Firewall Management - UFW

UFW stands for Uncomplicated Firewall.

It is an interface to manage the Netfilter firewall on Linux, which is the system’s packet filtering system. UFW was developed to simplify the process of configuring firewall rules through the iptables utility.

UFW is the most popular and recommended method to manage the firewall on Debian- and Ubuntu-based distributions.

UFW Command Examples (Practical Guide)

Most UFW commands require superuser privileges (sudo).

1. Status Check

Check if UFW is active and view the current rules:

Action	Command	Example Output
Check Status	ufw status	Status: inactive (or active)
Check Details	ufw status verbose	Lists all rules in detail.

2. Enabling and Disabling

It’s crucial to set the rules before enabling to avoid locking yourself out of the server.

Action	Command	Note
Enable UFW	ufw enable	Warning: If you don’t have an allow ssh rule, you’ll lose remote access.
Disable UFW	ufw disable	Turns off the firewall (not recommended).
Reset Rules	ufw reset	Removes all user-defined rules.

3. Default Policies

Configure what happens to traffic that does not match any specific rule.

Action	Command	Result
Deny Incoming (Recommended)	ufw default deny incoming	No external connections are allowed unless explicitly specified.
Allow Outgoing	ufw default allow outgoing	Your server can initiate connections to the outside world.

4. Adding Rules (Allowing)

Goal	Command	Note
Allow SSH (Port 22)	ufw allow ssh	Uses the service name to open port 22/TCP.
Allow HTTP (Port 80)	ufw allow http	Opens port 80/TCP.
Allow HTTPS (Port 443)	ufw allow 443/tcp	Opens by port number and protocol.
Specific Port	ufw allow 5432/udp	Opens port 5432 only for the UDP protocol.
Specific IP Traffic	ufw allow from 192.168.1.100 to any port 3306	Allows only the IP 192.168.1.100 to access port 3306 (MySQL).

5. Removing Rules

Removal can be done by rule number or by rule text.

Action	Command	Note
Remove by Text	ufw delete allow http	Removes the rule allowing http (80/TCP).
Remove by Number	ufw status numbered ufw status delete [número]	The first command returns a list with existing rules and their positions, the second removes the rule at the selected position.