Introduction to NSGs

Let me start by saying that NSGs are arguably one of the most critical components in the Azure network design and architecture. NSGs enable the overall flow and filtering of both inbound and outbound traffic within a virtual network, between subnets and VMs, internet traffic, and additional Azure services, such as storage.

Individual security rules can allow or deny inbound or outbound traffic to or from various Azure resources, and are grouped into NSGs that can then be assigned to the following:

• A single network interface, allowing filtered network traffic on a singular interface
• An entire subnet, allowing filtered traffic on all the network interfaces in the subnet
• Both the network interface and the subnet, allowing each NSG to be independently evaluated for the application of security rules

The security rules are based on the following properties:

• A Name value that is unique within the NSG
• The source/destination IP address...