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We sell Flowtriq, a commercial DDoS detection product. We benefit when teams move from open-source to commercial solutions. The cost estimates below are based on typical infrastructure pricing and common operational patterns for self-hosted detection deployments.

The open source DDoS detection landscape

The most widely deployed open-source DDoS detection tool is FastNetMon Community Edition. It provides NetFlow/sFlow-based traffic monitoring with configurable PPS, BPS, and flow thresholds, plus callback scripts for automated response (typically RTBH). Other options include custom setups built on ntopng, Zeek, or GoFlow2 with Grafana dashboards.

These tools work. They provide real value. The question is not whether they are useful, but whether the total cost of operating them in production is lower than the alternatives.

Cost layer 1: Infrastructure

Every self-hosted detection tool needs a server. FastNetMon's documentation specifies minimum requirements of 16 GB RAM, 8 CPU cores with SSE 4.2 support, and 150+ GB SSD for their commercial product. Community Edition can run on less, but production deployments processing real NetFlow data from busy routers need adequate hardware.

Typical infrastructure costs:

  • Dedicated server: $60-150/month depending on provider and specs
  • Bandwidth for flow data: Usually negligible (sampled flows are small), but worth accounting for
  • Monitoring of the monitoring: You need to know if your detection server goes down. That is another monitoring integration to maintain.

Annual infrastructure cost: $720-1,800/year

Cost layer 2: Setup and integration

Getting a detection tool from "installed" to "production-ready" involves significant engineering work:

  • Initial setup: Installing, configuring flow collection, tuning thresholds for your traffic patterns. Estimate: 8-16 hours.
  • Alerting integration: Building webhook handlers, PagerDuty/Slack integrations, email notifications. Open-source tools provide callback scripts; you build the rest. Estimate: 4-8 hours.
  • Dashboard: No built-in web interface. Most operators build Grafana panels with InfluxDB or Prometheus backends. This requires setting up the time-series database, creating dashboards, and maintaining them. Estimate: 8-20 hours.
  • SIEM integration: Shipping detection events to your security platform. Usually involves log parsing and format conversion. Estimate: 4-8 hours.
  • Mitigation automation: Callback scripts for RTBH or FlowSpec. Writing, testing, and validating BGP announcement scripts requires careful work since mistakes can affect routing. Estimate: 8-16 hours.

Total setup estimate: 32-68 hours. At $75-150/hour for a network engineer (depending on market and seniority), that is $2,400-10,200 in setup labor.

Cost layer 3: Ongoing maintenance

Self-hosted detection does not run itself after setup:

  • Updates and patching: OS and detection software updates, dependency management, regression testing after updates. Estimate: 2-4 hours/month.
  • Threshold tuning: Traffic patterns change. Seasonal shifts, new customers, network growth all require threshold adjustments. Without dynamic baselining, this is manual work. Estimate: 1-2 hours/month.
  • Dashboard maintenance: Grafana dashboards break when data sources change, metrics are renamed, or the detection tool updates its output format. Estimate: 1-2 hours/month.
  • Integration fixes: Webhook endpoints change, alerting services update their APIs, SIEM ingest formats evolve. Each break requires debugging. Estimate: 1-2 hours/month.

Monthly maintenance estimate: 5-10 hours/month, or 60-120 hours/year. At $75-150/hour: $4,500-18,000/year in maintenance labor.

Cost layer 4: Incident response without support

When your detection tool behaves unexpectedly during an attack, and eventually it will, you troubleshoot alone. No vendor to call. Community forums and GitHub issues are your support channels, and they do not operate on incident timelines.

The cost is not just the engineer time spent troubleshooting. It is the extended incident duration, the customer impact during the delay, and the SLA credits or reputation damage from a slower response.

Full TCO model: Year 1

Open source DDoS detection (conservative estimate)

Software license$0
Server infrastructure (12 months)$1,200
Initial setup (40 hours @ $100/hr)$4,000
Ongoing maintenance (80 hours @ $100/hr)$8,000
Vendor support$0 (none available)
Year 1 TCO~$13,200

Flowtriq (10 nodes, unlimited users)

Detection + mitigation + dashboard (annual)$959
Server infrastructure$0 (SaaS)
Setup time (agent install, ~1 hour)$100
Ongoing maintenance$0 (managed)
Vendor supportUnlimited, included
Year 1 TCO~$1,059

Note: Engineer time estimates vary significantly based on experience, existing infrastructure, and complexity of the network. Some operators with deep experience can set up and maintain open-source detection in half the estimated time. Others, especially those doing it for the first time, will spend more. The key insight is that engineer time is not free, even if the software is.

When open source is the right choice

Despite the TCO, open source DDoS detection is the right choice in specific situations:

  • Learning and development: Building detection from scratch teaches you how DDoS detection works at a level that commercial tools abstract away.
  • Extreme customization: If your detection requirements are highly specific and no commercial tool fits, building on open-source gives you full control.
  • Budget constraints with available engineer time: If you have engineer time but no software budget, the TCO equation shifts. The labor is already paid for.
  • Air-gapped or restricted environments: Environments where SaaS solutions are not permitted for compliance or security reasons.

Skip the build. Start detecting in 60 seconds.

Flowtriq replaces the server, the Grafana dashboards, the webhook scripts, and the threshold tuning with a single agent install. $9.99/node/month. 14-day free trial.

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Frequently asked questions

How much does open source DDoS detection actually cost?
While the software is free, production costs include dedicated server infrastructure ($60-150/month), engineer time for setup (32-68 hours) and maintenance (5-10 hours/month), custom integration development for dashboards and alerting, and the operational impact of no vendor support during incidents. Realistic Year 1 TCO is $5,000-15,000+ depending on infrastructure and labor costs.
Should I use open source or commercial DDoS detection?
Open source is right when you have dedicated engineer time, your needs are limited to basic threshold detection and RTBH, and your team has deep experience. Commercial makes sense when you need attack classification, forensics, a dashboard, an API, and vendor support without building those capabilities yourself. The decision depends on whether you have more budget or more engineer time.

The bottom line

"Free" is the license cost. It is not the total cost of ownership. Open-source DDoS detection requires infrastructure, engineering time, and ongoing maintenance that add up to a real number. For some organizations, that number is lower than commercial alternatives because the engineer time would be spent anyway. For others, especially small teams where every hour of engineer time competes with other priorities, the total cost of "free" exceeds the cost of a commercial solution that includes everything out of the box.