Basic usage of UFW on Ubuntu

Ubuntu comes packaged with a very easy to use firewall tool called UFW. This is literally meaning uncomplicated firewall for Ubuntu.

The UFW syntax is short and sweet option compared to iptables.

Turn on and enable UFW with (UFW is disabled by default):

sudo ufw enable

Turn off UFW with:

sudo ufw disable

Check UFW status and current rules with:

sudo ufw status

Allowing and denying

The format for setting a firewall rule is

sudo ufw allow|deny port/protocol

With protocol being optional.

Allowing incoming UDP on port 81:

sudo ufw allow 81/udp

Allow incoming TCP and UDP on port 81:

sudo ufw allow 81

Denying TCP on port 400:

sudo ufw deny 400/tcp

Allowing from an ip:

sudo ufw allow from 111.222.3.44

Blocking connections from an ip:

sudo ufw deny from 111.22.333.4

Allow HTTP or HTTPS:

sudo ufw allow http
sudo ufw allow https

Allow SSH:

sudo ufw allow ssh

Deny or allow by service name:

sudo ufw deny servicename