I've been analyzing security costs for a multi-account AWS environment, specifically the ongoing operational expense of running Cisco Firepower NGFW in an AWS VPC versus relying solely on native AWS security groups and Network ACLs. The financial overhead is significant and often underestimated in TCO models.
A typical deployment uses a pair of Firepower Threat Defense (FTD) virtual appliances for HA across two Availability Zones. The core cost components are:
* **Software Subscription:** Cisco's Bring-Your-Own-License (BYOL) hourly rate for the FTD image. For a `c5.xlarge` instance type, this is approximately $0.45/hour per instance.
* **EC2 Instance:** The underlying compute cost for the `c5.xlarge`. On-Demand in us-east-1 is ~$0.17/hour.
* **Data Processing:** Firepower charges per GB inspected. At a modest 1 Gbps sustained throughput, this can be terabytes per day.
A simplified annual cost for two `c5.xlarge` FTD VMs (without data processing fees) looks like this:
```text
2 instances * ( ($0.45 + $0.17) / hour ) * 24 hours * 365 days = $10,857.60
```
This does not include the data processing fee, which can easily double this figure under load.
In contrast, AWS Security Groups and NACLs are provided at no additional cost beyond the standard data transfer charges. The cost of a native security model is essentially zero from a licensing perspective. The operational cost shifts to engineering time for managing rules and the potential risk of misconfiguration.
The critical question is whether the advanced, stateful inspection features of Firepower (IPS, malware detection, application control) justify this ~$11k+/year baseline. For many workloads, a combination of Security Groups, VPC flow logs, AWS Network Firewall (which is still cheaper than Firepower), and gateway load balancer endpoints for third-party virtual appliances can provide a more cost-effective and scalable security posture.
I'm interested in real-world numbers from teams who have done this analysis. What was your final cost per inspected GB, and did the enhanced security controls materially reduce other costs (like incident response) to offset the premium?
Right-size or die
I'm a senior FinOps analyst for a mid-market SaaS company with around 300 EC2 instances spread across 12 AWS accounts. We migrated from a hybrid Cisco ASA/FTD perimeter model to a fully native AWS security posture about 18 months ago and track the cost implications monthly.
1. **Annualized Base Cost Differential**
The FTD model's baseline compute + license cost starts near $11k, as you calculated. The native model using Security Groups and NACLs has a hard cost of $0. The operational cost shifts to the engineering time required to design and maintain the rule sets, which in my environment consumes about 5-8 hours of a senior engineer's time per month for auditing and updates. At a blended rate, that's roughly $15k-$24k annually, which can still be less than FTD when you factor in FTD's data processing fees.
2. **Throughput Cost at Scale**
Your missing data processing fee is the critical variable. In our pre-migration analysis, Firepower's per-GB inspected charge added ~40% to the total cost at an average of 850 Mbps. For a sustained 1 Gbps flow, you're inspecting about 10 TB daily. At Cisco's listed rate of $0.08/GB (varies by region), that's ~$800/day or ~$292,000 annually, which completely eclipses the base subscription. Native AWS security has no per-byte charge; its limitation is the instance-type-dependent network bandwidth cap.
3. **Operational and Integration Effort**
Deploying and managing FTD requires specialized network security skills distinct from cloud proficiency. In my last shop, maintaining HA pair failover configurations and troubleshooting Cisco-specific VPN bugs required a dedicated network engineer. Migrating to native security groups centralizes control with the cloud team using Terraform or CloudFormation, reducing context switching but requiring a solid IaC framework. The initial transition took us 3 months to refactor all application security group dependencies.
4. **Inspection Depth and Feature Gap**
Native security groups are stateful packet filters; they do not perform deep packet inspection, intrusion prevention (IPS), or malware detection. If your compliance framework mandates layer 7 inspection for specific workloads, native tools cannot fulfill that. FTD provides that depth. However, for many web and app tiers, we found AWS's combination of security groups, VPC flow logs (for audit), and AWS Network Firewall (for the few subnets needing L7) to be sufficient at about one-third the cost of a full FTD deployment.
I would recommend native security groups for the majority of use cases where the primary requirement is microsegmentation, basic stateful filtering, and compliance with least-privilege network access. If you have a regulatory or internal mandate for deep packet inspection and intrusion prevention on all east-west traffic, or if you are operating under a strict centralized firewall management model inherited from on-premises, then FTD may be necessary. To make a clean call, tell us your annual data throughput in terabytes and whether you have a hard requirement for IDS/IPS on internal traffic.
Yeah, that's a solid breakdown of the baseline hardware cost. I'm curious about the data processing fees though, you mentioned they could double it.
Is there a typical ratio people see, like cost per inspected GB? I've only ever used security groups, so seeing the raw numbers for a full NGFW is eye-opening.
Also, do those BYOL hourly rates ever drop with Reserved Instances, or is it purely subscription based?
The data processing fees can really catch you off guard. We ran a similar setup for a client's compliance requirements and saw the inspection costs spike during a marketing campaign when traffic volume jumped, even though the actual threat activity was low. It felt like paying a toll for every car on the road, regardless of whether any were speeding.
Your point about the TCO being underestimated is spot on. People often just compare the license and instance costs, but the variable fee based on throughput makes forecasting tough, especially for applications with unpredictable traffic patterns.