Uncomplicated Firewall & Network Configuration (UFW)

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Executive Summary

This project demonstrates secure network configuration and firewall management on a Linux host using UFW (Uncomplicated Firewall).
It showcases foundational firewall concepts—default policies, rule creation, IPv4/IPv6 management, ICMP behavior, logging, and troubleshooting—mirroring real-world junior sysadmin and security operations responsibilities.

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Table of Contents

• Project Overview
• Why This Project Matters
• Technologies Used
• Objectives
• Key Achievements
• Skills Demonstrated
• Firewall Configuration Walkthrough
  • Step 1: Verify Firewall Status
  • Step 2: Configure Default Policies
  • Step 3: Allow Specific Services
  • Step 4: Verify Connectivity
  • Step 5: Enable Firewall Logging
  • Step 6: Verify Final Configuration
  • Step 7: Manage Rules Dynamically
• Key Takeaways
• Recommendations for Future Enhancements

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Project Overview

This project demonstrates how to configure and manage the UFW firewall on Linux to enforce secure inbound and outbound traffic policies.

The configuration steps reflect core system administration tasks:

• Setting default deny/allow rules
• Opening only necessary services
• Managing IPv4 and IPv6 rule sets
• Implementing logging for visibility
• Validating rule behavior through testing

These steps build foundational knowledge for secure Linux system hardening.

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Why This Project Matters

• Reinforces secure system configuration principles
• Demonstrates least-privilege network access
• Highlights differences between IPv4 and IPv6 firewall behavior
• Shows practical firewall rule creation, deletion, and testing
• Builds confidence in using UFW for real-world system security

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Technologies Used

• Linux (Ubuntu-based systems)
• UFW (Uncomplicated Firewall)
• Bash
• IPv4 & IPv6
• ICMP / ping testing

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Objectives

• Configure UFW to enforce secure network boundaries
• Set and verify default inbound/outbound policies
• Enable and evaluate firewall logging
• Manage service-specific rules (HTTP, HTTPS, SSH)
• Understand IPv4 vs. IPv6 rule creation
• Troubleshoot connectivity using ICMP tools

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Key Achievements

• Configured secure default firewall posture
  Set “deny incoming” and “allow outgoing” baseline.

• Enabled and validated service-specific rules
  Opened ports 22, 80, 443 without unnecessary duplicates.

• Managed duplicate rules efficiently
  Demonstrated removal of redundant or conflicting entries.

• Enabled and reviewed UFW logging
  Captured allow/deny activity to support troubleshooting.

• Differentiated IPv4 and IPv6 rule behavior
  Ensured complete coverage across both protocols.

• Performed successful connectivity and rule validation tests
  Verified enforcement using ICMP ping and UFW status reports.

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Skills Demonstrated

• Linux System Administration
• Firewall Configuration & Hardening
• Traffic Filtering (IPv4 & IPv6)
• Rule Creation, Deletion, and Management
• Logging and Visibility Enhancements
• Troubleshooting Network Connectivity

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Firewall Configuration Walkthrough

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Step 1: Verify Firewall Status

sudo ufw status

Example Output:

Status: active
To                         Action      From
22/tcp                     ALLOW       Anywhere
Anywhere                   DENY        192.168.1.100
22/tcp (v6)                ALLOW       Anywhere (v6)

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Step 2: Configure Default Policies

sudo ufw default deny incoming
sudo ufw default allow outgoing

Creates a secure baseline: inbound traffic blocked unless explicitly allowed.

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Step 3: Allow Specific Services

sudo ufw allow http
sudo ufw allow https
sudo ufw allow 80
sudo ufw allow 443

Note: Running both allow http and allow 80 creates duplicate rules.
Use deletion to clean up:

sudo ufw delete allow 80

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Step 4: Verify Connectivity

ping -c 4 8.8.8.8

Confirms outbound traffic is allowed.

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Step 5: Enable Firewall Logging

sudo ufw logging on

Logs stored at:

/var/log/ufw.log

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Step 6: Verify Final Configuration

sudo ufw status verbose

Checks:

• Default inbound/outbound policies
• IPv4 & IPv6 rules
• Logging level
• Any deny/allow rules in effect

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Step 7: Manage Rules Dynamically

sudo ufw allow <port/service>
sudo ufw deny <port/service>
sudo ufw delete allow <port/service>

Examples:

sudo ufw deny 23/tcp
sudo ufw delete allow http

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Key Takeaways

• UFW provides a simple yet powerful firewall interface
• Default deny/allow rules create a strong security baseline
• Duplicate rules can occur (service vs port syntax) and should be managed intentionally
• IPv4 and IPv6 rules are created separately and must be handled as such
• Logging provides visibility into allow/deny decisions
• Connectivity testing is essential for validating configuration changes

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Recommendations for Future Enhancements

• Implement rate limiting for SSH (e.g., ufw limit ssh)
• Add application profiles under /etc/ufw/applications.d/
• Explore nftables as next-level firewall configuration
• Add monitoring using tools like Fail2Ban
• Test UFW rule conflicts and ordering behavior

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