Detailed Packet Analysis Using Wireshark – Capture, Filters, and Protocol Breakdown
Packet analysis is one of the most important skills in networking and cybersecurity. This post provides a deep, step-by-step explanation of packet analysis using Wireshark, based on the visual diagram shown above.
Wireshark is widely used by:
- Network Engineers
- SOC Analysts
- Incident Responders
- Penetration Testers
- Cybersecurity Students
Understanding packet analysis allows professionals to see exactly what is happening on a network instead of guessing.
What Is Packet Analysis?
Packet analysis is the process of capturing, inspecting, and analyzing network packets to understand communication between devices.
Each packet contains:
- Source and destination addresses
- Protocol information
- Flags and control data
- Payload (actual data)
Wireshark allows analysts to view packets at every layer of the OSI model.
What Is Wireshark?
Wireshark is an open-source network protocol analyzer that captures packets in real time and displays them in a human-readable format.
Wireshark works by placing the network interface into promiscuous mode, allowing it to capture all traffic passing through the interface.
1. Packet Capture (Sniffing)
Definition
Packet capture is the process of collecting raw network packets as they travel across a network.
How Packet Capture Works
- The network interface is set to promiscuous mode
- Wireshark listens to all incoming and outgoing traffic
- Packets are captured in real time
Wireshark uses capture engines such as libpcap or Npcap to collect packets.
Why Packet Capture Is Important
- Troubleshoot network issues
- Detect suspicious activity
- Analyze malware communication
- Understand protocol behavior
2. Filters in Wireshark (Focus on What Matters)
Modern networks generate a huge amount of traffic. Filters allow analysts to focus only on relevant packets.
Types of Filters
| Filter Type | Purpose | When Used |
|---|---|---|
| Capture Filter | Limits what is captured | Before capture |
| Display Filter | Filters displayed packets | After capture |
Capture Filters
Capture filters reduce storage and processing by capturing only specific traffic. They use BPF (Berkeley Packet Filter) syntax.
Examples:
host 192.168.1.1 port 53 tcp
Use capture filters when you know exactly what traffic you want to analyze.
Display Filters
Display filters allow you to search and analyze already captured traffic. They are more powerful and flexible than capture filters.
Examples:
http tcp.port == 80 tcp.flags.syn == 1 ip.addr == 192.168.1.10
Display filters are heavily used by SOC analysts and incident responders.
3. Protocol Breakdown (Deep Inspection)
Wireshark allows packet inspection at every layer of the OSI model. Each captured packet can be expanded to reveal detailed protocol information.
Packet List Pane
Displays a summary of each packet:
- Time
- Source
- Destination
- Protocol
- Length
- Info
Packet Details Pane (Protocol Hierarchy)
This section shows how the packet is structured layer by layer:
- Physical Layer – Frame length
- Data Link Layer – MAC addresses
- Network Layer – IP addresses
- Transport Layer – TCP/UDP ports and flags
- Application Layer – HTTP, DNS, FTP data
This view helps analysts understand encapsulation and protocol behavior.
Packet Bytes Pane (Hex & ASCII)
This pane displays the raw packet data in:
- Hexadecimal format
- ASCII representation
It is useful for:
- Malware analysis
- Exploit detection
- Payload inspection
Real-World Use Cases of Wireshark
- Detecting suspicious network traffic
- Investigating data exfiltration
- Analyzing DNS, HTTP, and HTTPS traffic
- Troubleshooting slow networks
- Learning how protocols really work
Why Packet Analysis Is Critical for Cybersecurity
| Benefit | Explanation |
|---|---|
| Visibility | See actual network activity |
| Threat Detection | Identify malicious behavior |
| Troubleshooting | Find root causes |
Interview-Ready Explanation
Wireshark is a packet analysis tool that captures and inspects network traffic, allowing analysts to filter packets and analyze protocol behavior across OSI layers.
Final Summary
Packet analysis using Wireshark is a foundational skill for networking and cybersecurity. Mastering capture techniques, filters, and protocol breakdown enables professionals to understand networks at a deep technical level.
If you can analyze packets confidently, you can troubleshoot and defend real networks 🔐
