13 July 2015
Lesson Plan for Network Basics Lecture
Part I
Cover Sheet
Lesson Title: Network Basics
Resource Person:
Teaching Method: combined methods of Informal Lecture and Game
References:
- Notes from hackerhigh
- Notes from Adam and Allison
- Network basics from oracle:
- Wikipedia:
Aids/Handouts/Note takers: kali Linux, pencil and paper (or just have them come up in groups and type in their design into notepad), a server set up for the class so the one part groups can send data/sniff the data themselves and another part so 2 groups can sniff each other
Presentation Time: ? minutes
Part 1A
Cognitive Objective: The objective of this lesson is for each student to comprehend the basic concepts of networks and be able to both read and create a packet trace, along with some of the basic concepts of different protocols.
Cognitive Samples of Behavior:
- What is a network, and why is it important?
- How do computers communicate to each other, and how do they communicate to each other over a network?
- What are protocols?
- What are packets?
Affective Objective: The objective of this lesson is for each student to respond with their ideas of what a network is, what packets are, what some of the protocols used for networks are, and to be able to perform simple packet tracing, along with being able to solve problems that have a packet trace (ctf).
Affective Samples of Behavior:
- Openly have discussion of what a network is
- Explain details of what a network is, how it works, and some of the protocols for it
- Have a few examples/activities students work on in groups to complete
Part IB
Organizational Pattern: Topical
Strategy:Present this lesson using the informal lecture and game methods to help students logically follow the flow of the lesson. The groups can be in sets of 2-5 people, depending on the activity, example, and also the number of students. Discuss and define what a network is, some of its protocols, and what packets are. The lesson will start with the class breaking up into groups, and the groups trying to design their own networks (on paper). After designing their networks, we will have a discussion on what they think networks are and how they work. Next, if the basics haven’t been discussed, we will go over those, along with some of the basic protocols and what packets are. The students will then work with their groups and simulate a simple client and a simple server (using code I made during networks class or using Adam/Allison’s code) and send simple packets of data to each other. Afterward, you will go through a simple example of wireshark and explain the steps of how to use it while going through it. Finally, the groups will then play around with wireshark by trying to first intercept packets from their group’s client and server, and then from another group’s.
Lesson Outline:
MP1. Group designing their own network
MP2. Discussion of what they think networks are/how they work
MP3. Defining what the network basics are, along with what some protocols they use are and what packets are
MP4. Video of how packets go through the network
MP5. Example of a packet trace with and without wireshark along with step by step instructions of how to use it
MP6. Group works on tracing their own packets, and then the packets of another group
Part II
Teaching Part
Introduction
Attention: There are many different networks out there, some complex, some simple. Almost everywhere you go you will see a network of some type.
Motivation: A lot of jobs revolve around networks, from IT jobs, to gaming companies, almost every business now-a-days revolves around networks.
Overview: During this lecture, we will explore computer networks. We will do an activity where you design your own networks, and explain why you designed them the way you did. We will have a discussion about what you all think some network basics are, and then we’ll get an explanation of what some basics are, along with some of the protocols they use. Then we’ll take a look at a program to trace packets, and then we’ll use that program to both trace our networks and another group’s network.
Transition:With that said, let’s jump into the group design stage now.
Body
MP1. Group Design
For this activity, please break up into groups. Next, brainstorm a design for a network as you see it (it’s ok if you don’t know about networks right now as we’ll discuss them in a little bit). (Note: give them about 10-15 minutes for this.)
Transition:Ok, now that we’ve made a basic network, let’s discuss what we think some of the network basics are.
MP2. Discussion of networks
Does anyone have any ideas what some of the network basics are? Also, why do we need networks? (Note: Look around the room and pick a few people whose hands are raised, and right down what they say either in notepad or on paper on the overhead.)
Transition:Alright, those are some good ideas, let’s see some of the basics and see what we don’t have here.
