Introduction

UFW is a frontend tool for the iptables Linux firewall that makes it easy to implement custom local firewall rules. It is important to note that UFW is typically disabled by default.

Usage

Enable UFW:
ufw enable

Disable ufw:
ufw disable

List UFW rules:
ufw status verbose

List UFW rules (numbered):
ufw status numbered

List available UFW profiles:
ufw app list

Set default policies (deny inbound, allow outbound — the usual baseline):
ufw default deny incoming
ufw default allow outgoing

Enable logging:
ufw logging on

Reset all rules (start clean):
ufw --force reset

Practical Examples

Allow SSH access from internal network (ex: 172.16.0.0/24):
ufw allow from 172.16.0.0/24 to any port 22

Allow port 25565 access from anywhere:
ufw allow 25565

Find and delete a UFW rule:
ufw status numbered
ufw delete 3

Rate-limit SSH (denies an IP with 6+ connections in 30s — basic brute-force defense):
ufw limit 22/tcp

Deny a specific port:
ufw deny 23

Insert a rule at a specific position (rules are evaluated top-down, first match wins):
ufw insert 1 allow from 172.16.0.0/24

References

• https://www.digitalocean.com/community/tutorials/ufw-essentials-common-firewall-rules-and-commands
• https://help.ubuntu.com/community/UFW