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