Configure IP Routing with Linux on Azure

This Configure IP Routing with Linux on Azure IT Pro Challenge lab helps learners to understand how to configure IP routing for Linux Virtual Machines (VMs) that are deployed to an Azure cloud where the inter-subnet traffic is sent through a Network Virtual Appliance (NVA). Additionally, this lab demonstrates Azure route tables and their purpose and how/why to create a secondary IP address. Understanding IP routing is useful to those interested in a career as a Linux Administrator.

Overview

For the purposes of this hands-on lab, your organization uses Linux VMs in Azure. As the system administrator, you are tasked to use Azure and configure IP routing to control outbound traffic flow, where a Linux VM examines the traffic first before continuing to the Internet. You will also create a secondary IP address to a Linux VM, create an Azure route table directing specific IP traffic, and verify that the traffic is being routed through the Linux VM.

In the beginning of the lab, you are provided with 2 Ubuntu Linux VMs.

During the lab, you will need to use the PuTTY tool in order to test the IP routing that you configure. If you don’t have PuTTY installed, download it and install it on your local machine using the default installation options.

Add a second IP address to a Linux virtual machine

The first step of this virtual lab shows learners how to add a second IP address to a Linux virtual machine and explain the reason for a second IP address.

Simply put, when you set up a server, it has one IP address - the main IP address, which is linked to the server hostname. You should never host an application on the server main IP address, so that’s why it’s necessary to create a second IP address.

Create an Azure route table resource

In this section of the lab, learners will gain familiarity with creating a route table resource. This is necessary to manage traffic between virtual networks, traffic to the Internet, and more. When you create a route table resource, you’re creating network routes, and there can be more than one type of route. Generally speaking, user-defined routes take precedence over default system routes.

Configure an Azure route table route

One of the things that Azure does is route traffic between different networks. If you want to make any changes to the default routing, you need to create a route table (also known as User Defined Routing (UDR)).

NOTE: Azure allows you to create a maximum of 200 user-defined route tables.

Summary Conclusion

By taking this virtual lab, you will learn how to do the following:

• Add a secondary IP address to a network interface in the Linux operating system
• Create an Azure route table resource
• Add a route to an Azure route table
• Verify that the Azure route table route is in effect

You will also understand why it’s important to use a secondary IP address for applications, how there is more than one type of route, and how those routes are prioritized by the network.

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