When a mysterious spike threatened to break the bank, a cash-strapped operations team built an enterprise-grade NetFlow collector using only open-source software and a refurbished server. Act 1: The Mystery of the Vanishing Bandwidth The trouble began on a quiet Tuesday. Our small but growing SaaS company, "LucidCloud," had just migrated its core infrastructure to a new colocation facility. The CEO was ecstatic about the new 10GbE uplink. The CFO, however, was not.
"Our bandwidth bill has tripled," she said, sliding a printout across the table. "Find out who’s downloading the Library of Congress." free netflow collector
We had the usual tools: SNMP (Simple Network Management Protocol) gave us graphs of how much traffic—fat, wiggly lines showing utilization at 95%. But it couldn't tell us who or what . Was it a customer's misconfigured backup? A compromised VM mining crypto? Or just someone streaming 4K cat videos to the breakroom TV? When a mysterious spike threatened to break the
The problem: Commercial collectors (SolarWinds, Scrutinizer, etc.) cost more than our monthly AWS bill. "There's no budget," the CTO declared. "Get creative." We decided to build our own. The plan was audacious: a completely free, scalable NetFlow collector on a dusty Dell PowerEdge R720xd we found in the storage closet. The CEO was ecstatic about the new 10GbE uplink
Jake woke us up. "Uh, we're getting 300,000 flows per second." The collector was pinned. The Python script fell over. We realized our sampling rate was wrong. We tweaked the router from sampling-rate 1000 to sampling-rate 5000 (1:5000 packets). Suddenly, 6,000 flows/sec. Manageable.
We needed visibility. We needed flows. We needed a NetFlow collector.