[Ubuntu] Setup firewall using UFW

UFW is a default firewall. it is more easier than iptables. But iptables supports more various options and functions for building high-quality service.

1. Set UFW Enable/Disable

#> ufw enable

#> ufw disable

2. Check UFW status

#> ufw status verbose

3. Check default rule

#> ufw show raw

4. Allow/Deny default rule

#> ufw default allow

#> ufw default deny

5. Allow/Deny specific port and protocol

#> ufw allow [port]

#> ufw allow [port]/tcp

#> ufw allow [port]/udp

#> ufw deny[port]

#> ufw deny[port]/tcp

#> ufw deny[port]/udp