Raspberry Pi Forums

I found my solution here
http://bbs.archbang.org/viewtopic.php?pid=31848#p31848

To start ufw on boot, create a shell script containing 2 lines

Sudo nano start_ufw.sh

#!/bin/sh
/usr/sbin/ufw enable

Ctrl-X to save it

sudo cp start_ufw.sh /etc/rc.local

To check:

sudo reboot

sudo ufw status

The proposed solution it's not ideal.

Accordingly to this post
The right solutions should be to edit this file
and add the following line at the end of the first section The result should be like this:

[Unit]
Description=Uncomplicated firewall
Documentation=man:ufw(8)
DefaultDependencies=no
Before=network.target
After=netfilter-persistent.service

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/lib/ufw/ufw-init start quiet
ExecStop=/lib/ufw/ufw-init stop

[Install]
WantedBy=multi-user.target

Adding this line we tell the operating system to load ufw after the netfilter-persistent.
After this all should be fine.

Bye