Captures and analyzes network packet data using Wireshark and tshark to identify malicious traffic patterns, diagnose protocol issues, extract artifacts, and support incident response investigations on authorized network segments.

Analyzing Network Traffic with Wireshark When to Use Investigating suspected network intrusions by examining packet level evidence of command and control traffic, data exfiltration, or lateral movement Diagnosing network performance issues such as retransmissions, fragmentation, or DNS resolution failures Analyzing malware communication patterns by capturing traffic from sandboxed or isolated hosts Validating firewall and IDS rules by confirming what traffic is actually traversing network segments Extracting files, credentials, or indicators of compromise from captured network sessions Do not use to capture traffic on networks without authorization, to intercept private communications without legal authority, or as a substitute for full featured SIEM platforms in production monitoring. Prerequisites Wireshark 4.0+ and tshark command line utility installed Root/sudo privileges or membership in the wireshark group for live packet capture Network interface access (physical NIC, span port, or network tap) to the monitored segment Sufficient disk space for packet capture files (estimate 1 GB per minute on busy gigabit links) Familiarity with TCP/IP protocols, HTTP, DNS, TLS, and SMB at the packet level Workflow Step 1: Configure Capture Environment Set up the capture interface and filters to target relevant traffic: For Wireshark GUI, set capture filter in the Capture Options dialog before starting. Step 2: Apply Display Filters for Targeted Analysis Step 3: Protocol Specific Deep Analysis Step 4: Extract Artifacts and IOCs Step 5: Statistical Analysis and Anomaly Detection Step 6: Generate Reports and Export Evidence Key Concepts Term Definition Capture Filter (BPF) Berkeley Packet Filter syntax applied at capture time to limit which packets are recorded, reducing file size and improving performance Display Filter Wireshark specific filter syntax applied to already captured packets for focused analysis without altering the capture file PCAPNG Next generation packet capture format supporting multiple interfaces, name resolution, annotations, and metadata in a single file TCP Stream Reassembled sequence of TCP segments representing a complete bidirectional conversation between two endpoints Protocol Dissector Wireshark module that decodes a specific protocol's fields and structure, enabling deep inspection of packet contents IO Graph Time series visualization of packet or byte rates over the capture duration, useful for identifying traffic spikes or beaconing Tools & Systems Wireshark 4.0+ : GUI based packet analyzer with protocol dissectors for 3,000+ protocols, stream reassembly, and export capabilities tshark : Command line version of Wireshark for headless capture, batch processing, and scripted analysis pipelines tcpdump : Lightweight packet capture tool for quick captures on remote systems without GUI dependencies mergecap : Wireshark utility for combining multiple capture files into a single PCAP for unified analysis editcap : Wireshark utility for splitting, filtering, and converting between capture file formats Common Scenarios Scenario: Investigating Suspected Data Exfiltration via DNS Tunneling Context : The SOC team detected unusually high DNS query volumes from a workstation (10.10.3.45) to an external domain. The SIEM alert flagged DNS queries averaging 200 per minute compared to the baseline of 15. A packet capture was initiated from the network tap on the workstation's VLAN. Approach : 1. Capture traffic from the workstation's subnet using tshark i eth2 f "host 10.10.3.45 and port 53" w dns exfil investigation.pcapng 2. Analyze DNS query patterns: tshark r dns exfil investigation.pcapng Y "dns.qry.name contains \"suspect domain.xyz\"" T fields e frame.time e dns.qry.name 3. Examine subdomain labels for encoded data (long base64 like subdomains indicate tunneling): tshark r dns exfil investigation.pcapng Y "dns.qry.type == 16" T fields e dns.qry.name e dns.txt 4. Calculate data volume by summing query name lengths to estimate exfiltration bandwidth 5. Extract unique query names and decode base64 subdomains to recover exfiltrated content 6. Export evidence packets to a separate PCAP and generate SHA 256 hash for chain of custody Pitfalls : Capturing unfiltered traffic on a busy network and running out of disk space before collecting relevant data Using display filters instead of capture filters, resulting in massive files that are slow to process Overlooking encrypted DNS (DoH/DoT) traffic that bypasses traditional DNS capture on port 53 Failing to establish packet capture hash and chain of custody documentation for forensic evidence Output Format

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