Network Forensics — Reading Captures Like a Detective

Manish Garg
Manish Garg Associate of (ISC)² · RingSafe
Apr 27, 2026
11 min read
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Last updated: May 1, 2026

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Network forensics is the art of reconstructing what happened from packets and flow logs after the fact. This module is the practitioner walk-through: chain of custody, the evidence stack (PCAP + Zeek + flow + endpoint), the workflow for a compromise investigation, the most useful Wireshark + tshark + Zeek + RITA techniques, and the legal posture for evidence to hold up in Indian courts under the IT Act and DPDP context.

When an incident happens, the network is usually the only place where the full story is recorded — the endpoint can be wiped, logs can be tampered with, but packets-on-disk reflect what actually moved across the wire. Network forensics is the discipline of reconstructing the incident from that evidence. This module is the working introduction; pair with Module 2 (Wireshark fundamentals) and Module 15 (telemetry).

The forensic mindset — what we are actually trying to prove

Forensics is not just “look at the packets” — it is “answer specific questions defensibly”. Typical questions: when did the attacker first arrive? What did they reach? What did they take? How did they get in? Did they create persistence? Each question is addressed with a different lens: time-correlation across PCAP, flow logs, Zeek logs, and endpoint telemetry.

The forensic principleevery answer must be reproducible from the same evidence and resilient to challenge — by the attacker if there is later litigation, by the auditor when reviewing the post-incident report, by counsel preparing for regulatory notification. Sloppy provenance kills cases; “we think it happened around then” is not a finding. Always cite specific evidence (PCAP file + frame number, log file + timestamp + line) for every conclusion.

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