CMP2007M – Networks and Network Systems Workshop 4
Outline
In this workshop we are going to look at setting up local ‘private’ networks and see the effect this has on the ability to ping and monitor packets going through that network.
There are four routers available for this session, so you will need to make sure you coordinate in groups of between 8 – 10 people. Remember the cables we made last week? You’re going to need these now for this task.
NOTE: Please ensure that at the end of the workshop you take 10 minutes to put everything back to the way you found it at the beginning…
Task 1 – Checking the Default
Find come fellow students and form a group of 8 or so people, and find a bank of 8 computers.
– As with one of our earlier workshops, remove the firewall ‘ping’ restrictions.
– Record your own IP address and that of all the other machines in your group.
– Ping all the machines in your group and write down which ones provide a reply.
o Make sure you log all this information
Task 2 – Setting up your own network
On the bank of 8 machines you are using, disconnect the Ethernet network cable from the back of the machine, using one of the switches provided in the workshop, and your ‘straight through’ network cables you made, connect all the machines to the switch.
– Now repeat Task 1 above, do you notice anything different? Have the IP addresses changed? Can you still ping?
– Now type the following in to the Command Prompt: ipconfig /renew
– Repeat Task 1 above again…
Task 3 – Configuring your network
We now have to configure our network manually as there is no DHCP server and so the computers need to be given a manual IP address. Go to the Windows Control Panel and click on Networks and Network and Sharing Centre. Click on ‘Change Adapter Settings’ and right click on the Local Area Connection device.
Clicking -> Properties -> Internet Protocol Version 4 -> Properties, use the following settings:
CMP2007M – Networks and Network Systems Workshop 4
Where *** is a unique value for each of the machines on your own network.
Make sure to click ‘validate settings upon exit’. Once you’ve completed this, run the command ipconfig from the command prompt to make sure your settings have been set.
– Complete Task 1 above again, checking to see if you notice any differences.
– Now change the IP Addresses on one of the machines to the SAME IP Address of another machine, so that TWO computers on your network share the EXACT same IP Address.
– What happens if these two computers try to ping each other?
– What happens when another machine on the network tries to ping one of the computers with a duplicate IP?
– Using Wireshark, experiment with monitoring the Ping packet (ICMP) that go to and from each of the machines on the network as you ping. Can you see them from ALL machines?
Task 4 – Private Networks
CMP2007M – Networks and Network Systems Workshop 4
Now we’ve seen that ALL the computers on this network can ping and see each other, but (for example as seen in the assignment) we wish for two distinct networks so that we can restrict traffic.
Network 1:
– Use the following settings to create the first network
IP Address 192.168.1.1 IP Address 192.168.1.2 IP Address 192.168.1.3 IP Address 192.168.1.4
Subnet Mask: 255.255.255.0
Network 2:
– Use the following settings to create the second network
IP Address 192.168.10.1 IP Address 192.168.10.2 IP Address 192.168.10.3 IP Address 192.168.10.4
Subnet Mask: 255.255.255.0
– Now run Task 1 above again, can the machines on Network 1, ping the machines on network 2?
– Using Wireshark, can you see the machines on the other network? i.e. can Wireshark on Network 1 see machines on Network 2?
Once you’ve completed this task, on ALL the machines, change the subnet mask to: 255.255.0.0, now what happens???
Please ensure you put all the computers back to how they were first setup before the workshop started.
End of Workshop