=Uncomplicated Firewall
manera alternativa de montar reglas de acceso con una sintáxis más sencilla, monta tablas y cadenas a su antojo

== sintaxis y argumentos
<code bash>ufw [--dry-run] [options] [rule syntax]</code>
  * options:
    * allow
    * deny
    * reject
    * limit: bloquea el acceso después de 6 intentos de conexión en 30 segundos (sospechas)
    * status: displays if the firewall is active or inactive
    * show: displays the current running rules on your firewall
    * reset: disables and resets the firewall to default
    * reload: reloads the current running firewall
    * disable: disables the firewall

== uso por defecto
  * consultar:<code bash>grep 'DEFAULT_' /etc/default/ufw</code>
  * cambiar:<code bash>sudo ufw default deny incoming
sudo ufw default allow outgoing</code>

== uso
  * estado:<code bash>
sudo ufw status verbose
sudo ufw status numbered
</code>
  * reportes:<code bash>
sudo ufw show added
sudo ufw show raw
sudo ufw show listening
sudo ufw show builtins
sudo ufw show before-rules
sudo ufw show user-rules
sudo ufw show after-rules
sudo ufw show logging-rules
</code>
  * gestionar servicio/protocolo:<code bash>
sudo ufw allow 22
sudo ufw deny 22
sudo ufw deny 22/tcp
sudo ufw allow ssh # /etc/services</code>
  * bloquear una ip+puerto a una ip específica:<code bash>sudo ufw deny from 192.168.2.100/8 to 192.168.2.101 port 25</code>
  * rango de puertos:<code bash>sudo ufw allow 6000:7000 proto tcp</code>
  * bloquear tráfico entrante, permitir saliente a un puerto:<code bash>sudo ufw allow out on eth0 to any port 25 proto tcp
sudo ufw deny in on eth0 from any 25 proto tcp</code>
  * eliminar una regla:<code bash>sudo ufw status numbered
sudo ufw delete NUM # según lista</code>
  * insertar una regla en una posición concreta:<code bash>sudo ufw insert 1 allow from 10.213.6.0/24 port ssh</code>


/via: [[https://www.linux.com/learn/introduction-uncomplicated-firewall-ufw]]
/via: [[https://www.cyberciti.biz/faq/howto-configure-setup-firewall-with-ufw-on-ubuntu-linux/]]
/via: [[https://www.digitalocean.com/community/tutorials/como-configurar-un-firewall-con-ufw-en-ubuntu-18-04-es]]

== ficheros
  * **/etc/default/ufw**: high level configuration, such as default policies, IPv6 support and kernel modules to use
    * ''sudo sed -i s/IPV6=yes/IPV6=no/g /etc/default/ufw''
  * **/etc/ufw/before[6].rules**: rules in these files are evaluated before any rules added via the ufw command
  * /**etc/ufw/after[6].rules**: rules in these files are evaluated after any rules added via the ufw command
  * **/etc/ufw/sysctl.conf**: kernel network tunables
  * **/var/lib/ufw/user[6].rules** or **/lib/ufw/user[6].rules** (0.28 and later): rules added via the ufw command (should not normally be edited by hand)
  * **/etc/ufw/ufw.conf**: sets whether or not ufw is enabled on boot, and in 9.04 (ufw 0.27) and later, sets the LOGLEVEL
  * **/etc/ufw/after.init**: initialization customization script run after ufw is initialized (ufw 0.34 and later)
  * **/etc/ufw/before.init**: initialization customization script run before ufw is initialized (ufw 0.34 and later)


== sites
  * [[https://www.digitalocean.com/community/tutorials/how-to-setup-a-firewall-with-ufw-on-an-ubuntu-and-debian-cloud-server]]
  * [[https://wiki.ubuntu.com/UncomplicatedFirewall]]


== ejemplos
  * permitir acceso a un puerto desde un rango IP:<code bash># ufw allow from 192.168.1.0/24 to 192.168.1.50 port ssh</code>
    * a partir de la regla de arriba (y tener el resto de puertos cerrados) ha salido este mensaje en ''/var/log/syslog'':<code>Nov  8 17:28:44 macnux kernel: [10687.134802] [UFW BLOCK] IN=eth0 OUT= MAC=01:00:5e:00:00:01:f8:8e:85:40:78:be:08:00 SRC=192.168.1.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=0 DF PROTO=2</code>
    * mirando por internet, se trata de multicast:
      * [[https://ubuntuforums.org/showthread.php?t=2195355]]
      * [[https://en.wikipedia.org/wiki/Multicast_address]]
    * y de ahí he llegado a averiguar el rango de IPs que tiene facebook asignados: [[http://ipinfo.io/AS32934]]