Firewalls Concepts

DigitalOcean Cloud Firewalls are a network-based, stateful firewall service for Droplets provided at no additional cost. Cloud firewalls block all traffic that isn’t expressly permitted by a rule.

Learn how to organize infrastructure involving cloud firewalls, like splitting rules across firewalls by role and using tags.
This community tutorial covers how firewalls work, with a focus on stateful software firewalls (like iptables and FirewallD) as they relate to cloud servers
Using a firewall is as much about making intelligent policy decisions as it is about learning the syntax. This community tutorial covers decisions you must make when implementing a firewall. These choices affect how your firewall behaves, how locked down your server is, and how it will respond to various common situations. This tutorial uses iptables as an example, but the decisions are relevant regardless of the tools used.