Network Security Group Rules Overview

Scope

In this lab, you will apply Network Security Group (NSG) rules to a subnet containing a virtual machine running nginx. You will see how a predefined rule that blocks inbound traffic prevents internet connections to that VM; how adding a rule with a smaller priority number allows public connections; how the statefulness of NSG-controlled connections affects the processing of inbound and outbound rules; and how reordering inbound rule priorities affects connectivity.

Suggested Pre Requisites

This lab will be entirely conducted in the Azure portal, via a Web browser.

Overview

In this lab, you will apply Network Security Group (NSG) rules to a subnet containing a virtual machine running nginx. You will see how a predefined rule that blocks inbound traffic prevents internet connections to that VM, how adding a rule with a smaller priority number allows public connections, how the statefulness of NSG-controlled connections affects the processing of inbound and outbound rules, and how reordering inbound rule priorities affects connectivity.

Scenarios

• Attempt to connect to a VM that does not allow Internet connectivity via TCP.


• Create a rule that allows connections to the VM on port 80, and see how its lower priority number allows you to connect to the machine.


• Attempt to block a response from the web server using an outbound rule, and see how the statefulness of the inbound rule prevents that outbound rule from blocking the response.


• Reorder the inbound rules, to see how doing so again prevents public connectivity to the VM.