On the 15th March, 2023 Microsoft announced the general availability of Azure Firewall basic.
Azure Firewall is a cloud native network security service that provides threat protection for cloud workloads running in Azure. It is a stateful service offering both east/west and north/south protection along with high availability and scalability. Azure Firewall is available in 3 SKUs – Standard, Premium and now Basic. All 3 versions provide the following features:
- Built-in high availability
- Availability Zones
- Application FQDN filtering rules
- Network traffic filtering rules
- FQDN tags
- Service tags
- Threat intelligence
- Outbound SNAT support
- Inbound DNAT support
- Multiple public IP addresses
- Azure Monitor logging
- Certifications
And while Premium has additional features such as TLS inspection and IDPS, the Basic SKU has the following limitations:
- Supports Threat Intel alert mode only.
- Fixed scale unit to run the service on two virtual machine backend instances.
- DNS proxy is not available
- Recommended for environments with an estimated maximum throughput of 250 Mbps.
Where Azure Firewall Basic comes into its own is in cost to run. The Basic pricing model is designed to provide essential protection to SMB customers at an affordable price point for low volume workloads.
Approximate Costs
At the time of writing this article, the approximate retail costs for running Azure Firewall are:
| SKU | Cost |
| Basic | $0.592 (AU) per deployment hour or $432.16 (AU) per month |
| Standard | $1.871 (AU) per deployment hour or $1,365.83 (AU) per month |
| Premium | $2.619 (AU) per deployment hour or $1,911.87 (AU) per month |
As you can see, Azure Firewall Basic is considerably cheaper than the Standard or Premium SKUs just to turn on. But as mentioned previously, it is only for small workloads. The processing costs for data through Azure Firewall Basic are roughly 4 times more expensive.
If we look at processing 100GB in an hour the running costs would look like:
| SKU | Cost per GB | Processing cost | Total cost (inc run cost) |
| Basic | $0.098 (AU) | $9.80 (AU) | $10.39 (AU) |
| Standard | $0.024 (AU) | $2.40 (AU) | $4.27 (AU) |
| Premium | $0.024 (AU) | $2.40 (AU) | $5.02 (AU) |
Clearly, sustained high workloads are more expensive through the Basic SKU as opposed to the Standard or Premium SKUs. The basic SKU is cheaper only when customers are processing less than approximately 9,490GB per month, or 13GB per hour.
Recommendation
The new pricing model provides a much cheaper option for SMB customers to secure essential workloads at an affordable price where their data volumes are low.
This article is also published here.
