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Wireshark Basics & Packet Analysis

Shubham
Shubham
Cybersecurity Enthusiast

What is Wireshark​

okay let me go through it straight forward

wireshark is a free and open-source packet analyzer used to capture and inspect network traffic. you can either sniff live packets or load pcap files for analysis.

lame language definition:
wireshark is basically a microscope for network traffic — you can zoom into every packet and see all details

formal definition:
wireshark is a cross-platform network protocol analyzer that captures, decodes, and displays packets across OSI layers, enabling low-level inspection, filtering, and traffic analysis.

Why Wireshark Matters​

  • troubleshoot network issues
  • inspect protocol behavior (dns, http, tcp, udp, tls, etc.)
  • analyze suspicious or malicious traffic
  • understand real packet structures
  • extract files or data from captures
  • essential tool for both networking and cybersecurity

lame language definition:
if you want to see exactly what your computer is “saying”, wireshark is the tool

formal definition:
wireshark provides detailed packet-level visibility for diagnostics, protocol research, security auditing, and digital forensics.

Basic Wireshark Interface​

when you open a capture, you mainly work with:

  • packet list pane → shows all packets
  • packet details pane → shows protocol breakdown for selected packet
  • packet bytes pane → raw hex/ASCII data
  • display filter bar → to narrow down what you want to see

you can load .pcap or .pcapng files or capture live traffic.

Packet Dissection​

every packet is shown layer by layer:

  • ethernet (source/dest MAC)
  • ip header (source/dest IP, TTL, protocol)
  • tcp/udp (ports, flags, seq numbers)
  • application data (http, dns, ftp, tls, etc.)

the details pane lets you drill down into any header field.

example things you might inspect:

  • TTL value
  • source/destination ports
  • HTTP host or user-agent
  • DNS query name
  • TCP handshake flags
  • payload bytes

Filtering Packets​

wireshark supports two kinds of filters:

capture filters​

applied before capturing, restrict what gets recorded.
example: only capture traffic on port 80 → tcp port 80

display filters​

applied to shown packets after loading a capture.
these are more powerful and commonly used.

examples:
dns
http
tcp.flags.syn == 1
ip.addr == 192.168.1.10
udp.port == 53

you can also right-click any field → “Apply as Filter” to generate syntax automatically.

Searching Inside Packets​

you can search for:

  • strings inside packet bytes
  • hostnames
  • ip addresses
  • http headers
  • filenames
  • hidden text in payload

useful for CTFs and malware pcaps.

Statistics Tools​

wireshark provides high-level summaries:

protocol hierarchy​

breakdown of all protocols in the capture → useful for spotting dominant traffic

endpoints​

shows all communicating IPs, MACs, ports

conversations​

shows who talked to whom and how much data was exchanged

capture file properties​

metadata about the pcap, sometimes includes hidden notes or flags

these tools let you get insights without reading every packet manually.

Common Use Cases​

identifying suspicious traffic​

filter by http, dns, unknown ports, large payloads, repeated requests, etc.

extracting files​

some http/ftp/unencrypted streams let you reconstruct transmitted files.

analyzing tcp handshakes​

useful for diagnosing connectivity issues.

spotting DNS exfiltration​

check unusually long TXT records or frequent DNS queries.

reading HTTP requests​

see urls, methods, cookies, headers (if unencrypted).

following a TCP stream​

reconstruct entire conversations (http pages, ftp sessions, etc.)

Conclusion​

wireshark is one of the most important tools for anyone learning networking or cybersecurity.
it shows you real traffic, real protocols, and real packet structures — no abstractions.

if you understand how to filter, dissect, and interpret packets in wireshark,
you basically understand how data truly moves across networks.

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