performing-network-packet-capture-analysis

name	performing-network-packet-capture-analysis
description	Perform forensic analysis of network packet captures (PCAP/PCAPNG) using Wireshark, tshark, and tcpdump to reconstruct network communications, extract transferred files, identify malicious traffic, and establish evidence of data exfiltration or command-and-control activity. Use when performing forensic analysis of network packet captures (pcap/pcapng) using wireshark,.
domain	cybersecurity
subdomain	digital-forensics
tags	["pcap","wireshark","tshark","tcpdump","network-forensics","packet-capture","protocol-analysis","traffic-analysis","pcapng","network-evidence"]
version	1.0
author	oyi77
license	Apache-2.0
nist_csf	["RS.AN-01","RS.AN-03","DE.AE-02","RS.MA-01"]

Performing Network Packet Capture Analysis

Overview

Network packet captures (PCAP/PCAPNG files) represent the ultimate source of truth about network activity and provide irrefutable evidence of communications between hosts. PCAP files log every packet transmitted over a network segment, making them vital for forensic investigations involving data exfiltration, command-and-control communications, lateral movement, malware delivery, and unauthorized access. Wireshark is the primary tool for interactive analysis, while tshark provides command-line capabilities for automated processing and scripting. Modern PCAPNG format supports additional metadata including interface descriptions, capture comments, precise timestamps, and per-packet annotations.

When to Use

Trigger phrases:

• "performing network packet capture analysis"

• "Perform forensic analysis of network packet captures (PCAP/PCAPNG) using Wiresha"

• When conducting security assessments that involve performing network packet capture analysis

• When following incident response procedures for related security events

• When performing scheduled security testing or auditing activities

• When validating security controls through hands-on testing

Prerequisites

• Wireshark 4.x with protocol dissectors
• tshark command-line tool (included with Wireshark)
• tcpdump for capture and basic filtering
• Python 3.8+ with scapy and pyshark libraries
• Sufficient disk space for PCAP files (can be multi-GB)

Capture Techniques

This section covers capture techniques for performing network packet capture analysis.

• Ensure all prerequisites are met before proceeding
• Follow the documented workflow steps in sequence
• Record results and any anomalies encountered during this phase

tcpdump

# Capture all traffic on interface eth0
tcpdump -i eth0 -w capture.pcap

# Capture with rotation (100MB files, keep 10)
tcpdump -i eth0 -w capture_%Y%m%d_%H%M%S.pcap -C 100 -W 10

# Capture specific host traffic
tcpdump -i eth0 host 192.168.1.100 -w host_traffic.pcap

# Capture specific port traffic
tcpdump -i eth0 port 443 -w https_traffic.pcap

# Capture with BPF filter for suspicious ports
tcpdump -i eth0 'port 4444 or port 8080 or port 1337' -w suspicious.pcap