not use the IP address. Take a screenshot and show this file and the test to
show it works. This file also exists in Windows:- C:\Windows\system 32\drivers\etc\hosts this file
works exactly the same.
The services file is in:-/etc/services look at this file and explain what it contains. Windows has the
same file and is stored in:- C:\Windows\system 32\drivers\etc\services
These files are handy when using network services and tools. With your understanding of the OSI 7
layer model this will help you look at and understand the PDU (packet distribution unit)
in your logbook show the OSI 7 Layer Model explain each layer and then fitted in with the PDU
information.
References
week 4 lecture notes and PowerPoint
Networking Complete Sybex ISBN0-7821-2610-3
IT Essentials chapter 8 http://194.83.236.10/ITEPC_v401/start.html