Anthropic-Cybersecurity-Skills/skills/analyzing-network-flow-data-with-netflow/SKILL.md

name, description, domain, subdomain, tags, version, author, license

name	description	domain	subdomain	tags	version	author	license
analyzing-network-flow-data-with-netflow	Parse NetFlow v9 and IPFIX records to detect volumetric anomalies, port scanning, data exfiltration, and C2 beaconing patterns. Uses the Python netflow library to decode flow records, builds traffic baselines, and applies statistical analysis to identify flows with abnormal byte counts, connection durations, and periodic timing patterns.	cybersecurity	network-security	analyzing network flow data	1.0	mahipal	MIT

Instructions

1. Install dependencies: pip install netflow
2. Collect NetFlow/IPFIX data from routers or use the built-in collector: python -m netflow.collector -p 9995
3. Parse captured flow data using netflow.parse_packet().
4. Analyze flows for:
   • Port scanning: single source to many destinations on same port
   • Data exfiltration: high byte-count outbound flows to unusual destinations
   • C2 beaconing: periodic connections with consistent intervals
   • Volumetric anomalies: traffic spikes beyond baseline thresholds
5. Generate a prioritized findings report.

python scripts/agent.py --flow-file captured_flows.json --output netflow_report.json

Examples

Parse NetFlow v9 Packet

import netflow
data, _ = netflow.parse_packet(raw_bytes, templates={})
for flow in data.flows:
    print(flow.IPV4_SRC_ADDR, flow.IPV4_DST_ADDR, flow.IN_BYTES)