How to Learn Packet Sniffing for CEH Certification?

Introduction

Packet sniffing is one of the most powerful and frequently tested modules in CEH theory and practical exams. Real attackers use sniffing to steal credentials, session cookies, credit card numbers, and internal traffic. As an ethical hacker, you must know how to perform and detect these attacks.

In CEH v13, sniffing covers passive capture, active MITM, ARP/DNS poisoning, SSL stripping, and prevention techniques.

Passive vs Active Sniffing: Know the Difference

• Passive Sniffing: Capture packets without sending anything (works only on hub or Wi-Fi)
• Active Sniffing: Perform ARP/DNS poisoning to become man-in-the-middle

CEH exam focuses 80% on active sniffing techniques.

Start with simple capture before moving to attacks.

Essential Tools for Packet Sniffing in CEH

Wireshark Mastery: Filters & Analysis Commands You Must Know

• ip.addr == 192.168.1.10
• tcp.port == 80 or http
• http contains "password"
• tcp.flags.syn == 1
• Follow → TCP Stream
• Statistics → Conversations

Practice these filters daily.

ARP Poisoning Attack Step-by-Step (Bettercap Method)

• bettercap -iface eth0
• net.probe on
• net.show
• set arp.spoof.targets 192.168.1.100
• arp.spoof on
• http.proxy on (for SSL stripping)

SSL Stripping & Credential Harvesting

• Downgrade HTTPS to HTTP
• Capture login forms in clear text
• Use Bettercap http.proxy + sslstrip module
• Export captured data as PCAP

SSL stripping still works on poorly configured sites.

DNS Spoofing Attack

• Create fake response with Bettercap dns.spoof
• Redirect login.company.com to your IP
• Host fake login page
• Capture credentials

Sniffing on Switched Networks

• ARP poisoning bypasses switch MAC learning
• Port mirroring (SPAN) in real environments
• Hub usage in labs (rare today)

Prevention Techniques You Must Know for Exam

• Static ARP entries
• Port security on switches
• Dynamic ARP inspection (DAI)
• HTTPS with HSTS
• VPN and encrypted tunnels

Always test prevention in your lab.

Best Labs to Practice Packet Sniffing Legally

• TryHackMe – Network Fundamentals & Sniffing rooms
• Hack The Box – Legacy, Blue, Lame machines
• VulnHub – Kioptrix series
• PortSwigger MITM labs
• Build own lab: Kali + Windows + Router VM

Conclusion: Your Packet Sniffing Mastery Plan

Follow this exact 15-day roadmap:

• Days 1–5 → Wireshark filters & normal capture
• Days 6–10 → ARP poisoning + credential harvesting
• Days 11–15 → SSL stripping + DNS spoofing + prevention

Once you can steal credentials from your own lab in under 10 minutes, you are 100% ready for CEH theory and practical sniffing questions.

Enroll in a CEH course that includes live sniffing labs and real traffic scenarios.

Frequently Asked Questions

Is packet sniffing tested in CEH Practical?

Yes, usually 2–3 flags involve MITM or credential capture.

Which tool replaced Ettercap in modern CEH?

Bettercap – faster and more reliable.

Can I sniff on Wi-Fi networks?

Yes, using monitor mode and a compatible adapter.

Is SSL stripping still possible in 2025?

Yes, on sites without HSTS preload.

Do I need a special network card?

Only for Wi-Fi monitor mode; not needed for LAN labs.

Is passive sniffing undetectable?

Almost always – no packets are sent.

How to detect ARP poisoning?

Tools like arpwatch or XArp.

Can I use Wireshark on Windows?

Yes, with Npcap driver.

Is tcpdump better than Wireshark?

For scripting and servers, yes. For analysis, Wireshark wins.

Will VPN stop sniffing?

Yes, encrypted tunnel prevents MITM.

How many questions on sniffing in theory?

Usually 8–12 questions.

Is Bettercap included in Kali?

Yes, pre-installed in latest versions.

Can I sniff HTTPS traffic?

Only if you install your CA certificate (advanced).

Best resource for Wireshark filters?

Official Wireshark Wiki + PortSwigger labs.

How to start today?

Download Kali → Open Wireshark → Start capturing on your home network.