[Linux] Set Up a Firewall with UFW on Ubuntu 16.04

Install

$ sudo apt-get install ufw

Check Status

$ sudo ufw status verbose
# Status: inactive
# Status: active / with the rules

Normal Flow

1 . allow all ports incoming and reject all ports outgoing

$ sudo ufw default deny incoming
$ sudo ufw default allow outgoing

2 . allow normal ports

$ sudo ufw allow ssh
$ sudo ufw allow http
$ sudo ufw allow https

3 . allow special ports (Optional)

$ sudo ufw allow 8080

4 . enable ufw firewall

$ sudo ufw enable

Other Instruction (Optional)

1 . allow ports section

$ sudo ufw allow 6000:6007/tcp
$ sudo ufw allow 6000:6007/udp

2 . allow ip

$ sudo ufw allow from 15.15.15.51
$ sudo ufw allow from 15.15.15.51 to any port 22

3 . allow subnet

$ sudo ufw allow from 15.15.15.0/24
$ sudo ufw allow from 15.15.15.0/24 to any port 22

4 . allow eth

$ sudo ufw allow in on eth0 to any port 80
$ sudo ufw allow in on eth1 to any port 3306

use $ ip addr to check eths

5 . deny

sudo ufw deny http
sudo ufw deny from 15.15.15.51

6 . delete rule

$ sudo ufw delete [Num]

use sudo ufw status numbered to check rule Num

7 . enable / disable / restart service

$ sudo ufw enable
$ sudo ufw disable
$ sudo ufw reset

reference

1. https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-14-04