ufw

The Uncomplicated Firewall (ufw) is a user-friendly interface for managing netfilter, the standard firewall utility included with most Ubuntu and Debian-based Linux distributions. ufw simplifies firewall configuration by providing straightforward commands for enabling, disabling, and managing firewall rules without requiring extensive networking knowledge.

To enable ufw to start automatically at boot:

systemctl enable ufw

To start or stop the firewall:

ufw enable
ufw disable

To see the status, run

ufw status
ufw status numbered

Open Ports

Here are some commands to open ports.

ufw allow ssh
ufw allow http
ufw allow https
ufw allow 3333/tcp

Following command open tcp ports 8000 to 9000.

ufw allow 8000:9000/tcp

Disable all other ports by default for incoming and allow all outbound traffic

ufw default deny incoming
ufw default allow outgoing

Block a port, below example will block port 80

ufw deny 80/tcp

Whitelist an IP

To allow an IP to access all services

ufw allow from IP_ADDR_HERE

To allow to specific PORT

ufw allow from IP_ADDR_HERE proto tcp to any port PORT_HERE
ufw allow from IP_ADDR_HERE proto udp to any port PORT_HERE

Enable Logging

To enable logging, run

ufw logging on

By default ufw logs to /var/log/kern.log.

To log to different file, edit

vi /etc/rsyslog.d/20-ufw.conf

Uncomment the line

:msg,contains,"[UFW " /var/log/ufw.log

rstart rsyslog

systemctl restart rsyslog

To allow all Cloudflare IP addresses for web traffic, use the following command. This is useful if your server is behind Cloudflare’s CDN:

for cfip in `curl -sw '\n' https://www.cloudflare.com/ips-v{4,6}`; do ufw allow proto tcp from $cfip comment 'Cloudflare IP'; done

To list available apps, run

ufw app list

See firewall