Reference no: EM133085862

Lab Sheet - The Application Layer

Objectives
• Investigate different applications on application layer
• Explore how to use VirtualBox on a USB stick to save and exchange files
• Create two Linux Lite instances communicating on the same host machine

Introduction
User applications communicate through the facilities provided by computer networks. This week's lab focuses on some important application layer protocols and programs that use these protocols to facilitate data transfers between client/user and server applications.

Task 1: Categories of User Applications
Use the Internet and determine the names of at least two user applications that fit into the following categories of network applications.
• Email
• Social Media
• Audio Streaming
• Video Streaming
• File Transfer
• VoIP
• Video Conferencing
• Web Searching
• Your Choice
• Your Choice

Task 2: Common Web Server Programs
• In client server computing, web clients (user applications) include FireFox, Chrome, Safari, Internet Explorer, etc. Describe the names of most popular web server platforms used on the following platforms.
o Linux
o Windows
• What is the current market share of each platform?

Task 3: Common Email Server Programs
• What platforms does exchange server run on?
• Name three mail server programs that run on Linux and Windows but not on Mac.

Investigate Application Layer Protocols (1 mark)
Some application layer protocols that are discussed in week 3 lecture slides are
• HTTP (Hypertext Transfer Protocol)
• FTP (File Transfer Protocol)
• BitTorrent
• NTP (Network Time Protocol)

The Wikipedia application layer page lists many protocols. Choose two protocols and briefly describe their use. Your description must be written with Linux Lite LibreOffice writer and must contain enough details so you can describe its operation to your lab tutor (online students should include a screenshot of their 1-2 paragraph(s) description in their first lab tasks report).
Working with VirtualBox
VirtualBox allows a USB stick to be concurrently accessed from Linux Lite Virtual Machine (VM) and Windows host operating system. It gives us the ability to save files created on Linux Lite to a USB device. It also enables us to use a USB stick to transfer files between Linux and Windows. To transfer the files, the USB stick must be inserted on the Windows machine prior to running VirtualBox. The drive letter setting in line 15 of vb.bat file must be correct for successfully sharing the USB stick as described above. The USB stick can be accessed from directory /mnt/vbox/ on your Linux Lite VM.

Task 4: Accessing a USB Stick from a Virtual Machine
1. Run C:\VBoxImages\RefreshImages.bat to reset the VMs to their initialization state.
2. Insert a USB stick into Windows host machine.
3. Run C:\VBoxImages\vb.bat.
4. Start Linux Lite.
5. Run text editor application from the Menu
o Menu -> Accessories -> Text Editor (This is the Linux equivalent to Notepad).
o Write a few lines of text in the editor.
o select File -> Save As -> File System -> mnt -> vbox.
o Give file name and use the extension .txt for Windows compatibility.
o The file will save on the USB stick.
6. Minimize Linux Lite.
o Open Windows explorer on your Windows host machine.
o Copy the file created in step 5 and paste to your Windows desktop.
7. In this exercise, you have been able to save files created in Linux to a USB stick and share the files with the underlying Windows operating system.
8. You can also try copying files from Windows to Linux Lite.

Task 5: Taking Screenshots in Linux
The Linux Lite Accessories menu has a program for creating screenshots.
With this program, you can take a screenshot of the entire screen or just the active window. After the screenshot is taken, you will be prompted to save the screenshot. You can save the file to your Linux Lite home directory (as shown below), or to the USB stick at /mnt/vbox/

Task 6: Cloning of a Virtual Machine
Sometimes, you may want more than one instance of Linux Lite running at the same time, e.g., when networking between two Linux Lite machines that are running on the same host operating system. To successfully get two Linux Lite instances with separate identities (different IP addresses) on one host computer, it is important to select the option "Reinitialize the MAC address of all network cards" as show below.

The reason for this step is that when a Linux Lite VM boots, it requests for IP settings from a local DHCP server. Most home routers provide DHCP as a part of their basic functionality. If MAC addresses of two Linux Lite machines are the same, then both machines will receive the same IP address settings and will not be able to exchange data over the network. By Reinitializing all MAC addresses, the Linux Lite instances acquire different IP addresses from the DHCP server.
• To create a clone of a Linux Lite instance, close all running VMs.
• Click on the Linux Lite instance in the left-hand pane of VirtualBox interface.
• Click Machine -> Clone (as shown in the image).

• Click "Expert Mode" -> select "Linked Clone" -> Reinitialize the MAC address of all network cards (as shown in the image).

You are now ready to run two instances of Linux Lite concurrently on the same host machine. From a networking perspective, this is identical to having two different sets of hardware (computers) each running a Linux Lite. Now you can do various networking tasks between Linux Lite instances and

Windows host operating system. If required, you can also run up Windows 8.1 virtual machine and have all four operating systems networking.

Task 7: Observing Network Settings on Linux Lite
• Run original Linux Lite VM.
• Open a Terminal session and type command ifconfig. It will display network settings of current Linux Lite instance. The output should resemble the screenshot below. in the third line, you can see the IP address (in this case, it is 192.168.0.23)

Task 8: Running Linked Clone
• Start Linux Lite linked clone image.
• Open the terminal window and determine the IP address of the clone. It should be different from the one seen in the previous screenshot. (note the last 2 digits)

Task 9: Confirming Connectivity Between Machines Using ping Command
ping command is used to check the network connectivity between two machines on a network. For example, in the below screenshot, we are working on a linked clone with an IP address 192.168.0.24. To see if we have the connectivity with the other machine, we must ping 192.168.0.23. (See the output of ping command at the bottom of the terminal screenshot). The output of ping command shows that we have the connectivity with a machine with an IP address 192.168.0.23 and that it takes a little for destination machine to reply.

ping Command
Demonstrate a cloned Linux Lite instance pinging the base Linux Lite image. (Online students should include a clear screenshot in their first lab report)

Attachment:- The Application Layer.rar