DNS

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Overview

In this week's lab, we will acquire a domain name from your provider of choice, link it with the public IP address of your cloud machine, and then obtain a TLS certificate for free through Let's Encrypt.

A major objective of this exercise is to develop familiarity with the components that make up an "Internet Presence". A further goal of this unit is to empower students to build within the Internet rather than merely use it. You will only fully realise the objectives of this lab if you have total administrative control over your virtual machines and your domain name. At this point in the semester, we strongly recommend that students have their own account with a provider of their choosing. Some common choices are Amazon EC2, Microsoft Azure and Digital Ocean. Remember that another theme of this unit is that we want to show you approaches to solving problems, but we want to avoid heavily teaching any one tool where possible. This leaves you with the agency and option to choose the provider or tool that is best suited to you.

Domain Names & DNS

WARNING - Some cloud service providers won't let you use a country-code top-level domain (ccTLD) that is from an OFAC-sanctioned country. OFAC is a United States government department that is responsible for sanctions against other countries and are based on United Nations mandated sanctions in addition to US national security reasons and foreign policy. Current OFAC-sanctioned countries: https://worldpopulationreview.com/country-rankings/ofac-countries DigitalOcean - DNS QuickStart & How-Tos: https://docs.digitalocean.com/products/networking/dns/getting-started/quickstart/

Ensure you have access to a Cloud-based virtual machine

Launch an Ubuntu machine in the Amazon EC2 cloud. Ensure that you open SSH, port 22, HTTP, port 80 and HTTPS, 443, in the firewall. If you are unsure the lab Amazon EC2 Web Services or the videos in LMS that step you through Digital Ocean and Microsoft Azure.

The configuration of the virtual machine is not the focus of this lab. We recommend that you keep it simple so that we can move past this "revision element" and on to the substance of the lab. If you lack confidence in setting up a virtual machine, then redo the existing Amazon EC2 Web Services lab and commit some serious time to build your confidence.

If you are completing this lab at home or on your own, follow the steps for last weeks lab. Once your cloud-based virtual machine is configured and running in Amazon EC2 you should ssh into the server and install the Apache webserver as follows: 

sudo apt install apache2
  • Record the Public IP Address of your virtual machine in Amazon EC2: _________________________________________________

Open a browser and verify that your web server is running at that address. You should see the Apache welcome page. Do not continue with this lab until you have reached this step.

Obtaining and linking a domain name

Obtain a domain name from a Domain Name Registrar such as AWS Route 53, Namecheap, CloudFlare, Godaddy). Avoid leaving your credit card details or auto-renew on your domain name if you do not plan to use this domain name after this unit. With some providers, this is not possible. If this is the case remember to terminate your account at the end of the semester. Paying with Paypal might be an option.

After you have purchased your domain name, you want to link your domain name to your cloud machine. The most straightforward strategy from here is to create an A record that points to the Public Internet-facing IP address of your cloud-based machine. After these changes have been made, sometimes it will take a few hours for the DNS changes to propagate throughout the Internet. You should not proceed until you can verify that the domain name entered in a web browser URL goes to your website.


Launch an Ubuntu Machine in EC2

Launch an Ubuntu machine in the Amazon EC2 cloud. Ensure that you open SSH, port 22, and HTTP, port 80, in the firewall.

The configuration of the virtual machine is not the focus of this lab. We recommend that you keep it simple so that we can move past this "revision element" and on to the substance of the lab. If if you are lacking confidence in setting up a virtual machine, make sure you are using a Linux desktop and seek the assistance of the tutor.

If you are completing this lab at home or on your own, follow the steps for last weeks lab. Once your cloud-based virtual machine is configured and running in Amazon EC2 you should ssh into the server and install the Apache webserver as follows: 

sudo apt install apache2
  • Record the Public IP Address of your virtual machine in Amazon EC2: _________________________________________________

Open a browser and verify that your web server is running at that address. You should see the Apache welcome page.

Acquire a Domain Name

For this lab you will need to aquire a domain name:

  • Give consideration as to whether this is likely to be something that you intend to maintain in the longer term.
    • Do you want to pay to have your address details concealed?
    • Which TLD?
    • Should you pay for multiple years?
  • If you plan to use this just for this unit, you should minimise your cost.
    • Shouldn't be necessary to pay more than $2.
    • Many students have made use of a free name from http://www.freenom.com
    • Avoid leaving your credit card details or auto-renew on your domain name. With some providers, this is not possible. If this is the case remember to terminate your account at the end of the semester.
    • Paying with Paypal might be an option.

Whatever method you choose, you will need to sign up for a DNS entry before proceeding.

Configuring the DNS

  • You should already be logged into to Amazon AWS
  • Under Services, you should find and select the "Route 53" service (Amazon DNS).
  • Create a "Hosted Zone" found within DNS Management. Use the domain name that matches the domain name you just purchased.
  • Check the selection box next to your newly created Hosted Zone. On the right had side you will see instructions as to what configuration you need to apply within the management screen of your domain registry account (where you bought the domain name).
  • Apply the "Delegation Set" (4 domain names) present in Route 53 into the Name Server configuration fields with your domain registry account. The exact process differs between domain registries but they usually make it very obvious as to what needs to be done.
  • In Route 53, select your domain name check box and then click "Go to Record Sets".
  • Click on "Create Record Set".
  • Create an Authoritative entry (A record) for your domain name with the IP address you recorded earlier.

Permanent IP address

The IP address assigned to your virtual machine is temporary. When you restart the instance your IP address may change and consequently, your DNS entry will no longer point to your server's address. The solution is to assign a permanent address (known as an "elastic" address in Amazon AWS terms). This is optional for this lab but will be necessary for a production server and your assignment.
Steps:

  1. In the EC2 AWS console click on "Elastic IPs" on the left side of the window.
  2. Click "Allocate new address" and then "Allocate".
  3. Click the select box next to the IP address you just created.
  4. Use the "Actions" button to associate the address wor if using AWS, you can use AWS Route 53)ith your instance.

Your IP address will now be permanent and this is the IP address that your Domain Name should point to. You should update the existing A record to point to this new IP address.

Note: An IP address is free while a machine is running. However, you are charged a small monthly fee for reserving an IP address that is not in use. Please be sure to register for your $100 AWS credit to absorb these small charges.

Testing

Can you now browse to the web site? Can enter your domain name into a browser and reach your page? If not, troubleshoot.

  • Is the domain resolving correctly? (ping, nslookup) - Note: ping will not be successful unless a rule for ICMP has been added to the Security Group for your AWS Instance.

Experimenting

  • Who issued the certificates for murdoch.edu.au and for csn.murdoch.edu.au? Don't assume they are the same group. Click the lock sign next to the URL to find out.
  • Can you create an A record that points to another students server?
  • What happens if you create two A records with the same host name but different IP addresses?
    • Point the host-name at your web server and a public site. Which one is resolved?
    • Shutdown your server.
      • Does the DNS eventually failover to the second IP address?
      • How could this be used?
      • Why does it take so long?
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