MP3. Defining Network basics, protocols, and packets
What does networking mean in computer talk? Well, networking is connecting multiple (2 or more) computers together with the purpose of sharing data. It consists of end devices (computers, cars, mp3 players, cell phones, etc.), routers, and wires that connect end devices to routers and routers to routers. There are multiple types of networks. Here are a few terms for networks you’ll hear: LAN, WIFI, and WAN.
LAN stands for local area network, and is usually used privately. An example of this would be you have a LAN at home that you play multiplayer games with your friends, each on their own tv/ps4 connected by the same router. You aren’t playing over the internet, but rather on the LAN. Everyone on a LAN connects to the internet through the same router (or access point).
WIFI is a version of LAN, and can be used privately or be open to the public, depending on whether you broadcast it or not. All those on the WIFI network connect to the internet through the same access point/router just like with a LAN.
WAN stands for wide area network, and is usually used by big businesses or government agencies.
Here are some pictures to illustrate a LAN and WAN. (Note: Show the LAN and WAN slides on PowerPoint.)
You may be wondering what the purpose of routers is. Well, before we can talk about routers, we must talk about how end devices communicate.
(Note: For this example, draw out a simple network, consisting of a computer, a router, a server – Microsoft in this case --, and the wires connecting them together. Illustrate the packets going to the server, and from the server to the client.)
Let’s say you have windows 8, and it wants an update. The first thing it will do is send a request to Microsoft asking if there are any updates. Next, Microsoft will send a response back saying whether there is one or not. For our example, let’s say there is an update. Now that the computer knows it needs an update, it sends another request to Microsoft asking if it can have the update. Microsoft then sends the update, and then the computer is happy since it is up to date. Now, let’s take this example apart and see what is going on under the hood. This will get a little geeky, but bear with me.
To send a request, the computer sends out a packet, which is a unit of data. It contains the data the computer wants to send to the receiver (in this case a question asking if it needs an update along with what update version it has), as well as the address of the receiver (called the IP address). Now, in order to send it to the receiver, it has to give it to one or more routers first, and the router directs it where it needs to go. (Basically a router is a device that stores information of what computers or routers are at what IP address, and forwards packets to the specific address based on the address the packet has for the destination.)
Once the receiver (in this case Microsoft) gets the packet, it looks at the data, sees the question, gets an answer based on the update info the computer sent, and sticks it in a packet along with the address of the computer, and sends it back. Again the packet goes through the router and then gets sent to the computer. The computer reads the response (in this case that it needs to update), and then sends another packet asking for the update. Microsoft gets the request for the update, and then sends the update. The computer gets the update and then is happy it is up to date. Now, if this was a perfect world you could just send the update all in one packet and be done, but there are size restrictions between routers and wires, so Microsoft has to split up the update into multiple packets and send them all to the computer.
But wait, how do they know to break up the file into several packets? And how do they know where to send it? Well, networks have certain rules called protocols that it follows. There are quite a bit of them, but since this is a short class, we’ll just list off a few. There is the TCP/IP, which is 2 protocols named together. TCP stands for transmission control protocol, which is used to provide a flow of data between computers. IP stands for internet protocol, and is responsible for routing the data across network boundaries.
TCP/IP is comprised of multiple layers. Each layer is designed to do one task and only one task. The reason for this is that the people who designed the layers wanted them to be as simple and effective as possible, while being able to run as fast as possible.
There are 5 layers in the TCP/IP network layout. Here is an image of the layers. Let’s go over a simple explanation of each one.
First up is the Application layer. This layer is the layer that runs programs like Firefox and chrome, and is where the protocols that they use are made at. Some of the protocols used are HTTP, FTP, and SMTP.
The next layer is the transport layer. This layer is responsible for protocols that let the source device to talk to the destination device. There are 2 main protocols here, TCP and UDP.
