IPTables

Allow All Incoming HTTP

• sudo iptables -A INPUT -p tcp --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
• sudo iptables -A OUTPUT -p tcp --sport 80 -m conntrack --ctstate ESTABLISHED -j ACCEPT

link: https://www.digitalocean.com/community/tutorials/iptables-essentials-common-firewall-rules-and-commands