Azure NSG vs VNet which is best for Network Security

Azure NSG vs VNet-This blog post delves into their functionalities, compares their features, and explores their respective use cases with a comprehensive comparison table.

Understanding Azure NSG and VNet

Azure Network Security Group (NSG)

An Azure Network Security Group acts as a virtual firewall for controlling inbound and outbound traffic to Azure resources, such as virtual machines (VMs) and Azure App Services. NSGs allow you to define rules that permit or deny traffic based on source and destination IP addresses, ports, and protocols.

Azure Virtual Network (VNet)

Azure Virtual Network provides a logically isolated network in the cloud, enabling you to securely connect Azure resources and extend on-premises networks to the cloud. VNets can be segmented into subnets to organize resources and control network traffic flow. Additionally, VNets support various connectivity options, including site-to-site VPN, Azure ExpressRoute, and Azure VPN Gateway.

Key Features and Use Cases

Azure Network Security Group (NSG)

  • Traffic Filtering: NSGs allow you to filter traffic by defining inbound and outbound security rules.
  • Application Security: Protect applications by restricting access based on IP addresses, ports, and protocols.
  • DDoS Protection: Mitigate distributed denial-of-service (DDoS) attacks with NSG rules that block malicious traffic.
  • Compliance: Ensure compliance with regulatory requirements by enforcing network access controls.
  • Use Cases: Ideal for securing VMs, Azure SQL databases, Azure Kubernetes Service (AKS) clusters, and other Azure resources.

Azure Virtual Network (VNet)

  • Network Isolation: VNets provide network isolation to prevent unauthorized access to resources.
  • Connectivity Options: Establish secure connections between on-premises networks and Azure resources using VPN or ExpressRoute.
  • Subnet Segmentation: Organize resources into subnets to enforce network segregation and implement granular access controls.
  • Scalability: Scale your network infrastructure to accommodate growing workloads and expanding deployments.
  • Use Cases: Suitable for hosting multi-tier applications, creating secure hybrid environments, and implementing network segmentation.

Comparison Table: Azure NSG vs VNet

Feature Azure Network Security Group (NSG) Azure Virtual Network (VNet)
Functionality Firewall for controlling traffic to and from Azure resources Logical network for connecting Azure resources
Traffic Control Filters traffic based on source and destination IP addresses, ports, and protocols Provides network isolation and segmentation
Use Cases Securing VMs, Azure App Services, and other Azure resources Hosting multi-tier applications, hybrid connectivity
Scalability Applies to individual resources or resource groups Supports network-wide configurations and scaling
Integration Integrates with Azure resources via association with VMs, subnets, or NICs Central component of Azure networking architecture
Connectivity Controls traffic within Azure and between Azure and on-premises networks Facilitates connectivity with on-premises networks
Management Configured through Azure Portal, PowerShell, Azure CLI, or ARM templates Configured through Azure Portal, PowerShell, or CLI
Security Provides layer 4 filtering for TCP/UDP traffic, stateful inspection Ensures network-level security through isolation
Scalability Scales horizontally to accommodate increasing numbers of resources Scales to support growing workloads and deployments
Monitoring Provides logging and monitoring capabilities for traffic flows Monitors network traffic, performance, and connectivity

Use Cases

Azure Network Security Group (NSG)

  1. Web Application Security: Restrict inbound traffic to web servers by allowing only HTTP (port 80) and HTTPS (port 443) traffic.
  2. Database Access Control: Secure Azure SQL databases by permitting traffic only from authorized IP addresses.
  3. Backend Service Protection: Protect backend services by blocking all incoming traffic except from specific Azure resources.

Azure Virtual Network (VNet)

  1. Hybrid Cloud Connectivity: Establish a site-to-site VPN connection between on-premises networks and Azure VNets for hybrid cloud scenarios.
  2. Multi-Tier Application Hosting: Deploy multi-tier applications with web, application, and database tiers within separate subnets for improved security and scalability.
  3. Regional Deployment: Deploy Azure resources across multiple Azure regions and connect them via VNets for redundancy and high availability.

Integrating Azure NSG and VNet

Azure NSGs and VNets complement each other to provide comprehensive network security and connectivity solutions. By integrating NSGs with VNets, you can enforce security policies at the network perimeter and within individual subnets, ensuring granular control over traffic flows.

Example Integration:

  1. Define NSG Rules: Create NSG rules to allow or deny traffic to specific Azure resources based on source IP addresses, ports, and protocols.
  2. Associate NSGs with Subnets: Associate NSGs with VNets and subnets to enforce security policies at the subnet level.
  3. Apply Network Security Policies: Implement network security policies that govern traffic between different tiers of an application, ensuring least privilege access.

External Resources

  1. Azure Network Security Group Documentation
  2. Azure Virtual Network Documentation

Frequently Asked Questions (FAQs)

Q1: Can I apply multiple NSGs to a single Azure resource?

  • A1: Yes, you can associate multiple NSGs with a single Azure resource, but keep in mind that the rules are cumulative, so ensure there are no conflicting rules.

Q2: How do NSGs differ from Azure Firewall?

  • A2: NSGs provide basic layer 4 filtering for traffic to and from Azure resources, whereas Azure Firewall is a fully stateful firewall as a service with application-level filtering capabilities.

Q3: Can I use VNets to connect multiple Azure subscriptions?

  • A3: Yes, Azure VNets can span across multiple Azure subscriptions and Azure Active Directory (Azure AD) tenants, allowing for centralized network management and connectivity.

Q4: What is the difference between a subnet and a VNet?

  • A4: A VNet is the overarching network infrastructure in Azure, while subnets are subdivisions of a VNet used to segment resources and control traffic flows within the VNet.

Q5: How does Azure VNet peering differ from VPN Gateway connectivity?

  • A5: VNet peering enables connectivity between VNets within the same region and offers lower latency and higher bandwidth compared to VPN Gateway connections, which establish secure connections over the internet or dedicated WAN links.


Azure Network Security Groups and Virtual Networks are essential components of Azure networking, offering robust security and connectivity features for cloud deployments. By understanding their functionalities, use cases, and integration strategies, you can design and implement resilient and secure network architectures in Azure.

Whether you’re securing Azure resources with NSGs or building scalable network infrastructures with VNets, Azure provides the tools and capabilities to meet your networking requirements and adapt to evolving business needs. Experiment with NSGs and VNets in your Azure environment to optimize network performance, enhance security posture, and drive digital innovation.