ufw

install :
sudo apt install ufw

check status :
sudo ufw status verbose

enable ufw :
sudo ufw enable

disable ufw :
sudo ufw disable

allow :
sudo ufw allow 8080/tcp

allow range :
sudo ufw allow 9000:9100/tcp

allow spesific address :
sudo ufw allow from 192.168.1.234
sudo ufw allow from 192.168.1.234 to any port 8888

deny :
sudo ufw deny from 192.168.1.0/24
sudo ufw deny from 192.168.1.0/24 to any port 80

delete by port :
sudo ufw delete allow 8080

delete by numberd :
sudo ufw status numbered
sudo ufw delete 3 (hapus nomor yang diinginkan)