How to Capture udp Packets in Python

Capturing UDP (User Datagram Protocol) packets is a fundamental skill for network programmers and security enthusiasts. Python, being a versatile and powerful programming language, offers various libraries and tools to facilitate packet capture. In this article, we’ll explore how to capture UDP packets using Python, specifically focusing on the popular library Scapy.

What are UDP Packets?

UDP, or User Datagram Protocol, is one of the core protocols of the Internet Protocol (IP) suite. It operates at the transport layer and provides a connectionless, lightweight, and fast communication method for data transfer between devices on a network. Unlike TCP (Transmission Control Protocol), which is connection-oriented and ensures reliable data delivery, UDP is connectionless and does not guarantee delivery or order of packets.

How to Capture UDP Packets in Python?

Below, are the step-by-step Implementation of How to Capture UDP Packets in Python.

Create a Virtual Environment

First, create the virtual environment using the below commands

python -m venv env 
.\env\Scripts\activate.ps1

File Structure

Capture UDP Packets in Python

udp_response.py: In this example, This Python code creates a UDP server using the `socket` module. It specifies an IP address (127.0.0.1) and port (5005) to listen on, then creates a UDP socket. The server continuously listens for incoming UDP packets, printing details such as the sender’s address and the received data in UTF-8 encoding. The `while True` loop ensures the server remains active and responsive to incoming UDP packets.

Python3

import socket

# Define the UDP IP address and port to listen on
UDP_IP = "127.0.0.1"
UDP_PORT = 5005

# Create a UDP socket
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind((UDP_IP, UDP_PORT))

print(f"Listening for UDP packets on {UDP_IP}:{UDP_PORT}")

while True:
    # Receive data from the socket
    data, addr = sock.recvfrom(1024)
    print(f"Received packet from {addr}: {data.decode('utf-8')}")

packet.py: In this example, below code This Python script functions as a UDP client, sending the message “Hello, UDP!” to a specified target IP address and port (127.0.0.1:5005). It utilizes the `socket` module to create a UDP socket, sends the encoded message, and prints a confirmation. The `finally` block ensures proper socket closure.

Python3

import socket

UDP_IP = "127.0.0.1"  # Replace with the target IP address
UDP_PORT = 5005       # Replace with the target port

message = "Hello, UDP!"  # send the message via socket

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

try:
    sock.sendto(message.encode(), (UDP_IP, UDP_PORT))
    print(f"Sent UDP packet to {UDP_IP}:{UDP_PORT}: {message}")
finally:
    sock.close()

Run the Server

use the below command for run the server.

python script_name.py

Output

Sending and Receiving packets via socket

Video Demonstration

Advantages of UDP Packets in Python

• Low Latency: UDP minimizes communication delays by eliminating connection setup overhead.
• Simplicity: Lightweight and straightforward, UDP omits complex features for faster data transmission.
• Broadcast/Multicast Support: UDP enables efficient one-to-many communication for applications like live streaming.
• Connectionless Nature: No continuous connection maintenance simplifies data transfer in real-time scenarios.
• Real-Time Application Suitability: Ideal for time-sensitive applications like online gaming or VoIP, prioritizing data flow over perfect delivery