ufw

Enable ufw

$ sudo ufw enable

$ sudo ufw disable

$ sudo ufw status numbered

$ sudo ufw allow 5432 comment "Service"

$ sudo ufw allow proto tcp from 192.168.0.4 to any port 22

$ sudo ufw deny 80

$ sudo ufw deny proto udp from any to any port 8412:8500

$ sudo ufw delete rule_number

ufw [--dry-run] command [rule]

ufw (Uncomplicated Firewall) is a frontend for iptables designed to make firewall configuration easier. It provides a user-friendly interface for managing netfilter firewall rules while supporting both simple and complex rule specifications.

enable

Enable the firewall and load rules on boot

Disable the firewall and unload rules

Reload the firewall configuration

Reset to installation defaults

Show firewall status and rules

Show detailed status with logging and default policies

Show rules with line numbers for deletion

Show changes without applying them

Execute without confirmation prompts

/etc/ufw/ufw.conf

Main configuration file controlling enable/disable state, logging level, and IPv6 support.

Custom iptables rules applied before ufw-managed rules.

Custom iptables rules applied after ufw-managed rules.

Default policy settings and input/output/forward policy configuration.

allow

Permit matching traffic

Block matching traffic silently

Block matching traffic and notify sender

Rate-limit connections (blocks after 6+ attempts in 30 seconds)

Remove a rule by specification or number

Add rule at specified position

Add rule before all others of same IP type

Simple: ufw allow 22/tcp
With comment: ufw allow 80 comment 'HTTP'
Port range: ufw allow 6000:6007/tcp
Multiple ports: ufw allow 80,443/tcp
From address: ufw allow from 192.168.1.0/24
Full syntax: ufw allow proto tcp from any to any port 80

logging off

Disable logging

Enable logging (low level)

Set logging verbosity level

Default policies are deny incoming, allow outgoing, deny forwarding. Enabling ufw may disrupt existing connections if rules are not configured first. Use --dry-run to preview changes before applying.

ufw was developed by Canonical for Ubuntu to simplify iptables firewall management. It was first released in Ubuntu 8.04 (2008) and has become a popular firewall tool across many Linux distributions.

iptables(8), ip6tables(8), ufw-framework(8)