Networks

A comprehensive collection of laboratory exercises and theoretical materials for computer networks study.

Laboratory Overview

Exercise	Folder	Description
EP0	Laboratory/EP0/	Network packet analysis and PCAP file examination
EP1	Laboratory/EP1/	MQTT server implementation and performance testing
EP2	Laboratory/EP2/	Secure client-server game with encryption
EP3	Laboratory/EP3/	Firewall implementation and network switching
EP4	Laboratory/EP4/	Advanced networking concepts

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EP0 - Network Analysis

Location: Laboratory/EP0/

This exercise focuses on network packet analysis using PCAP files. It includes:

• pergunta.pcapng - Primary packet capture file for analysis
• ep0-arthur_font_gouveia/ - Solutions and detailed responses
  • pergunta2.pcapng - Additional packet capture file
  • respostas.txt - Answers and analysis results

Topics Covered:

• Packet capture and analysis
• Network traffic examination
• Protocol identification

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EP1 - MQTT Server

Location: Laboratory/EP1/

Implementation of an MQTT server with performance analysis. Includes:

• bash.sh - Utility bash scripts
• ep1-arthur_font_gouveia/ - Solution implementation
  • ep1-mqtt-server.c - MQTT server implementation
  • desempenho.c - Performance testing module
  • Makefile - Build configuration
  • README.md - Detailed exercise documentation
• Prints/ - Test output and results

Topics Covered:

• MQTT protocol implementation
• Server socket programming
• Performance benchmarking
• C networking fundamentals

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EP2 - Secure Game Server

Location: Laboratory/EP2/

A complete client-server game implementation with encryption and security. Includes:

• main.py - Main entry point
• client/ - Client-side code
  • client.py - Client implementation
  • game.py - Game logic
• server/ - Server-side code
  • server.py - Server implementation
  • connection.py - Connection management
  • user.py - User management
  • reboot.py - Server restart utilities
  • data/ - Data storage
• perm/ - Cryptographic keys
  • sk.pem - Private key
  • pk.pem - Public key
• scripts/ - Testing and automation
  • match.sh - Game match runner
  • player1, player2 - Player scripts

Topics Covered:

• Client-server architecture
• Encryption and SSL/TLS
• Public key cryptography
• Python socket programming
• Game protocol design

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EP3 - Firewall and Switch

Location: Laboratory/EP3/

Network firewall and switch implementation with configuration rules. Includes:

• firewall.py - Firewall implementation
• switch.py - Network switch implementation
• rules.json - Firewall rules configuration
• mac0352-relatorio-ep3.tex - LaTeX report document
• ep3-arthur_font_gouveia/ - Solution directory with README.md

Topics Covered:

• Firewall rule processing
• Network packet filtering
• Layer 2 switching
• Network security policies
• Rule configuration and management

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EP4 - Network Vulnerability Exploitation and Analysis

Location: Laboratory/EP4/

This exercise focuses on exploring and understanding real-world network security vulnerabilities. The objective is to identify a programming flaw that leads to a vulnerability, demonstrate and explain its exploitation and patch.

Vulnerability Studied: CVE-2020-8794

• Type: Out-of-bounds buffer read in DNS protocol parsing
• Affected Component: DNS response message handling
• Root Cause: Improper boundary checking when parsing three-digit DNS response codes without optional space and text
• Attack Vector: Malicious DNS server (client-side) or malicious DNS client (server-side)
• Impact: Buffer overflow leading to information disclosure or potential code execution

Files:

• Arthur_Lucas_EP4.pdf - Complete study and analysis report
• EP4.txt - Exercise description and requirements
• Roteiro.pdf - Presentation overview
• Supporting images:
  • codigo.png - Vulnerable code snippet
  • patch.png - Patched/fixed code
  • envelope.png - DNS message envelope structure
  • env malicioso.png - Malicious envelope construction

Topics Covered:

• Network security vulnerabilities (CVE analysis)
• DNS protocol exploitation techniques
• Buffer overflow vulnerabilities
• Out-of-bounds memory access
• Vulnerability remediation and secure patching
• Root cause analysis of programming flaws

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Related Repositories

• EP2 Repository: https://github.com/Agfont/Networks-EP2