analyzing-network-flow-data-with-netflow

analyzing-network-flow-data-with-netflow is a skill for Claude Code from mukul975/Anthropic-Cybersecurity-Skills. It costs 76 tokens per session (517 once invoked), scanned A, original, Apache-2.0.

A guide to reading NetFlow v9 and IPFIX records, which summarize network connections, with Python tools. It looks for unusual traffic patterns linked to attacks.

In plain words
What is it for?
Use it to collect and decode flow records, create normal-traffic baselines, and identify suspicious connections. It also helps produce a prioritized findings report.
Why use it?
It helps turn large amounts of connection data into findings that are easier to investigate. This can reveal scanning, data theft, hidden malware communication, and unusual traffic spikes.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the cybersecurity-skills plugin — 56 skills shipped together

Good fit Use it to collect and decode flow records, create normal-traffic baselines, and identify suspicious connections. It also helps produce a prioritized findings report.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mukul975/anthropic-cybersecurity-skills/analyzing-network-flow-data-with-netflow
About the project

Anthropic Cybersecurity Skills is a library of structured cybersecurity procedures for AI agents, covering security domains and mappings to established security frameworks. It is for authorized security analysis, penetration testing, incident response, research, defense, and education across compatible AI platforms. The catalogue entries package parts of this library as agent skills, instructions, or a plugin.

mukul975/Anthropic-Cybersecurity-Skills · 32,631 stars · on GitHub · mahipal.engineer

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-network-flow-data-with-netflow
Clone the repo
git clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills

Made for: Claude Code.

Or install cybersecurity-skills, the plugin that ships this one along with the rest of its 56 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for analyzing-network-flow-data-with-netflow

README.md
[![agentmods](https://agentmods.dev/badge/skills/mukul975/anthropic-cybersecurity-skills/analyzing-network-flow-data-with-netflow/github.svg)](https://agentmods.dev/skills/mukul975/anthropic-cybersecurity-skills/analyzing-network-flow-data-with-netflow)
Your own site
<a href="https://agentmods.dev/skills/mukul975/anthropic-cybersecurity-skills/analyzing-network-flow-data-with-netflow"><img src="https://agentmods.dev/badge/skills/mukul975/anthropic-cybersecurity-skills/analyzing-network-flow-data-with-netflow/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Your own site · 80×15
<a href="https://agentmods.dev/skills/mukul975/anthropic-cybersecurity-skills/analyzing-network-flow-data-with-netflow"><img src="https://agentmods.dev/badge/skills/mukul975/anthropic-cybersecurity-skills/analyzing-network-flow-data-with-netflow.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 76 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 517 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 6 Apr 2026
  • Snyk pass 6 Apr 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00076 $0.00517
Opus 5 $0.00038 $0.00259
Sonnet 5 $0.00015 $0.00103
Haiku 4.5 $0.00008 $0.00052

Measured 12d ago against content hash 7b6478574765, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

analyzing-network-flow-data-with-netflow scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/agent.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

5 near-identical copies found in the catalogue:

skills/analyzing-network-flow-data-with-netflow/SKILL.md · 73 lines

What it actually says

Analyzing Network Flow Data with Netflow

When to Use

  • When investigating security incidents that require analyzing network flow data with netflow
  • When building detection rules or threat hunting queries for this domain
  • When SOC analysts need structured procedures for this analysis type
  • When validating security monitoring coverage for related attack techniques

Prerequisites

  • Familiarity with network security concepts and tools
  • Access to a test or lab environment for safe execution
  • Python 3.8+ with required dependencies installed
  • Appropriate authorization for any testing activities

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)
Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 73 lines · 76 tokens per session scan A 7b6478574765

Subscribe to this mod's changes

analyzing-network-flow-data-with-netflow is a skill published in the GitHub repository mukul975/Anthropic-Cybersecurity-Skills (32,631 stars, last pushed 12d ago), licensed Apache-2.0. It adds 76 tokens to every session and 517 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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