Network Security Groups (NSGs) are fundamental security controls in Azure Virtual Networks. They act as virtual firewalls, allowing you to define rules to control network traffic.
- **Security Rules:** Define policies that control network traffic based on criteria like IP address, port, or protocol. - **Ingress/Egress Rules:** Control incoming and outgoing traffic. - **Resource Groups:** Associate NSGs with specific resources.
A typical NSG might restrict all inbound traffic to an application server to only allow connections from specific IP addresses.