Managing Ports on Ubuntu and Debian-based Systems

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This guide provides concise steps to manage ports on Ubuntu and other Debian-based systems. Ports control network traffic and security. Below are methods to allow or block ports using tools compatible with most Debian derivatives.

Prerequisites

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• A Debian-based operating system (e.g., Ubuntu, Linux Mint, Debian).
• Sudo or root privileges to execute commands.

Methods to Allow or Block Ports

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1. Using UFW (Uncomplicated Firewall)

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UFW is the default, user-friendly firewall management tool on Ubuntu and works seamlessly on most Debian-based systems.

Steps:

Check if UFW is Installed and Active:

sudo apt update
sudo apt install ufw

Enable UFW:

sudo ufw enable

Allow a Port (e.g., 80):

sudo ufw allow 80

Block a Port (e.g., 22):

sudo ufw deny 22

Allow a Port with a Specific Protocol (e.g., 443 with TCP):

sudo ufw allow 443/tcp

Check Active Rules:

sudo ufw status

Remove a Rule (e.g., remove port 80):

sudo ufw delete allow 80

2. Using iptables

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For advanced users, iptables provides fine-grained control over network traffic. It is compatible with Ubuntu and other Debian-based systems.

Steps:

Allow a Port (e.g., 8080):

sudo iptables -A INPUT -p tcp --dport 8080 -j ACCEPT

Block a Port (e.g., 3306):

sudo iptables -A INPUT -p tcp --dport 3306 -j DROP

Delete a Rule (e.g., unblock port 8080):

sudo iptables -D INPUT -p tcp --dport 8080 -j ACCEPT

Save Changes to Persist Rules Across Reboots:

sudo apt install iptables-persistent
sudo netfilter-persistent save

3. Using FirewallD

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FirewallD is a dynamic firewall management tool compatible with most modern Linux distributions, including Ubuntu and Debian derivatives.

Steps:

Install and Enable FirewallD:

sudo apt update
sudo apt install firewalld
sudo systemctl start firewalld
sudo systemctl enable firewalld

Allow a Port (e.g., 22):

sudo firewall-cmd --permanent --add-port=22/tcp
sudo firewall-cmd --reload

Block a Port (e.g., 8080):

sudo firewall-cmd --permanent --remove-port=8080/tcp
sudo firewall-cmd --reload

List Current Rules:

sudo firewall-cmd --list-all

Summary

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• UFW: Simplified configuration; ideal for most users.
• Iptables: Advanced configurations; for experienced users.
• FirewallD: Dynamic and robust; suited for evolving setups.

This guide applies to Ubuntu, Debian, and other Debian-based operating systems