Scapy Made Simple: Learn Packet Crafting and Sniffing in Python

 Scapy

Scapy is a powerful Python-based interactive packet manipulation tool and library used for:

• Packet crafting
• Sniffing
• Decoding
• Sending and receiving network packets

It’s widely used in cybersecurity, penetration testing, network diagnostics, and research due to its flexibility and ease of use.

What Can Scapy Do?

Here’s a breakdown of Scapy’s capabilities:

1. Packet Crafting

You can create custom packets from scratch or modify existing ones. For example:

This sends an ICMP (ping) packet to Google’s DNS server.

2. Packet Sniffing

Scapy can capture packets from a network interface:

This captures 10 packets and prints a summary.

3. Protocol Support

• Scapy supports a wide range of protocols:
• Ethernet
• IP, TCP, UDP, ICMP
• ARP, DNS, DHCP
• HTTP, TLS (limited)
• Custom protocols (you can define your own)

4. Network Discovery

You can perform tasks like:

• ARP scanning
• Traceroute
• DNS queries
• Port scanning

Example of ARP scan:

5. Packet Analysis

Scapy can dissect and analyze packets:

This displays all fields and layers of the captured packet.

6. Automation & Scripting

Because it’s Python-based, you can automate complex tasks and integrate with other Python libraries.

How Scapy Works

Scapy builds packets layer by layer. Each layer is a Python object. For example:

This creates an Ethernet frame that contains an IP packet and a TCP segment, targeting port 80.

You can inspect or modify any field:

Installation

To install Scapy:

 

For full functionality (like GUI or advanced sniffing), you may need additional tools like tcpdump, Wireshark, or libpcap.

Use Cases

• Penetration Testing: Crafting malicious packets, testing firewall rules.
• Network Troubleshooting: Diagnosing connectivity issues.
• Security Research: Protocol analysis, fuzzing.
• Education: Learning how protocols work.