Linux: How to Open, Close, and Manage Ports with UFW Firewall

Understanding UFW (Uncomplicated Firewall)

• 💡 UFW stands for Uncomplicated Firewall, a command-line tool for managing firewall rules on Linux systems.
• 🔑 Administrative permissions are required to use UFW commands, necessitating the use of sudo.

Enabling and Checking Firewall Status

• ⚙️ To activate the firewall, use the command sudo ufw enable. The firewall will also be enabled on system startup.
• 📊 You can verify the firewall's status by running sudo ufw status. Initially, it might show as inactive by default.

Managing Network Ports with UFW

• 🚪 To open a specific port, use sudo ufw allow followed by the port number (e.g., sudo ufw allow 22 for SSH).
• 🌐 You can also specify the protocol when allowing ports, such as sudo ufw allow 80/tcp for HTTP.
• 🚫 To block or deny a port, use sudo ufw deny followed by the port number (e.g., sudo ufw deny 443 for HTTPS).

Advanced UFW Rule Management

• 🔢 To view all configured rules with their corresponding numbers, use sudo ufw status numbered.
• 🗑️ Rules can be deleted by their number (e.g., sudo ufw delete [rule_number]) or by specifying the exact rule (e.g., sudo ufw delete deny 443).

Disabling the Firewall

• 🛑 If you need to disable the firewall, use the command sudo ufw disable. This will stop the firewall and disable it on system startup.