安裝防火牆 ufw , Debian 8 ( Jessie )

在 Terminal (終端機) 依次執行以下指令 :
su
apt-get install ufw
ufw default deny incoming
ufw default allow outgoing
ufw enable
(  ufw status verbose  可顯示目前 ufw 狀態   )
(  ufw disable 關閉防火牆  )
exit


參考文章 :
https://wiki.debian.org/Uncomplicated%20Firewall%20%28ufw%29
https://www.linode.com/docs/security/firewalls/configure-firewall-with-ufw
https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-14-04
http://www.arthurtoday.com/2013/12/ubuntu-ufw-add-firewall-rules.html