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Practical Worksheet 5

Version: 1.1 Date: 28/08/2018 Author: David Glance

Learning Objectives

  1. Networking and NAT
  2. Setting up an Application Load Balancer

Technologies Covered

Ubuntu AWS AWS ELB Networking NAT Python/Boto scripts VirtualBox

Note: Do this from your VirtualBox VM – if you do it from any other platform (Windows, Mac – you will need to resolve any potential issues yourself)

Background

The aim of this lab is to write a program that will:

[1] Understand how to configure different network arrangements to gain and control access to computers and other networked resources [2] Understand IP addressing and CIDR and the meaning of TCP and UDP ports

Networking

[Step 1] Configure inbound IP on VirtualBox VM

This can be done in a number of ways, but we are going to use NAT port mapping. When a VM is created in VirtualBox, it defaults to creating a single NAT interface

[1] The VM does not have to be stopped for this but it isn’t a bad idea to make changes when it is stopped. [2] In the VirtualBox Manager, select the VM you want to configure, then click Settings (Golden Gear Cog) and Network. Adapter 1 should be configured as NAT. Click on Advanced and then Port Forwarding. Set up 2 rules: [a] Use the localhost host IP 127.0.0.1 and host port 2222 and map that to Guest Port 22 [b] Add a similar rule mapping Host Port 8080 to Guest Port 80

[3] Testing! You can test the NAT’d ports by running your docker app and seeing if you can access it from your computer – the url will be http://127.0.0.1:8080 Enable ssh to the VM by installing sshd as follows:

sudo apt install tasksel
sudo tasksel install openssh-server

start the ssh service by:

sudo service ssh start

you can stop it using:

 sudo service ssh stop

To ssh to the VM, open a terminal on your PC (or use Putty) and ssh as

ssh -p 2222 <usermame>@127.0.0.1

You should be prompted for your password

[Step 2] Setting up an Application Load Balancer

The aim of this part of the lab is to create an application load balancer and load balance requests to 2 EC2 instances. As there is a restriction of only 20 load balancers per region, we are going to relax the requirement to create instances and the ELB in the ap-southeast-2 region.

Before running the application to create a load balancer and instances, check how many are running in a particular region. Select a region that has capacity.

Remember Delete the load balancer immediately after completing the lab.

USE YOUR STUDENT NUMBER TO IDENTIFY ALL RESOURCES

Objective: Write an application to create 2 EC2 instances in two availability zones, create an application load balancer and load balance HTTP requests to the 2 instances.

You will need to do some manual intervention to get Apache 2 installed and the index.html file edited. Do this after you have created the instances and ALB. In a future lab you will learn how this could be done through a program as well.

[1] Write a Boto3 application to create 2 EC2 instances in two different availability zones of a specific region. Name the instances _zone

Note: You will need to use v2 of the ELB interface:

client = boto3.client('elbv2')

[2] Create the Application Load Balancer.

The steps involved in this are:

[a] Create the load balancer and specify the two region subnets and a security group

[b] Create a target group using the same VPC that you used to create the instances - note the ARN that is output

[c] Register targets in the target group

[d] Create a listener with a default rule Protocol: HTTP and Port 80 forwarding on to the target group

Try and access the EC2 instance using the public IP address of the load balancer in a browser. The load balancer will not be working at this point because Apache 2 is not installed. Check this and then:

On each instance, install apache2

sudo apt install apache2

Edit the /var/www/html/index.html file to report the instance name

Now Verify that the load balancer is working. You should be able to access both of the EC2 instances by refreshing the page.

IMPORTANT When finished. Delete the Load balancer, target group, listener and EC2 instances.

Lab Assessment:

This semester all labs will be assessed as "Lab notes". You should follow all steps in each lab and include your own comments. In addition, include screenshots showing the output for every commandline instruction that you execute in the terminal and any other relevant screenshots that demonstrate you followed the steps from the corresponding lab. Please also include any linux or python script that you create and the corresponding output you get when executed. Please submit a single PDF file. The formatting is up to you but a well organised structure of your notes is appreciated.