Understanding NSG and Azure Firewall
When RSI sets up a virtual network in Microsoft Azure, security stays at the center of the design. Each client environment uses layered protection to reduce risk and control access. Two core tools support this approach: Network Security Groups and Azure Firewall. Each tool serves a different purpose, and together they create a strong security foundation.
What Is a Network Security Group (NSG)?
Network Security Groups act as the first line of defense inside an Azure virtual network. An NSG uses simple allow and deny rules to control traffic between network resources. These rules apply at the subnet or network interface level and help define how systems communicate.
A common example allows a virtual machine to send traffic out to the internet while blocking all inbound traffic. This setup limits exposure and reduces attack paths. NSGs do not add hardware or virtual appliances to the network. Instead, they work at OSI layers three and four, which keeps protection broad and efficient.
Administrators can also block specific ports with NSG rules. For example, an NSG can deny Remote Desktop Protocol access from the public internet. Internal users still connect to virtual machines through approved paths. This method protects systems while keeping daily operations smooth.
Below is an example of how NSG’s are used to protect access to the virtual network from the internet and allow RDP to an individual Azure VM through Bastion.
How Azure Firewall Adds Advanced Protection
Azure Firewall provides deeper control and visibility than an NSG alone. Microsoft fully manages this service, which reduces maintenance and improves reliability. Azure Firewall works alongside NSGs rather than replacing them.
This firewall operates across OSI layers three through seven. That coverage allows it to inspect traffic with more detail. Teams can allow or block traffic by IP address, website name, or geographic region. The firewall can also identify and respond to threats such as distributed denial of service activity.
Azure Firewall supports features like FQDN tags, source and destination filtering, and threat intelligence feeds. These tools help block known malicious traffic before it reaches internal systems. Clients may see a small cost increase, but the added security and support deliver clear value.
NSG vs Azure Firewall: Why RSI Uses Both
Network Security Groups filter traffic at a basic network level. Azure Firewall focuses on detailed inspection and intelligent control. Each tool fills a gap the other cannot cover alone.
RSI recommends using both solutions together for the strongest protection. NSGs handle baseline access rules, while Azure Firewall manages advanced threats and fine tuning. Experienced RSI administrators design and maintain these environments to align with each client’s needs.
Nothing matches the strength of combining Network Security Groups with Azure Firewall. This layered approach supports secure growth and long term stability in Azure.
Key Takeaways
- Network Security Groups (NSGs) control traffic in Azure networks using allow and deny rules, providing a first line of defense.
- NSGs limit exposure by allowing outbound traffic while restricting inbound access, enhancing security without adding hardware.
- Azure Firewall offers deeper security by inspecting traffic across OSI layers three to seven, providing advanced threat protection.
- Together, NSGs and Azure Firewall deliver a comprehensive security strategy, with NSGs managing basic rules and Azure Firewall handling complex threats.
- RSI advises using both NSGs and Azure Firewall for optimal protection and long-term stability in client environments.