// Aula 11 - Trabalhando com o Firewall UFW

http://wiki.ubuntu-br.org/UFW

# sudo apt install ufw

# sudo systemctl enable --now ufw

# sudo ufw allow 22/tcp

# sudo ufw enable

# sudo ufw status verbose

# iptables -L

# iptables -L -n | grep 22

# ip6tables -L -n | grep 22

# sudo ufw allow 53

sudo ufw status verbose

# cd /etc/ufw

# ls -l

# vim /etc/ufw/before.rules 

# Mangle table added by Donnie
*mangle
:PREROUTING ACCEPT [0:0]
-A PREROUTING -m conntrack --ctstate INVALID -j DROP
-A PREROUTING -p tcp -m tcp ! --tcp-flags FIN,SYN,RST,ACK SYN -m conntrack --ctstate NEW -j DROP
COMMIT

# vim /etc/ufw/before6.rules

# sudo ufw reload

# iptables -L
# iptables -t mangle -L
# ip6tables -L
# ip6tables -t mangle -L

# ufw status