Open port on Oracle Cloud

The Ubuntu firewall is disabled by default. However, you still need to update your iptables configuration to allow HTTP traffic. Update iptables with the following commands.

sudo iptables -I INPUT 6 -m state --state NEW -p tcp --dport 80 -j ACCEPT
sudo netfilter-persistent save

The commands add a rule to allow HTTP traffic and saves the changes to the iptables configuration files.