performing-network-traffic-analysis-with-zeek

name	performing-network-traffic-analysis-with-zeek
description	Deploy Zeek network security monitor to capture, parse, and analyze network traffic metadata for threat detection, anomaly identification, and forensic investigation. Use when deploying zeek network security monitor to capture, parse, and analyze.
domain	cybersecurity
subdomain	network-security
tags	["zeek","network-monitoring","traffic-analysis","ids","nids","pcap","threat-detection","forensics","siem-integration"]
version	1.0
author	oyi77
license	Apache-2.0
nist_csf	["PR.IR-01","DE.CM-01","ID.AM-03","PR.DS-02"]

Performing Network Traffic Analysis with Zeek

Overview

Zeek (formerly Bro) is an open-source network analysis framework that operates as a passive network security monitor. Unlike traditional signature-based IDS tools, Zeek generates high-fidelity structured logs from observed network traffic, capturing detailed metadata for protocols including HTTP, DNS, TLS, SSH, SMTP, FTP, and dozens more. Zeek's extensible scripting language enables custom detection logic, behavioral analysis, and automated response. This skill covers deploying Zeek, understanding its log architecture, writing custom detection scripts, and integrating outputs with SIEM platforms.

When to Use

Trigger phrases:

• "performing network traffic analysis with zeek"

• "Deploy Zeek network security monitor to capture, parse, and analyze network traf"

• When conducting security assessments that involve performing network traffic analysis with zeek

• 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

• Linux server (Ubuntu 22.04+ or CentOS 8+) with 4+ CPU cores and 8GB+ RAM
• Network TAP or SPAN port mirroring configured for traffic capture
• Zeek 6.0+ installed (via package manager or source compilation)
• Root or capture group privileges for packet capture
• SIEM platform (Splunk, ELK Stack, or QRadar) for log ingestion

Core Concepts

This section covers core concepts for performing network traffic analysis with zeek.

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

Zeek Architecture

Zeek operates in two main modes:

1. Live Capture - Monitors traffic in real-time on one or more network interfaces
2. Offline Analysis - Processes saved PCAP files for retrospective analysis

The processing pipeline consists of:

• Packet Capture Layer - Reads raw packets from interfaces or PCAP files
• Event Engine - Reassembles TCP streams and generates protocol events
• Script Interpreter - Executes Zeek scripts that process events and generate logs
• - Writes structured logs in TSV, JSON, or custom formats