Skill15.5k repo starsupdated 11d ago

analyzing-network-packets-with-scapy

This Claude Code skill teaches packet analysis and manipulation using Scapy, a Python library for crafting, sending, and dissecting network packets across protocol layers. Use it when investigating security incidents, analyzing pcap files for anomalies like SYN floods or DNS exfiltration, extracting protocol fields, implementing network scans, or building threat detection rules that require granular packet-level inspection.

View source Repository: Anthropic-Cybersecurity-Skills

Install in Claude Code

Copy

git clone --depth 1 https://github.com/mukul975/Anthropic-Cybersecurity-Skills /tmp/analyzing-network-packets-with-scapy && cp -r /tmp/analyzing-network-packets-with-scapy/skills/analyzing-network-packets-with-scapy ~/.claude/skills/analyzing-network-packets-with-scapy

Then start a new Claude Code session; the skill loads automatically.

Definition

SKILL.md

# Analyzing Network Packets with Scapy

## Overview

Scapy is a Python packet manipulation library that enables crafting, sending, sniffing, and dissecting network packets at granular protocol layers. This skill covers using Scapy for security-relevant tasks including TCP/UDP/ICMP packet crafting, pcap file analysis, protocol field extraction, SYN scan implementation, DNS query analysis, and detecting anomalous traffic patterns such as unusually fragmented packets or malformed headers.

## When to Use

- When investigating security incidents that require analyzing network packets with scapy
- 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

- Python 3.8+ with `scapy` library installed (`pip install scapy`)
- Root/administrator privileges for raw socket operations (sniffing, sending)
- Npcap (Windows) or libpcap (Linux) for packet capture
- Authorization to perform packet operations on target network

## Steps

1. Read and parse pcap/pcapng files with `rdpcap()` for offline analysis
2. Extract protocol layers (IP, TCP, UDP, DNS, HTTP) and field values
3. Compute traffic statistics: top talkers, protocol distribution, port frequency
4. Detect SYN flood patterns by analyzing TCP flag ratios
5. Identify DNS exfiltration indicators via query length and entropy analysis
6. Craft custom probe packets for authorized network testing
7. Export findings as structured JSON report

## Expected Output

JSON report containing packet statistics, protocol distribution, top source/destination IPs, detected anomalies (SYN floods, DNS tunneling indicators, fragmentation attacks), and per-flow summaries.