The next layer is the network layer. This layer is responsible for sticking the data packets create from the previous 2 layers into a datagram that is sent along all the nodes between the source and destination. Basically it has protocols here that tell it how to pack them up, as well as how to send them to each node, and where to go when it gets to each node. The main protocol here is IP (there are others, but we only need to talk about IP here).
The next to last layer is the data layer. This layer is in charge of protocols that allow packets to work with network hardware like switches and routers. Some of the many protocols here are the PPP and Frame Relay.
Finally, the last layer is the physical layer. This layer is the physical method of transportation for the packets, i.e. the wires, cables, and radio waves used. This is where standards for those transportation methods are defined.
And here is an example of how the layers work using a real world problem.
There are other protocols, but it would take quite a bit of time to go over them all, so just remember that there are rules to break up the data files into smaller packets, and then rules that say how big they can be, where to send them, and checks in place to make sure they get there.
Transition: Alright, let’s do an activity where you make your own example of the network layers.
MP4. Group Activity 2
For this activity each group will create their own example of what the TCP/IP layer will be. You can use the previous slide as an example. You can look up ideas on the internet, just make sure you don’t copy one straight from it. After every group has made an example, each one will tell us about their example and how they think each part fits where it fits. (Note: This should take about 15 – 30 minutes in all, half the time for searching, and half the time for each group’s presentation.)
Transition:Alright, let’s what 2 videos
MP4. Videos
Alright, before we do an activity, let’s look at 2 videos that show us how the packets move through the network. They are a little silly, but they will give us a good idea of how it’s done. (Note: Play the 2 part video from the slides.)
And next let’s look at a video that will explain how to use the software Wireshark, which is a tool used to trace packets in a network. (Note: Play video about wireshark from website linked on PowerPoint.)
Transition: Alright, now that we’ve seen the videos, let’s do a step by step example to see how it works with software and packet tracing software.
MP5. Example
Example 1 (Note: For this activity, make sure there is a client and server that you can send packets to and from, and also that you can use wireshark to sniff. Will need a simple network setup for this.)
(Note: Use these sites for the filtering to see the packet sent to the server:
)
Alright, now let’s go through a simple packet trace simulation. (Note: For this example, show how a packet is sent from client to server, and then another example of how wireshark can sniff the packet as it’s going from client to server. Be sure to explain how to do it step by step.)
Transition: Ok, we’ve seen how a simple network works, and how wireshark works to see packets passed through the network, so now let’s try this in groups.
MP6. Group attack!
Activity 3 (Note: For this activity, make sure the students have a client and server program they can run to see how packets go from client to server)
For the first activity, go ahead and try out sending files from your computers to the server. Before you send the files, make a folder on the server for your group, and send your files to there. Then, after you have sent them, look at the server and see if the file is there. (Note: Wait 5-10 minutes for this)
Activity 4
For the second activity, have one or two of your group members use wireshark while two of your group members are sending data to the server and getting data from the server. The goal of the wireshark members is to get data from the packets, so the other two members should send data that the wireshark members don’t know about. After you have done that a couple of times, switch roles and do it again with the server client pair doing wireshark and the wireshark pair sending data to and from the server. (Note: This activity should take about 15-30 minutes.)
Transition:Ok, now that we’ve had some fun, let’s wrap up this class.
Conclusion
Summary: We started this section with each group designing their own networks. Then we went into a discussion about what we thought networks were, and why we needed them. Next we went into details about the basics of networks, some of the protocols, and what happens on networks. After that, we had an example showing how servers and clients send packets, and how you can sniff the packets. Finally, we broke up into groups and did some activities where we sent packets, sniffed the packets part of our group sent, and also tried to sniff packets other groups sent.
Remotivation:
Closure:Networking is a big part of cyber security. Just about everyone uses networks, and just about every company has need for people to both build the networks and keep the security of the networks as good as possible. Now that you are equipped with a little knowledge of how the bad guys can get information, you can better prepare for a future job where you will protect a company from an embarrassing situation (cough cough Sony cough cough).